InitThreadFactory.h

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/*
 * Copyright 2018-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 <memory>
#include <thread>

#include <folly/ScopeGuard.h>
#include <folly/executors/thread_factory/ThreadFactory.h>

namespace folly {

class InitThreadFactory : public ThreadFactory {
 public:
  explicit InitThreadFactory(
      std::shared_ptr<ThreadFactory> threadFactory,
      Func&& threadInitializer,
      Func&& threadFinializer = [] {})
      : threadFactory_(std::move(threadFactory)),
        threadInitFini_(std::make_shared<ThreadInitFini>(
            std::move(threadInitializer),
            std::move(threadFinializer))) {}

  std::thread newThread(Func&& func) override {
    return threadFactory_->newThread(
        [func = std::move(func), threadInitFini = threadInitFini_]() mutable {
          threadInitFini->initializer();
          SCOPE_EXIT {
            threadInitFini->finalizer();
          };
          func();
        });
  }

 private:
  std::shared_ptr<ThreadFactory> threadFactory_;
  struct ThreadInitFini {
    ThreadInitFini(Func&& init, Func&& fini)
        : initializer(std::move(init)), finalizer(std::move(fini)) {}

    Func initializer;
    Func finalizer;
  };
  std::shared_ptr<ThreadInitFini> threadInitFini_;
};

} // namespace folly