Copilot commented on code in PR #12743:
URL: https://github.com/apache/trafficserver/pull/12743#discussion_r2640694146


##########
example/cripts/cache_groups.cc:
##########
@@ -0,0 +1,106 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#define CRIPTS_CONVENIENCE_APIS 1
+
+#include <cripts/CacheGroup.hpp>
+#include <cripts/Preamble.hpp>
+
+do_create_instance()
+{
+  // Create a cache-group for this site / remap rule(s). They can be shared.
+  instance.data[0] = cripts::Cache::Group::Manager::Factory("example");
+}
+
+do_delete_instance()
+{
+  void *ptr = AsPointer(instance.data[0]);
+
+  if (ptr) {
+    delete static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+    instance.data[0] = nullptr;
+  }
+}
+
+do_cache_lookup()
+{
+  if (cached.response.lookupstatus != cripts::LookupStatus::MISS) {
+    void *ptr = AsPointer(instance.data[0]);
+
+    if (ptr) {
+      auto date = cached.response.AsDate("Date");
+
+      if (date > 0) {

Review Comment:
   The comparison operator should use '!=' instead of '>' for comparing with 
time_point zero to check validity. Time points don't have a natural ordering 
relative to "zero" in the same way integers do, and using '>' is semantically 
unclear. Consider using '!=' to check if the date is valid/not-zero.
   ```suggestion
         if (date != 0) {
   ```



##########
include/cripts/CacheGroup.hpp:
##########
@@ -0,0 +1,216 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+#pragma once
+
+#include <unordered_map>
+#include <string>
+#include <vector>
+#include <chrono>
+#include <mutex>
+#include <shared_mutex>
+#include <fstream>
+#include <atomic>
+#include <memory>
+#include <cstdint>
+
+#include "cripts/Context.hpp"
+#include "cripts/Time.hpp"
+
+// Implemented in the .cc file
+int _cripts_cache_group_sync(TSCont cont, TSEvent event, void *edata);
+
+namespace cripts::Cache
+{
+
+class Group
+{
+private:
+  using self_type = Group;
+
+  struct _Entry {
+    cripts::Time::Point timestamp; // Timestamp of when the entry was created
+    size_t              length;    // Length of the group ID
+    uint32_t            prefix;    // First 4 characters of the group ID
+    uint64_t            hash;      // Hash value of the group ID, needed when 
writing to disk
+  };
+
+  // Header structure for on-disk map files (after VERSION field)
+  struct _MapHeader {
+    time_t created_ts;
+    time_t last_write_ts;
+    time_t last_sync_ts;
+    size_t count;
+  };
+
+  using _MapType = std::unordered_map<uint64_t, _Entry>;
+
+  struct _MapSlot {
+    std::unique_ptr<_MapType> map;
+    std::string               path;
+    cripts::Time::Point       created;
+    cripts::Time::Point       last_write;
+    cripts::Time::Point       last_sync;
+  };
+
+public:
+  static constexpr uint64_t VERSION = (static_cast<uint64_t>('C') << 56) | 
(static_cast<uint64_t>('G') << 48) |
+                                      (static_cast<uint64_t>('M') << 40) | 
(static_cast<uint64_t>('A') << 32) |
+                                      (static_cast<uint64_t>('P') << 24) | 
(static_cast<uint64_t>('S') << 16) |
+                                      (static_cast<uint64_t>('0') << 8) | 
0x00; // Change this on version bump
+
+  static constexpr std::chrono::seconds DEFAULT_MAX_AGE{63072000}; // 2 Years, 
max cache lifetime in ATS as well
+
+  Group(const std::string &name, const std::string &base_dir, size_t 
max_entries = 1024, size_t num_maps = 3)
+  {
+    Initialize(name, base_dir, num_maps, max_entries, DEFAULT_MAX_AGE);
+  }
+
+  // Not used at the moment.
+  Group() = default;
+
+  ~Group() { WriteToDisk(); }
+
+  Group(const self_type &)                = delete;
+  self_type &operator=(const self_type &) = delete;
+
+  void Initialize(const std::string &name, const std::string &base_dir, size_t 
num_maps = 3, size_t max_entries = 1024,
+                  std::chrono::seconds max_age = DEFAULT_MAX_AGE);
+
+  void
+  SetMaxEntries(size_t max_entries)
+  {
+    std::unique_lock lock(_mutex);
+    _max_entries = max_entries;
+  }
+
+  void
+  SetMaxAge(std::chrono::seconds max_age)
+  {
+    std::unique_lock lock(_mutex);
+    _max_age = max_age;
+  }
+
+  void Insert(cripts::string_view key);
+  void Insert(const std::vector<cripts::string_view> &keys);
+  bool Lookup(cripts::string_view key, cripts::Time::Point age) const;
+  bool Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const;
+
+  bool
+  Lookup(cripts::string_view key, time_t age) const
+  {
+    return Lookup(key, cripts::Time::Clock::from_time_t(age));
+  }
+
+  bool
+  Lookup(const std::vector<cripts::string_view> &keys, time_t age) const
+  {
+    return Lookup(keys, cripts::Time::Clock::from_time_t(age));
+  }
+
+  cripts::Time::Point
+  LastSync() const
+  {
+    std::shared_lock lock(_mutex);
+    return _last_sync;
+  }
+
+  void WriteToDisk();
+  void LoadFromDisk();
+
+private:
+  mutable std::shared_mutex _mutex;
+  std::string               _name        = "CacheGroup";
+  size_t                    _num_maps    = 3;
+  size_t                    _max_entries = 1024;
+  std::chrono::seconds      _max_age     = DEFAULT_MAX_AGE;
+  std::atomic<size_t>       _map_index   = 0;

