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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/threading/worker_pool_posix.h"
#include "base/bind.h"
#include "base/callback.h"
#include "base/debug/trace_event.h"
#include "base/lazy_instance.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/strings/stringprintf.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_local.h"
#include "base/threading/worker_pool.h"
#include "base/tracked_objects.h"
using tracked_objects::TrackedTime;
namespace base {
namespace {
base::LazyInstance<ThreadLocalBoolean>::Leaky
g_worker_pool_running_on_this_thread = LAZY_INSTANCE_INITIALIZER;
const int kIdleSecondsBeforeExit = 10 * 60;
#ifdef ADDRESS_SANITIZER
const int kWorkerThreadStackSize = 256 * 1024;
#else
// A stack size of 64 KB is too small for the CERT_PKIXVerifyCert
// function of NSS because of NSS bug 439169.
const int kWorkerThreadStackSize = 128 * 1024;
#endif
class WorkerPoolImpl {
public:
WorkerPoolImpl();
~WorkerPoolImpl();
void PostTask(const tracked_objects::Location& from_here,
const base::Closure& task, bool task_is_slow);
private:
scoped_refptr<base::PosixDynamicThreadPool> pool_;
};
WorkerPoolImpl::WorkerPoolImpl()
: pool_(new base::PosixDynamicThreadPool("WorkerPool",
kIdleSecondsBeforeExit)) {
}
WorkerPoolImpl::~WorkerPoolImpl() {
pool_->Terminate();
}
void WorkerPoolImpl::PostTask(const tracked_objects::Location& from_here,
const base::Closure& task, bool task_is_slow) {
pool_->PostTask(from_here, task);
}
base::LazyInstance<WorkerPoolImpl> g_lazy_worker_pool =
LAZY_INSTANCE_INITIALIZER;
class WorkerThread : public PlatformThread::Delegate {
public:
WorkerThread(const std::string& name_prefix,
base::PosixDynamicThreadPool* pool)
: name_prefix_(name_prefix),
pool_(pool) {}
virtual void ThreadMain() OVERRIDE;
private:
const std::string name_prefix_;
scoped_refptr<base::PosixDynamicThreadPool> pool_;
DISALLOW_COPY_AND_ASSIGN(WorkerThread);
};
void WorkerThread::ThreadMain() {
g_worker_pool_running_on_this_thread.Get().Set(true);
const std::string name = base::StringPrintf(
"%s/%d", name_prefix_.c_str(), PlatformThread::CurrentId());
// Note |name.c_str()| must remain valid for for the whole life of the thread.
PlatformThread::SetName(name.c_str());
for (;;) {
PendingTask pending_task = pool_->WaitForTask();
if (pending_task.task.is_null())
break;
TRACE_EVENT2("task", "WorkerThread::ThreadMain::Run",
"src_file", pending_task.posted_from.file_name(),
"src_func", pending_task.posted_from.function_name());
TrackedTime start_time =
tracked_objects::ThreadData::NowForStartOfRun(pending_task.birth_tally);
pending_task.task.Run();
tracked_objects::ThreadData::TallyRunOnWorkerThreadIfTracking(
pending_task.birth_tally, TrackedTime(pending_task.time_posted),
start_time, tracked_objects::ThreadData::NowForEndOfRun());
}
// The WorkerThread is non-joinable, so it deletes itself.
delete this;
}
} // namespace
// static
bool WorkerPool::PostTask(const tracked_objects::Location& from_here,
const base::Closure& task, bool task_is_slow) {
g_lazy_worker_pool.Pointer()->PostTask(from_here, task, task_is_slow);
return true;
}
// static
bool WorkerPool::RunsTasksOnCurrentThread() {
return g_worker_pool_running_on_this_thread.Get().Get();
}
PosixDynamicThreadPool::PosixDynamicThreadPool(const std::string& name_prefix,
int idle_seconds_before_exit)
: name_prefix_(name_prefix),
idle_seconds_before_exit_(idle_seconds_before_exit),
pending_tasks_available_cv_(&lock_),
num_idle_threads_(0),
terminated_(false) {}
PosixDynamicThreadPool::~PosixDynamicThreadPool() {
while (!pending_tasks_.empty())
pending_tasks_.pop();
}
void PosixDynamicThreadPool::Terminate() {
{
AutoLock locked(lock_);
DCHECK(!terminated_) << "Thread pool is already terminated.";
terminated_ = true;
}
pending_tasks_available_cv_.Broadcast();
}
void PosixDynamicThreadPool::PostTask(
const tracked_objects::Location& from_here,
const base::Closure& task) {
PendingTask pending_task(from_here, task);
AddTask(&pending_task);
}
void PosixDynamicThreadPool::AddTask(PendingTask* pending_task) {
AutoLock locked(lock_);
DCHECK(!terminated_) <<
"This thread pool is already terminated. Do not post new tasks.";
pending_tasks_.push(*pending_task);
pending_task->task.Reset();
// We have enough worker threads.
if (static_cast<size_t>(num_idle_threads_) >= pending_tasks_.size()) {
pending_tasks_available_cv_.Signal();
} else {
// The new PlatformThread will take ownership of the WorkerThread object,
// which will delete itself on exit.
WorkerThread* worker =
new WorkerThread(name_prefix_, this);
PlatformThread::CreateNonJoinable(kWorkerThreadStackSize, worker);
}
}
PendingTask PosixDynamicThreadPool::WaitForTask() {
AutoLock locked(lock_);
if (terminated_)
return PendingTask(FROM_HERE, base::Closure());
if (pending_tasks_.empty()) { // No work available, wait for work.
num_idle_threads_++;
if (num_idle_threads_cv_.get())
num_idle_threads_cv_->Signal();
pending_tasks_available_cv_.TimedWait(
TimeDelta::FromSeconds(idle_seconds_before_exit_));
num_idle_threads_--;
if (num_idle_threads_cv_.get())
num_idle_threads_cv_->Signal();
if (pending_tasks_.empty()) {
// We waited for work, but there's still no work. Return NULL to signal
// the thread to terminate.
return PendingTask(FROM_HERE, base::Closure());
}
}
PendingTask pending_task = pending_tasks_.front();
pending_tasks_.pop();
return pending_task;
}
} // namespace base
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