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