Review Comment:
   The _map_index member is declared as std::atomic but is accessed without 
atomic operations in multiple places. In the Insert method, it's read and 
written non-atomically (lines 126, 144), and in the Lookup method, it's read 
without atomic load (line 176). Since _mutex protects these operations, using 
std::atomic is unnecessary and misleading. Either use proper atomic operations 
or change it to a regular size_t since it's already protected by the mutex.
   ```suggestion
     size_t                    _map_index   = 0;
   ```



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);

Review Comment:
   The transaction log is opened with std::ios::app but never explicitly opened 
in binary mode. Since the log stores binary Entry structures, it should be 
opened with std::ios::binary to prevent text-mode transformations on some 
platforms. This could lead to data corruption on Windows or other systems that 
distinguish between text and binary modes.
   ```suggestion
       _txn_log.open(_log_path, std::ios::app | std::ios::out | 
std::ios::binary);
   ```



##########
include/cripts/CacheGroup.hpp:
##########
@@ -0,0 +1,216 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+#pragma once
+
+#include <unordered_map>
+#include <string>
+#include <vector>
+#include <chrono>
+#include <mutex>
+#include <shared_mutex>
+#include <fstream>
+#include <atomic>
+#include <memory>
+#include <cstdint>
+
+#include "cripts/Context.hpp"
+#include "cripts/Time.hpp"
+
+// Implemented in the .cc file
+int _cripts_cache_group_sync(TSCont cont, TSEvent event, void *edata);
+
+namespace cripts::Cache
+{
+
+class Group

Review Comment:
   Missing documentation for the Cache Groups feature. The code lacks 
explanation of key concepts like what cache groups are used for, how the 
rotation mechanism works, what the parameters mean (num_maps, max_entries, 
max_age), and how the disk persistence works. Consider adding comprehensive 
documentation including class-level and method-level comments explaining the 
design and usage patterns.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);
+
+  if (!o_file) {
+    TSWarning("cripts::Cache::Group: Failed to open temp file for sync: %s.", 
tmp_path.c_str());
+    return;
+  }
+
+  // Helper lambda to append data to the write buffer
+  auto _AppendToBuffer = [&](const void *data, size_t size) {
+    if (write_failed) {
+      return;
+    }
+    if (buf_pos + size > buffer.size()) {
+      o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+      if (!o_file) {
+        write_failed = true;
+        return;
+      }
+      buf_pos = 0;
+    }
+    std::memcpy(buffer.data() + buf_pos, static_cast<const std::byte *>(data), 
size);
+    buf_pos += size;
+  };
+
+  _MapHeader header{.created_ts    = 
cripts::Time::Clock::to_time_t(slot.created),
+                    .last_write_ts = 
cripts::Time::Clock::to_time_t(slot.last_write),
+                    .last_sync_ts  = 
cripts::Time::Clock::to_time_t(slot.last_sync),
+                    .count         = slot.map->size()};
+
+  _AppendToBuffer(&VERSION, sizeof(VERSION));
+  _AppendToBuffer(&header, sizeof(header));
+
+  // Write entries
+  for (const auto &[_, entry] : *slot.map) {
+    _AppendToBuffer(&entry, sizeof(entry));
+  }
+
+  if (buf_pos > 0 && !write_failed) {
+    o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+  }
+  o_file.flush();
+  o_file.close();
+
+  if (write_failed || !o_file) {
+    TSWarning("cripts::Cache::Group: Failed to write to temp file `%s'.", 
tmp_path.c_str());
+    std::filesystem::remove(tmp_path);
+    return;
+  }
+
+  if (std::rename(tmp_path.c_str(), slot.path.c_str()) != 0) {
+    TSWarning("cripts::Cache::Group: Failed to rename temp file `%s' to 
`%s'.", tmp_path.c_str(), slot.path.c_str());
+    std::filesystem::remove(tmp_path);
+  }

Review Comment:
   If std::rename fails, the temporary file is removed but the original file 
may be in an inconsistent state. The error handling should ensure that either 
the update succeeds completely or the original file remains intact. Consider 
implementing a more robust error recovery strategy, such as keeping a backup of 
the original file before attempting the rename.



