tvl-depot/absl/synchronization/internal/thread_pool.h
Abseil Team 83c1d65c90 Export of internal Abseil changes
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972333fe1e43427849b8a634aa35061e81be3642 by Abseil Team <absl-team@google.com>:

Replace deprecated thread annotations macros.

PiperOrigin-RevId: 267332619

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7039c6dc499a31c372b4872eda0772455931c360 by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 267220271

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a3f524d2afc2535686f206a7ce06961016349d7a by Abseil Team <absl-team@google.com>:

Factor kernel_timeout out of synchronization.

PiperOrigin-RevId: 267217304

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90287de4114ef9a06cafe50256a2d03349772c21 by Abseil Team <absl-team@google.com>:

Fixed comment typo.

PiperOrigin-RevId: 267198532

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d312c1a1e52aeca1871ff0deead416d09a7f237e by Gennadiy Rozental <rogeeff@google.com>:

Internal change

PiperOrigin-RevId: 267185804
GitOrigin-RevId: 972333fe1e43427849b8a634aa35061e81be3642
Change-Id: Ia8a2f877c57cef9854aad48f1753af872fc04dc8
2019-09-05 06:05:17 -04:00

91 lines
2.4 KiB
C++

// Copyright 2017 The Abseil Authors.
//
// 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
//
// https://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.
#ifndef ABSL_SYNCHRONIZATION_INTERNAL_THREAD_POOL_H_
#define ABSL_SYNCHRONIZATION_INTERNAL_THREAD_POOL_H_
#include <cassert>
#include <cstddef>
#include <functional>
#include <queue>
#include <thread> // NOLINT(build/c++11)
#include <vector>
#include "absl/base/thread_annotations.h"
#include "absl/synchronization/mutex.h"
namespace absl {
namespace synchronization_internal {
// A simple ThreadPool implementation for tests.
class ThreadPool {
public:
explicit ThreadPool(int num_threads) {
for (int i = 0; i < num_threads; ++i) {
threads_.push_back(std::thread(&ThreadPool::WorkLoop, this));
}
}
ThreadPool(const ThreadPool &) = delete;
ThreadPool &operator=(const ThreadPool &) = delete;
~ThreadPool() {
{
absl::MutexLock l(&mu_);
for (size_t i = 0; i < threads_.size(); i++) {
queue_.push(nullptr); // Shutdown signal.
}
}
for (auto &t : threads_) {
t.join();
}
}
// Schedule a function to be run on a ThreadPool thread immediately.
void Schedule(std::function<void()> func) {
assert(func != nullptr);
absl::MutexLock l(&mu_);
queue_.push(std::move(func));
}
private:
bool WorkAvailable() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(mu_) {
return !queue_.empty();
}
void WorkLoop() {
while (true) {
std::function<void()> func;
{
absl::MutexLock l(&mu_);
mu_.Await(absl::Condition(this, &ThreadPool::WorkAvailable));
func = std::move(queue_.front());
queue_.pop();
}
if (func == nullptr) { // Shutdown signal.
break;
}
func();
}
}
absl::Mutex mu_;
std::queue<std::function<void()>> queue_ ABSL_GUARDED_BY(mu_);
std::vector<std::thread> threads_;
};
} // namespace synchronization_internal
} // namespace absl
#endif // ABSL_SYNCHRONIZATION_INTERNAL_THREAD_POOL_H_