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a301964bd0
Thereby avoids a race condition.
106 lines
2.6 KiB
C++
106 lines
2.6 KiB
C++
//
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// AsyncTaskQueue.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 07/10/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "AsyncTaskQueue.hpp"
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using namespace Concurrency;
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AsyncTaskQueue::AsyncTaskQueue()
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#ifndef __APPLE__
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: should_destruct_(false)
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#endif
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{
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#ifdef __APPLE__
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serial_dispatch_queue_ = dispatch_queue_create("com.thomasharte.clocksignal.asyntaskqueue", DISPATCH_QUEUE_SERIAL);
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#else
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thread_.reset(new std::thread([this]() {
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while(!should_destruct_) {
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std::function<void(void)> next_function;
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// Take lock, check for a new task
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std::unique_lock<std::mutex> lock(queue_mutex_);
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if(!pending_tasks_.empty()) {
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next_function = pending_tasks_.front();
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pending_tasks_.pop_front();
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}
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if(next_function) {
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// If there is a task, release lock and perform it
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lock.unlock();
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next_function();
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} else {
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// If there isn't a task, atomically block on the processing condition and release the lock
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// until there's something pending (and then release it again via scope)
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processing_condition_.wait(lock);
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}
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}
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}));
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#endif
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}
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AsyncTaskQueue::~AsyncTaskQueue() {
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#ifdef __APPLE__
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flush();
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dispatch_release(serial_dispatch_queue_);
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serial_dispatch_queue_ = nullptr;
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#else
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should_destruct_ = true;
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enqueue([](){});
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thread_->join();
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thread_.reset();
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#endif
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}
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void AsyncTaskQueue::enqueue(std::function<void(void)> function) {
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#ifdef __APPLE__
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dispatch_async(serial_dispatch_queue_, ^{function();});
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#else
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std::lock_guard<std::mutex> lock(queue_mutex_);
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pending_tasks_.push_back(function);
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processing_condition_.notify_all();
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#endif
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}
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void AsyncTaskQueue::flush() {
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#ifdef __APPLE__
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dispatch_sync(serial_dispatch_queue_, ^{});
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#else
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std::shared_ptr<std::mutex> flush_mutex(new std::mutex);
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std::shared_ptr<std::condition_variable> flush_condition(new std::condition_variable);
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std::unique_lock<std::mutex> lock(*flush_mutex);
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enqueue([=] () {
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std::unique_lock<std::mutex> inner_lock(*flush_mutex);
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flush_condition->notify_all();
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});
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flush_condition->wait(lock);
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#endif
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}
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DeferringAsyncTaskQueue::~DeferringAsyncTaskQueue() {
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perform();
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flush();
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}
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void DeferringAsyncTaskQueue::defer(std::function<void(void)> function) {
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if(!deferred_tasks_) {
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deferred_tasks_.reset(new std::list<std::function<void(void)>>);
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}
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deferred_tasks_->push_back(function);
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}
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void DeferringAsyncTaskQueue::perform() {
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if(!deferred_tasks_) return;
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std::shared_ptr<std::list<std::function<void(void)>>> deferred_tasks = deferred_tasks_;
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deferred_tasks_.reset();
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enqueue([deferred_tasks] {
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for(auto &function : *deferred_tasks) {
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function();
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}
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});
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}
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