##########
doc/developer-guide/cripts/cripts-misc.en.rst:
##########
@@ -414,3 +414,63 @@ Debug logging uses the same format string syntax as 
``fmt::format()`` in ``libfm
     debug tags in your ATS configuration to enable debug output for your 
Cripts.
     The default debug tag for Cripts is the name of the Cript itself, either
     the Cript source file, or the compiled plugin name.
+
+Cache Groups
+============
+
+As a way to manage association between cache entries, Cripts provides an 
infrastructure
+for cache groups. A cache group is a set of cache entries that are logically
+associated with each other via custom identifiers.
+
+Example implementation of the Cache Groups RFC
+
+.. code-block:: cpp
+
+   do_create_instance()
+   {
+     // Create a cache-group for this site / remap rule(s). They can be shared.
+     instance.data[0] = cripts::Cache::Group::Manager::Factory("example_site");
+   }
+
+   do_delete_instance()
+   {
+     void *ptr = AsPointer(instance.data[0]);
+
+     if (ptr) {
+       delete static_cast<std::shared_ptr<cripts::Cache::Group> *>(ptr);
+       instance.data[0] = nullptr;
+     }
+   }
+
+   do_cache_lookup()
+   {
+     if (cached.response.lookupstatus != cripts::LookupStatus::MISS) {
+       void *ptr = AsPointer(instance.data[0]);
+
+       if (ptr) {
+         auto date = cached.response.AsDate("Date");
+         if (date > 0) {
+           auto cache_groups = cached.response["Cache-Groups"];
+           if (!cache_groups.empty()) {
+             borrow cg = *static_cast<std::shared_ptr<cripts::Cache::Group> 
*>(ptr);

Review Comment:
   The same comparison pattern appears here. Using '>' to compare a time_t 
value with 0 works but using '!=' would be more semantically clear to indicate 
checking for validity rather than ordering.
   ```suggestion
            if (date != 0) {
              auto cache_groups = cached.response["Cache-Groups"];
              if (!cache_groups.empty()) {
                borrow cg = 
*static_cast<std::shared_ptr<std::shared_ptr<cripts::Cache::Group> *>(ptr);
   ```



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;

Review Comment:
   The hash collision detection at line 129 only checks prefix and length but 
doesn't verify the actual key content. While the prefix check provides some 
collision resistance, two different keys could have the same hash, same length, 
and same 4-byte prefix, leading to incorrect cache group behavior. Consider 
either storing the full key or adding a more robust collision detection 
mechanism.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;

Review Comment:
   The same hash collision issue exists in the Lookup method. The check at line 
189 verifies hash, timestamp, length, and prefix, but doesn't confirm the 
actual key matches. This could result in false positive lookups when hash 
collisions occur with keys that have matching length and prefix.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);
+
+  if (!o_file) {
+    TSWarning("cripts::Cache::Group: Failed to open temp file for sync: %s.", 
tmp_path.c_str());
+    return;
+  }
+
+  // Helper lambda to append data to the write buffer
+  auto _AppendToBuffer = [&](const void *data, size_t size) {

Review Comment:
   The lambda function name '_AppendToBuffer' uses PascalCase which is 
inconsistent with C++ naming conventions. Lambda names, if given, should follow 
the same conventions as regular functions (typically snake_case or camelCase in 
this codebase). Consider renaming to 'append_to_buffer' or 'appendToBuffer'.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);

