executor with priority

Summary: make an adapter executor that forwards add to addWithPriority of the underlying executor

Reviewed By: andriigrynenko

Differential Revision: D13788642

fbshipit-source-id: 5b4af43f4a3a3931817a2425890558f811152225

folly/executors/ExecutorWithPriority.cpp

+/*
+ * Copyright 2019-present Facebook, Inc.
+ *
+ * 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 <folly/executors/ExecutorWithPriority.h>
+#include <glog/logging.h>
+
+namespace folly {
+Executor::KeepAlive<ExecutorWithPriority> ExecutorWithPriority::create(
+    KeepAlive<Executor> executor,
+    int8_t priority) {
+  return makeKeepAlive<ExecutorWithPriority>(
+      new ExecutorWithPriority(std::move(executor), priority));
+}
+
+void ExecutorWithPriority::add(Func func) {
+  executor_->addWithPriority(std::move(func), priority_);
+}
+
+bool ExecutorWithPriority::keepAliveAcquire() {
+  auto keepAliveCounter =
+      keepAliveCounter_.fetch_add(1, std::memory_order_relaxed);
+  DCHECK(keepAliveCounter > 0);
+  return true;
+}
+
+void ExecutorWithPriority::keepAliveRelease() {
+  auto keepAliveCounter =
+      keepAliveCounter_.fetch_sub(1, std::memory_order_acq_rel);
+  DCHECK(keepAliveCounter > 0);
+  if (keepAliveCounter == 1) {
+    delete this;
+  }
+}
+} // namespace folly

folly/executors/ExecutorWithPriority.h

+/*
+ * Copyright 2017-present Facebook, Inc.
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <folly/Executor.h>
+#include <atomic>
+
+namespace folly {
+
+class ExecutorWithPriority : public virtual Executor {
+ public:
+  ExecutorWithPriority(ExecutorWithPriority const&) = delete;
+  ExecutorWithPriority& operator=(ExecutorWithPriority const&) = delete;
+  ExecutorWithPriority(ExecutorWithPriority&&) = delete;
+  ExecutorWithPriority& operator=(ExecutorWithPriority&&) = delete;
+
+  static Executor::KeepAlive<ExecutorWithPriority> create(
+      KeepAlive<Executor> executor,
+      int8_t priority);
+
+  void add(Func func) override;
+
+ protected:
+  bool keepAliveAcquire() override;
+  void keepAliveRelease() override;
+
+ private:
+  ExecutorWithPriority(KeepAlive<Executor> executor, int8_t priority)
+      : executor_(std::move(executor)), priority_(priority) {}
+
+  std::atomic<ssize_t> keepAliveCounter_{1};
+  KeepAlive<Executor> executor_;
+  int8_t priority_;
+};
+} // namespace folly

folly/executors/test/ExecutorWithPriorityTest.cpp

+/*
+ * Copyright 2019-present Facebook, Inc.
+ *
+ * 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 <folly/executors/ExecutorWithPriority.h>
+#include <folly/executors/CPUThreadPoolExecutor.h>
+#include <folly/portability/GTest.h>
+
+using namespace folly;
+
+TEST(ExecutorWithPriorityTest, addWithCorrectPriorityTest) {
+  bool tookLopri = false;
+  auto completed = 0;
+  auto hipri = [&] {
+    EXPECT_FALSE(tookLopri);
+    completed++;
+  };
+  auto lopri = [&] {
+    tookLopri = true;
+    completed++;
+  };
+  auto pool = std::make_shared<CPUThreadPoolExecutor>(
+      0 /*numThreads*/, 2 /*numPriorities*/);
+  {
+    auto loPriExecutor = ExecutorWithPriority::create(
+        getKeepAliveToken(pool.get()), Executor::LO_PRI);
+    auto hiPriExecutor = ExecutorWithPriority::create(
+        getKeepAliveToken(pool.get()), Executor::HI_PRI);
+    for (int i = 0; i < 50; i++) {
+      loPriExecutor->add(lopri);
+    }
+    for (int i = 0; i < 50; i++) {
+      hiPriExecutor->add(hipri);
+    }
+    pool->setNumThreads(1);
+  }
+  pool->join();
+  EXPECT_EQ(100, completed);
+}