Github user zuyu commented on a diff in the pull request:
https://github.com/apache/incubator-quickstep/pull/14#discussion_r66689165
--- Diff: query_execution/PolicyEnforcer.cpp ---
@@ -0,0 +1,177 @@
+/**
+ * Copyright 2016, Quickstep Research Group, Computer Sciences
Department,
+ * University of WisconsinâMadison.
+ *
+ * Licensed 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 "query_execution/PolicyEnforcer.hpp"
+
+#include <cstddef>
+#include <memory>
+#include <queue>
+#include <utility>
+#include <unordered_map>
+#include <vector>
+
+#include "query_execution/QueryExecutionMessages.pb.h"
+#include "query_execution/QueryManager.hpp"
+#include "query_optimizer/QueryHandle.hpp"
+#include "relational_operators/WorkOrder.hpp"
+
+#include "glog/logging.h"
+
+namespace quickstep {
+
+bool PolicyEnforcer::admitQuery(QueryHandle *query_handle) {
+ if (admitted_queries_.size() < kMaxConcurrentQueries) {
+ // Ok to admit the query.
+ const std::size_t query_id = query_handle->query_id();
+ if (admitted_queries_.find(query_id) == admitted_queries_.end()) {
+ admitted_queries_[query_id].reset(
+ new QueryManager(foreman_client_id_, num_numa_nodes_,
query_handle,
+ catalog_database_, storage_manager_, bus_));
+ return true;
+ } else {
+ LOG(ERROR) << "Query with the same ID " << query_id << " exists";
+ return false;
+ }
+ } else {
+ // This query will have to wait.
+ waiting_queries_.push(query_handle);
+ return false;
--- End diff --
This is some implementation tricks to save some indentation:
```
if (...) {
if (...) {
...
return true;
}
LOG(ERROR) << ...;
return false;
}
waiting_queries_.push(query_handle);
return false;
```
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