Review Comment:
   The variable name 'o_file' is inconsistent with the naming style used 
elsewhere in the codebase. Other file streams use full names like 'file' or 
'log'. Consider renaming to 'tmp_file' or 'temp_file' for better consistency 
and clarity.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);
+
+  if (!o_file) {
+    TSWarning("cripts::Cache::Group: Failed to open temp file for sync: %s.", 
tmp_path.c_str());
+    return;
+  }
+
+  // Helper lambda to append data to the write buffer
+  auto _AppendToBuffer = [&](const void *data, size_t size) {
+    if (write_failed) {
+      return;
+    }
+    if (buf_pos + size > buffer.size()) {
+      o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+      if (!o_file) {
+        write_failed = true;
+        return;
+      }
+      buf_pos = 0;
+    }
+    std::memcpy(buffer.data() + buf_pos, static_cast<const std::byte *>(data), 
size);
+    buf_pos += size;
+  };
+
+  _MapHeader header{.created_ts    = 
cripts::Time::Clock::to_time_t(slot.created),
+                    .last_write_ts = 
cripts::Time::Clock::to_time_t(slot.last_write),
+                    .last_sync_ts  = 
cripts::Time::Clock::to_time_t(slot.last_sync),
+                    .count         = slot.map->size()};
+
+  _AppendToBuffer(&VERSION, sizeof(VERSION));
+  _AppendToBuffer(&header, sizeof(header));
+
+  // Write entries
+  for (const auto &[_, entry] : *slot.map) {
+    _AppendToBuffer(&entry, sizeof(entry));
+  }
+
+  if (buf_pos > 0 && !write_failed) {
+    o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+  }
+  o_file.flush();
+  o_file.close();
+
+  if (write_failed || !o_file) {
+    TSWarning("cripts::Cache::Group: Failed to write to temp file `%s'.", 
tmp_path.c_str());
+    std::filesystem::remove(tmp_path);
+    return;
+  }
+
+  if (std::rename(tmp_path.c_str(), slot.path.c_str()) != 0) {
+    TSWarning("cripts::Cache::Group: Failed to rename temp file `%s' to 
`%s'.", tmp_path.c_str(), slot.path.c_str());
+    std::filesystem::remove(tmp_path);
+  }
+}
+
+void
+Cache::Group::clearLog()
+{
+  std::error_code ec;
+
+  _txn_log.close();
+  std::filesystem::remove(_log_path, ec);
+  if (ec) {
+    TSWarning("cripts::Cache::Group: Failed to clear transaction log `%s': 
%s", _log_path.c_str(), ec.message().c_str());
+  }
+}
+
+// Singleton instance for the Cache::Group::Manager
+Cache::Group::Manager &
+Cache::Group::Manager::_instance()
+{
+  static Cache::Group::Manager inst;
+  return inst;
+}
+
+void *
+Cache::Group::Manager::Factory(const std::string &name, size_t max_entries, 
size_t num_maps)
+{
+  std::lock_guard lock(_instance()._mutex);
+  auto           &groups = _instance()._groups;
+
+  if (auto it = groups.find(name); it != groups.end()) {
+    if (auto group = it->second.lock()) {
+      return new std::shared_ptr<Group>(std::move(group));
+    }
+  }
+
+  if (!_instance()._base_dir.empty()) {
+    auto group = std::make_shared<Group>(name, _instance()._base_dir, 
max_entries, num_maps);
+
+    groups[name] = group;
+    return new std::shared_ptr<Group>(std::move(group));
+  } else {
+    TSError("cripts::Cache::Group: Failed to get runtime directory for 
initialization.");
+    return nullptr;
+  }
+}
+
+void
+Cache::Group::Manager::_scheduleCont()
+{
+  if (!_cont) {
+    _cont = TSContCreate(_cripts_cache_group_sync, TSMutexCreate());
+    TSContDataSet(_cont, this);
+  }
+
+  if (_action) {
+    TSActionCancel(_action); // Can this even happen ?

Review Comment:
   The comment states "Can this even happen ?" which indicates uncertainty 
about the logic. If TSActionCancel is called on a valid action and then 
scheduling a new one, this makes sense. However, the comment suggests the 
developer is unsure about this scenario. Either clarify the comment to explain 
when this can occur, or remove it if the logic is straightforward.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);
+
+  if (!o_file) {
+    TSWarning("cripts::Cache::Group: Failed to open temp file for sync: %s.", 
tmp_path.c_str());
+    return;
+  }
+
+  // Helper lambda to append data to the write buffer
+  auto _AppendToBuffer = [&](const void *data, size_t size) {
+    if (write_failed) {
+      return;
+    }
+    if (buf_pos + size > buffer.size()) {
+      o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+      if (!o_file) {
+        write_failed = true;
+        return;
+      }
+      buf_pos = 0;
+    }
+    std::memcpy(buffer.data() + buf_pos, static_cast<const std::byte *>(data), 
size);
+    buf_pos += size;
+  };
+
+  _MapHeader header{.created_ts    = 
cripts::Time::Clock::to_time_t(slot.created),
+                    .last_write_ts = 
cripts::Time::Clock::to_time_t(slot.last_write),
+                    .last_sync_ts  = 
cripts::Time::Clock::to_time_t(slot.last_sync),
+                    .count         = slot.map->size()};
+
+  _AppendToBuffer(&VERSION, sizeof(VERSION));
+  _AppendToBuffer(&header, sizeof(header));
+
+  // Write entries
+  for (const auto &[_, entry] : *slot.map) {
+    _AppendToBuffer(&entry, sizeof(entry));
+  }
+
+  if (buf_pos > 0 && !write_failed) {
+    o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+  }
+  o_file.flush();
+  o_file.close();
+
+  if (write_failed || !o_file) {
+    TSWarning("cripts::Cache::Group: Failed to write to temp file `%s'.", 
tmp_path.c_str());
+    std::filesystem::remove(tmp_path);
+    return;
+  }
+
+  if (std::rename(tmp_path.c_str(), slot.path.c_str()) != 0) {
+    TSWarning("cripts::Cache::Group: Failed to rename temp file `%s' to 
`%s'.", tmp_path.c_str(), slot.path.c_str());
+    std::filesystem::remove(tmp_path);
+  }
+}
+
+void
+Cache::Group::clearLog()
+{
+  std::error_code ec;
+
+  _txn_log.close();
+  std::filesystem::remove(_log_path, ec);
+  if (ec) {
+    TSWarning("cripts::Cache::Group: Failed to clear transaction log `%s': 
%s", _log_path.c_str(), ec.message().c_str());
+  }
+}
+
+// Singleton instance for the Cache::Group::Manager
+Cache::Group::Manager &
+Cache::Group::Manager::_instance()
+{
+  static Cache::Group::Manager inst;
+  return inst;
+}
+
+void *
+Cache::Group::Manager::Factory(const std::string &name, size_t max_entries, 
size_t num_maps)
+{
+  std::lock_guard lock(_instance()._mutex);
+  auto           &groups = _instance()._groups;
+
+  if (auto it = groups.find(name); it != groups.end()) {
+    if (auto group = it->second.lock()) {
+      return new std::shared_ptr<Group>(std::move(group));
+    }
+  }
+
+  if (!_instance()._base_dir.empty()) {
+    auto group = std::make_shared<Group>(name, _instance()._base_dir, 
max_entries, num_maps);
+
+    groups[name] = group;
+    return new std::shared_ptr<Group>(std::move(group));
+  } else {
+    TSError("cripts::Cache::Group: Failed to get runtime directory for 
initialization.");
+    return nullptr;
+  }
+}
+
+void
+Cache::Group::Manager::_scheduleCont()
+{
+  if (!_cont) {
+    _cont = TSContCreate(_cripts_cache_group_sync, TSMutexCreate());
+    TSContDataSet(_cont, this);
+  }
+
+  if (_action) {
+    TSActionCancel(_action); // Can this even happen ?
+    _action = nullptr;
+  }
+
+  _action = TSContScheduleEveryOnPool(_cont, _CONT_SYNC_INTERVAL * 1000, 
TS_THREAD_POOL_TASK);

