Commit: a5beca7ba0daaca81805dbbf8857378a5bde6414
Author: Jacques Lucke
Date: Thu Apr 7 19:28:41 2022 +0200
Branches: master
https://developer.blender.org/rBa5beca7ba0daaca81805dbbf8857378a5bde6414
BLI: inline fast path of IndexRange::as_span
This frequently showed up in profiling but shouldn't.
This also updates the code to use atomics for more correctness and
adds multi-threading for better performance.
===================================================================
M source/blender/blenlib/BLI_index_range.hh
M source/blender/blenlib/BLI_span.hh
M source/blender/blenlib/intern/BLI_index_range.cc
===================================================================
diff --git a/source/blender/blenlib/BLI_index_range.hh
b/source/blender/blenlib/BLI_index_range.hh
index 85f2c83364b..7d5c2400bba 100644
--- a/source/blender/blenlib/BLI_index_range.hh
+++ b/source/blender/blenlib/BLI_index_range.hh
@@ -39,6 +39,7 @@
*/
#include <algorithm>
+#include <atomic>
#include <cmath>
#include <iostream>
@@ -288,6 +289,12 @@ class IndexRange {
stream << "[" << range.start() << ", " << range.one_after_last() << ")";
return stream;
}
+
+ private:
+ static std::atomic<int64_t> s_current_array_size;
+ static std::atomic<int64_t *> s_current_array;
+
+ Span<int64_t> as_span_internal() const;
};
} // namespace blender
diff --git a/source/blender/blenlib/BLI_span.hh
b/source/blender/blenlib/BLI_span.hh
index 9ab096094de..0f3fcea1270 100644
--- a/source/blender/blenlib/BLI_span.hh
+++ b/source/blender/blenlib/BLI_span.hh
@@ -722,4 +722,16 @@ template<typename T> class MutableSpan {
}
};
+/** This is defined here, because in `BLI_index_range.hh` `Span` is not yet
defined. */
+inline Span<int64_t> IndexRange::as_span() const
+{
+ const int64_t min_required_size = start_ + size_;
+ const int64_t current_array_size =
s_current_array_size.load(std::memory_order_acquire);
+ const int64_t *current_array =
s_current_array.load(std::memory_order_acquire);
+ if (min_required_size <= current_array_size) {
+ return Span<int64_t>(current_array + start_, size_);
+ }
+ return this->as_span_internal();
+}
+
} /* namespace blender */
diff --git a/source/blender/blenlib/intern/BLI_index_range.cc
b/source/blender/blenlib/intern/BLI_index_range.cc
index 346f55d9405..398228ab461 100644
--- a/source/blender/blenlib/intern/BLI_index_range.cc
+++ b/source/blender/blenlib/intern/BLI_index_range.cc
@@ -1,46 +1,47 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
-#include <atomic>
#include <mutex>
#include "BLI_array.hh"
#include "BLI_index_range.hh"
#include "BLI_span.hh"
+#include "BLI_task.hh"
#include "BLI_vector.hh"
namespace blender {
static RawVector<RawArray<int64_t, 0>> arrays;
-static int64_t current_array_size = 0;
-static int64_t *current_array = nullptr;
static std::mutex current_array_mutex;
+std::atomic<int64_t> IndexRange::s_current_array_size = 0;
+std::atomic<int64_t *> IndexRange::s_current_array = nullptr;
-Span<int64_t> IndexRange::as_span() const
+Span<int64_t> IndexRange::as_span_internal() const
{
int64_t min_required_size = start_ + size_;
- if (min_required_size <= current_array_size) {
- return Span<int64_t>(current_array + start_, size_);
- }
-
std::lock_guard<std::mutex> lock(current_array_mutex);
- if (min_required_size <= current_array_size) {
- return Span<int64_t>(current_array + start_, size_);
+ /* Double checked lock. */
+ if (min_required_size <= s_current_array_size) {
+ return Span<int64_t>(s_current_array + start_, size_);
}
- int64_t new_size = std::max<int64_t>(1000,
power_of_2_max_u(min_required_size));
- RawArray<int64_t, 0> new_array(new_size);
- for (int64_t i = 0; i < new_size; i++) {
- new_array[i] = i;
- }
- arrays.append(std::move(new_array));
-
- current_array = arrays.last().data();
- std::atomic_thread_fence(std::memory_order_seq_cst);
- current_array_size = new_size;
-
- return Span<int64_t>(current_array + start_, size_);
+ /* Isolate, because a mutex is locked. */
+ threading::isolate_task([&]() {
+ int64_t new_size = std::max<int64_t>(1000,
power_of_2_max_u(min_required_size));
+ RawArray<int64_t, 0> new_array(new_size);
+ threading::parallel_for(IndexRange(new_size), 4096, [&](const IndexRange
range) {
+ for (const int64_t i : range) {
+ new_array[i] = i;
+ }
+ });
+ arrays.append(std::move(new_array));
+
+ s_current_array.store(arrays.last().data(), std::memory_order_release);
+ s_current_array_size.store(new_size, std::memory_order_release);
+ });
+
+ return Span<int64_t>(s_current_array + start_, size_);
}
} // namespace blender
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