67 lines
2.1 KiB
C++
67 lines
2.1 KiB
C++
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// Copyright 2021 Practically.io All rights reserved
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//
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// Use of this source is governed by a BSD-style
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// licence that can be found in the LICENCE file or at
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// https://www.practically.io/copyright/
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#pragma once
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#include <condition_variable>
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#include <functional>
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#include <queue>
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#include <thread>
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namespace ivy {
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// Basic thread pool implementation to run callbacks distributed across
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// specified number of threads
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//
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// Example:
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//
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// ivy::ThreadPool thread_pool;
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// for (int i = 0; i < 10; i++) {
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// thread_pool.push([i]() {
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// std::cout << "The number is " << i << std::endl;
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// });
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// }
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//
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// thread_pool.shutdown();
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//
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class ThreadPool {
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bool m_stop = false;
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// Need to track the number of jobs that need to be processed separately
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// because we cant rely on the queue length to check if pool has finished all
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// the jobs. It dose not take into account the jobs that have already been
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// picked up by a thread.
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int m_job_count = 0;
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std::mutex m_queue_lock;
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std::queue<std::function<void()>> m_queue;
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std::mutex m_count_lock;
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std::vector<std::thread> m_threads;
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std::condition_variable m_condition;
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void run_job();
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void create_threads(unsigned int thread_count);
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public:
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// Create a new thread pool with the maximum number of threads you can have on
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// the current machine
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ThreadPool() { create_threads(std::thread::hardware_concurrency()); }
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// Create a thread pool that will use the specified number of threads
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explicit ThreadPool(unsigned int thread_count) {
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create_threads(thread_count);
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}
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// Push a call back function into the queue that will be run on the thread
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// pool as some time.
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void push(std::function<void()>);
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// Tests to see if there is any jobs that still need to be processed by the
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// queue
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bool empty();
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// Shuts down the thread pool and waits for the queue to be empty. This must
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// be called when all of the jobs have been pushed into the queue. This is a
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// blocking operation and will not exit until the queue is empty and all of
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// the pushed jobs have been handled.
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void shutdown();
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};
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} // namespace ivy
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