Review Comment:
   The continuation is scheduled with TSContScheduleEveryOnPool but there's no 
check whether scheduling succeeded. If _action is nullptr after this call, the 
continuation won't run and cache groups won't be synced to disk, potentially 
leading to data loss. Add error checking and logging if scheduling fails.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination

Review Comment:
   The comment contains a typo: "contination" should be "continuation".



##########
include/cripts/CacheGroup.hpp:
##########
@@ -0,0 +1,216 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+#pragma once
+
+#include <unordered_map>
+#include <string>
+#include <vector>
+#include <chrono>
+#include <mutex>
+#include <shared_mutex>
+#include <fstream>
+#include <atomic>
+#include <memory>
+#include <cstdint>
+
+#include "cripts/Context.hpp"
+#include "cripts/Time.hpp"
+
+// Implemented in the .cc file
+int _cripts_cache_group_sync(TSCont cont, TSEvent event, void *edata);
+
+namespace cripts::Cache
+{
+
+class Group
+{
+private:
+  using self_type = Group;
+
+  struct _Entry {
+    cripts::Time::Point timestamp; // Timestamp of when the entry was created
+    size_t              length;    // Length of the group ID
+    uint32_t            prefix;    // First 4 characters of the group ID
+    uint64_t            hash;      // Hash value of the group ID, needed when 
writing to disk
+  };
+
+  // Header structure for on-disk map files (after VERSION field)
+  struct _MapHeader {
+    time_t created_ts;
+    time_t last_write_ts;
+    time_t last_sync_ts;
+    size_t count;
+  };
+
+  using _MapType = std::unordered_map<uint64_t, _Entry>;
+
+  struct _MapSlot {
+    std::unique_ptr<_MapType> map;
+    std::string               path;
+    cripts::Time::Point       created;
+    cripts::Time::Point       last_write;
+    cripts::Time::Point       last_sync;
+  };
+
+public:
+  static constexpr uint64_t VERSION = (static_cast<uint64_t>('C') << 56) | 
(static_cast<uint64_t>('G') << 48) |
+                                      (static_cast<uint64_t>('M') << 40) | 
(static_cast<uint64_t>('A') << 32) |
+                                      (static_cast<uint64_t>('P') << 24) | 
(static_cast<uint64_t>('S') << 16) |
+                                      (static_cast<uint64_t>('0') << 8) | 
0x00; // Change this on version bump
+
+  static constexpr std::chrono::seconds DEFAULT_MAX_AGE{63072000}; // 2 Years, 
max cache lifetime in ATS as well
+
+  Group(const std::string &name, const std::string &base_dir, size_t 
max_entries = 1024, size_t num_maps = 3)
+  {
+    Initialize(name, base_dir, num_maps, max_entries, DEFAULT_MAX_AGE);

Review Comment:
   The Initialize method is called from the constructor with parameters in a 
different order (num_maps and max_entries are swapped). The constructor at line 
78 passes max_entries as the third parameter and num_maps as the fourth, but 
Initialize expects num_maps third and max_entries fourth. This will cause the 
values to be assigned incorrectly, leading to unexpected behavior.



