forked from OSchip/llvm-project
72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
//===--------------------- TaskPool.cpp -------------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/Utility/TaskPool.h"
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namespace {
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class TaskPoolImpl {
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public:
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static TaskPoolImpl &GetInstance();
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void AddTask(std::function<void()> &&task_fn);
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private:
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TaskPoolImpl();
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static void Worker(TaskPoolImpl *pool);
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std::queue<std::function<void()>> m_tasks;
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std::mutex m_tasks_mutex;
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uint32_t m_thread_count;
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};
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} // end of anonymous namespace
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TaskPoolImpl &TaskPoolImpl::GetInstance() {
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static TaskPoolImpl g_task_pool_impl;
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return g_task_pool_impl;
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}
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void TaskPool::AddTaskImpl(std::function<void()> &&task_fn) {
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TaskPoolImpl::GetInstance().AddTask(std::move(task_fn));
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}
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TaskPoolImpl::TaskPoolImpl() : m_thread_count(0) {}
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void TaskPoolImpl::AddTask(std::function<void()> &&task_fn) {
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static const uint32_t max_threads = std::thread::hardware_concurrency();
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std::unique_lock<std::mutex> lock(m_tasks_mutex);
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m_tasks.emplace(std::move(task_fn));
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if (m_thread_count < max_threads) {
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m_thread_count++;
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// Note that this detach call needs to happen with the m_tasks_mutex held.
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// This prevents the thread
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// from exiting prematurely and triggering a linux libc bug
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// (https://sourceware.org/bugzilla/show_bug.cgi?id=19951).
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std::thread(Worker, this).detach();
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}
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}
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void TaskPoolImpl::Worker(TaskPoolImpl *pool) {
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while (true) {
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std::unique_lock<std::mutex> lock(pool->m_tasks_mutex);
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if (pool->m_tasks.empty()) {
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pool->m_thread_count--;
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break;
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}
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std::function<void()> f = pool->m_tasks.front();
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pool->m_tasks.pop();
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lock.unlock();
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f();
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}
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}
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