##########
src/cripts/CacheGroup.cc:
##########
@@ -0,0 +1,441 @@
+/*
+  Licensed to the Apache Software Foundation (ASF) under one
+  or more contributor license agreements.  See the NOTICE file
+  distributed with this work for additional information
+  regarding copyright ownership.  The ASF licenses this file
+  to you under the Apache License, Version 2.0 (the
+  "License"); you may not use this file except in compliance
+  with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+#include <algorithm>
+#include <filesystem>
+
+#include "ts/ts.h"
+#include "cripts/CacheGroup.hpp"
+
+inline static uint32_t
+_make_prefix_int(cripts::string_view key)
+{
+  uint32_t prefix = 0;
+
+  std::memcpy(&prefix, key.data(), std::min<size_t>(4, key.size()));
+  return prefix;
+}
+
+// Stuff around the disk sync contination
+constexpr auto _CONT_SYNC_INTERVAL = 10; // How often to run the continuation
+constexpr int  _SYNC_GROUP_EVERY   = 60; // Sync each group every 60s
+
+int
+_cripts_cache_group_sync(TSCont cont, TSEvent /* event */, void * /* edata */)
+{
+  auto           *mgr = static_cast<cripts::Cache::Group::Manager 
*>(TSContDataGet(cont));
+  std::lock_guard lock(mgr->_mutex);
+  auto           &groups = mgr->_groups;
+
+  const size_t max_to_process = (groups.size() + (_SYNC_GROUP_EVERY - 1)) / 
_SYNC_GROUP_EVERY;
+  size_t       processed      = 0;
+  auto         now            = cripts::Time::Clock::now();
+
+  for (auto it = groups.begin(); it != groups.end() && processed < 
max_to_process;) {
+    if (auto group = it->second.lock()) {
+      if (group->LastSync() + std::chrono::seconds{_SYNC_GROUP_EVERY} < now) {
+        group->WriteToDisk();
+        ++processed;
+      }
+      ++it;
+    } else {
+      // The group has been deleted, remove it from the map
+      it = groups.erase(it);
+    }
+  }
+
+  return TS_SUCCESS;
+}
+
+namespace cripts
+{
+
+void
+Cache::Group::Initialize(const std::string &name, const std::string &base_dir, 
size_t num_maps, size_t max_entries,
+                         std::chrono::seconds max_age)
+{
+  cripts::Time::Point zero = cripts::Time::Point{};
+  cripts::Time::Point now  = cripts::Time::Clock::now();
+
+  _name        = name;
+  _num_maps    = num_maps;
+  _max_entries = max_entries;
+  _max_age     = max_age;
+
+  _base_dir = base_dir + "/" + _name;
+  _log_path = _base_dir + "/" + "txn.log";
+
+  if (!std::filesystem::exists(_base_dir)) {
+    std::error_code ec;
+
+    std::filesystem::create_directories(_base_dir, ec);
+    if (ec) {
+      TSWarning("cripts::Cache::Group: Failed to create directory `%s': %s", 
_base_dir.c_str(), ec.message().c_str());
+    } else {
+      std::filesystem::permissions(_base_dir, 
std::filesystem::perms::group_write, std::filesystem::perm_options::add, ec);
+      if (ec) {
+        TSWarning("cripts::Cache::Group: Failed to set permissions on `%s': 
%s", _base_dir.c_str(), ec.message().c_str());
+      }
+    }
+  }
+
+  for (size_t ix = 0; ix < _num_maps; ++ix) {
+    _slots.emplace_back(_MapSlot{.map        = std::make_unique<_MapType>(),
+                                 .path       = _base_dir + "/map_" + 
std::to_string(ix) + ".bin",
+                                 .created    = zero,
+                                 .last_write = zero,
+                                 .last_sync  = zero});
+  }
+
+  _slots[0].created    = now;
+  _slots[0].last_write = now;
+
+  LoadFromDisk();
+  _last_sync = now;
+}
+
+void
+Cache::Group::Insert(cripts::string_view key)
+{
+  static const std::hash<cripts::string_view> hasher;
+
+  // Trim any "'s and white spaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  auto     now    = cripts::Time::Clock::now();
+  auto     hash   = static_cast<uint64_t>(hasher(key));
+  uint32_t prefix = _make_prefix_int(key);
+
+  std::unique_lock lock(_mutex);
+
+  auto &slot = _slots[_map_index];
+  auto  it   = slot.map->find(hash);
+
+  if (it != slot.map->end() && it->second.length == key.size() && 
it->second.prefix == prefix) {
+    it->second.timestamp = now;
+    slot.last_write      = now;
+    appendLog(it->second);
+
+    return;
+  }
+
+  Cache::Group::_Entry entry{.timestamp = now, .length = key.size(), .prefix = 
prefix, .hash = hash};
+
+  slot.map->insert_or_assign(hash, entry);
+  slot.last_write = now;
+  appendLog(entry);
+
+  if (slot.map->size() > _max_entries || (now - slot.created) > _max_age) {
+    _map_index = (_map_index + 1) % _slots.size();
+
+    auto &next_slot = _slots[_map_index];
+
+    if (next_slot.last_write > next_slot.last_sync) {
+      TSWarning("cripts::Cache::Group: Rotating unsynced map for `%s'! This 
may lead to data loss.", _name.c_str());
+    }
+    next_slot.map->clear();
+    next_slot.created    = now;
+    next_slot.last_write = now;
+    syncMap(_map_index); // Sync to disk will make sure it's empty on disk
+  }
+}
+
+void
+Cache::Group::Insert(const std::vector<cripts::string_view> &keys)
+{
+  for (auto &key : keys) {
+    Insert(key);
+  }
+}
+
+bool
+Cache::Group::Lookup(cripts::string_view key, cripts::Time::Point age) const
+{
+  // Trim any "'s and whitespaces from the key
+  key.trim_if(&isspace).trim('"');
+
+  uint64_t         hash = 
static_cast<uint64_t>(std::hash<cripts::string_view>{}(key));
+  std::shared_lock lock(_mutex);
+
+  for (size_t i = 0; i < _slots.size(); ++i) {
+    size_t      map_index = (_map_index + _slots.size() - i) % _slots.size();
+    const auto &slot      = _slots[map_index];
+
+    if (slot.last_write < age) {
+      continue; // Skip maps that haven't been written to since this time
+    }
+
+    const auto &map = *slot.map;
+    auto        it  = map.find(hash);
+
+    if (it != map.end()) {
+      const Cache::Group::_Entry &entry = it->second;
+
+      if (entry.timestamp < age || entry.length != key.size() || entry.prefix 
!= _make_prefix_int(key)) {
+        continue;
+      }
+
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool
+Cache::Group::Lookup(const std::vector<cripts::string_view> &keys, 
cripts::Time::Point age) const
+{
+  for (auto &key : keys) {
+    if (Lookup(key, age)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+void
+Cache::Group::LoadFromDisk()
+{
+  std::unique_lock lock(_mutex);
+  std::ifstream    log(_log_path, std::ios::binary);
+
+  for (size_t slot_ix = 0; slot_ix < _slots.size(); ++slot_ix) {
+    auto         &slot       = _slots[slot_ix];
+    uint64_t      version_id = 0;
+    _MapHeader    header{};
+    std::ifstream file(slot.path, std::ios::binary);
+
+    if (!file) {
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&version_id), sizeof(version_id));
+    if (version_id != VERSION) {
+      TSWarning("cripts::Cache::Group: Version mismatch for map file: %s, 
expected %llu, got %llu. Skipping this map.",
+                slot.path.c_str(), static_cast<unsigned long long>(VERSION), 
static_cast<unsigned long long>(version_id));
+      continue;
+    }
+
+    file.read(reinterpret_cast<char *>(&header), sizeof(header));
+    if (!file) {
+      TSWarning("cripts::Cache::Group: Failed to read header from map file: 
%s. Skipping this map.", slot.path.c_str());
+      continue;
+    }
+
+    slot.created    = cripts::Time::Clock::from_time_t(header.created_ts);
+    slot.last_write = cripts::Time::Clock::from_time_t(header.last_write_ts);
+    slot.last_sync  = cripts::Time::Clock::from_time_t(header.last_sync_ts);
+
+    for (size_t i = 0; i < header.count; ++i) {
+      Cache::Group::_Entry entry;
+
+      file.read(reinterpret_cast<char *>(&entry), sizeof(entry));
+      if (!file) {
+        TSWarning("cripts::Cache::Group: Failed to read entry %zu from map 
file: %s. Stopping entry load.", i, slot.path.c_str());
+        break;
+      }
+      if (!std::ranges::any_of(_slots, [&](const auto &slot) { return 
slot.map->find(entry.hash) != slot.map->end(); })) {
+        slot.map->insert_or_assign(entry.hash, entry);
+      }
+    }
+  }
+
+  // Sort the slots by creation time, newest first, since we'll start with 
index 0 upon loading
+  std::ranges::sort(_slots, [](const _MapSlot &a, const _MapSlot &b) { return 
a.created > b.created; });
+
+  // Replay any entries from the transaction log, and then truncate it
+  if (log) {
+    Cache::Group::_Entry entry;
+    auto                 last_write = cripts::Time::Clock::from_time_t(0);
+
+    while (log.read(reinterpret_cast<char *>(&entry), sizeof(entry))) {
+      _slots[0].map->insert_or_assign(entry.hash, entry);
+      last_write = std::max(last_write, entry.timestamp);
+    }
+    _slots[0].last_write = last_write;
+    clearLog();
+  }
+}
+
+void
+Cache::Group::WriteToDisk()
+{
+  std::unique_lock unique_lock(_mutex);
+
+  _last_sync = cripts::Time::Clock::now();
+  for (size_t ix = 0; ix < _slots.size(); ++ix) {
+    bool need_sync = false;
+
+    if (_slots[ix].last_write > _slots[ix].last_sync) {
+      _slots[ix].last_sync = _last_sync;
+      need_sync            = true;
+    }
+
+    if (need_sync) {
+      syncMap(ix);
+    }
+  }
+
+  clearLog();
+}
+
+//
+// Here comes the private member methods, these must never be called without
+// already holding an exclusive lock on the mutex.
+//
+
+void
+Cache::Group::appendLog(const Cache::Group::_Entry &entry)
+{
+  if (!_txn_log.is_open() || !_txn_log.good()) {
+    _txn_log.open(_log_path, std::ios::app | std::ios::out);
+    if (!_txn_log) {
+      TSWarning("cripts::Cache::Group: Failed to open transaction log `%s'.", 
_log_path.c_str());
+      return;
+    }
+  }
+
+  _txn_log.write(reinterpret_cast<const char *>(&entry), sizeof(entry));
+  _txn_log.flush();
+}
+
+void
+Cache::Group::syncMap(size_t index)
+{
+  constexpr size_t                   BUFFER_SIZE = 64 * 1024;
+  std::array<std::byte, BUFFER_SIZE> buffer;
+  size_t                             buf_pos      = 0;
+  bool                               write_failed = false;
+  const auto                        &slot         = _slots[index];
+  const std::string                  tmp_path     = slot.path + ".tmp";
+  std::ofstream                      o_file(tmp_path, std::ios::binary | 
std::ios::trunc);
+
+  if (!o_file) {
+    TSWarning("cripts::Cache::Group: Failed to open temp file for sync: %s.", 
tmp_path.c_str());
+    return;
+  }
+
+  // Helper lambda to append data to the write buffer
+  auto _AppendToBuffer = [&](const void *data, size_t size) {
+    if (write_failed) {
+      return;
+    }
+    if (buf_pos + size > buffer.size()) {
+      o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+      if (!o_file) {
+        write_failed = true;
+        return;
+      }
+      buf_pos = 0;
+    }
+    std::memcpy(buffer.data() + buf_pos, static_cast<const std::byte *>(data), 
size);
+    buf_pos += size;
+  };
+
+  _MapHeader header{.created_ts    = 
cripts::Time::Clock::to_time_t(slot.created),
+                    .last_write_ts = 
cripts::Time::Clock::to_time_t(slot.last_write),
+                    .last_sync_ts  = 
cripts::Time::Clock::to_time_t(slot.last_sync),
+                    .count         = slot.map->size()};
+
+  _AppendToBuffer(&VERSION, sizeof(VERSION));
+  _AppendToBuffer(&header, sizeof(header));
+
+  // Write entries
+  for (const auto &[_, entry] : *slot.map) {
+    _AppendToBuffer(&entry, sizeof(entry));
+  }
+
+  if (buf_pos > 0 && !write_failed) {
+    o_file.write(reinterpret_cast<const char *>(buffer.data()), buf_pos);
+  }
+  o_file.flush();
+  o_file.close();
+
+  if (write_failed || !o_file) {
+    TSWarning("cripts::Cache::Group: Failed to write to temp file `%s'.", 
tmp_path.c_str());
+    std::filesystem::remove(tmp_path);
+    return;
+  }
+
+  if (std::rename(tmp_path.c_str(), slot.path.c_str()) != 0) {
+    TSWarning("cripts::Cache::Group: Failed to rename temp file `%s' to 
`%s'.", tmp_path.c_str(), slot.path.c_str());
+    std::filesystem::remove(tmp_path);
+  }
+}
+
+void
+Cache::Group::clearLog()
+{
+  std::error_code ec;
+
+  _txn_log.close();
+  std::filesystem::remove(_log_path, ec);
+  if (ec) {
+    TSWarning("cripts::Cache::Group: Failed to clear transaction log `%s': 
%s", _log_path.c_str(), ec.message().c_str());
+  }
+}
+
+// Singleton instance for the Cache::Group::Manager
+Cache::Group::Manager &
+Cache::Group::Manager::_instance()
+{
+  static Cache::Group::Manager inst;
+  return inst;
+}
+
+void *
+Cache::Group::Manager::Factory(const std::string &name, size_t max_entries, 
size_t num_maps)
+{
+  std::lock_guard lock(_instance()._mutex);
+  auto           &groups = _instance()._groups;
+
+  if (auto it = groups.find(name); it != groups.end()) {
+    if (auto group = it->second.lock()) {
+      return new std::shared_ptr<Group>(std::move(group));
+    }
+  }
+
+  if (!_instance()._base_dir.empty()) {
+    auto group = std::make_shared<Group>(name, _instance()._base_dir, 
max_entries, num_maps);
+
+    groups[name] = group;
+    return new std::shared_ptr<Group>(std::move(group));

Review Comment:
   Memory allocated by 'new std::shared_ptr' in the Factory method could leak 
if an exception is thrown before the caller takes ownership. Consider using 
std::make_unique or returning the shared_ptr by value instead of raw pointer to 
ensure exception safety.



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