// Copyright 2015 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/sequenced_task_runner_handle.h"
|
|
#include <utility>
|
|
#include "base/lazy_instance.h"
|
#include "base/logging.h"
|
#include "base/threading/thread_local.h"
|
#include "base/threading/thread_task_runner_handle.h"
|
|
namespace base {
|
|
namespace {
|
|
LazyInstance<ThreadLocalPointer<SequencedTaskRunnerHandle>>::Leaky
|
sequenced_task_runner_tls = LAZY_INSTANCE_INITIALIZER;
|
|
} // namespace
|
|
// static
|
scoped_refptr<SequencedTaskRunner> SequencedTaskRunnerHandle::Get() {
|
// Return the registered SequencedTaskRunner, if any.
|
const SequencedTaskRunnerHandle* handle =
|
sequenced_task_runner_tls.Pointer()->Get();
|
if (handle)
|
return handle->task_runner_;
|
|
// Note if you hit this: the problem is the lack of a sequenced context. The
|
// ThreadTaskRunnerHandle is just the last attempt at finding such a context.
|
CHECK(ThreadTaskRunnerHandle::IsSet())
|
<< "Error: This caller requires a sequenced context (i.e. the "
|
"current task needs to run from a SequencedTaskRunner).";
|
return ThreadTaskRunnerHandle::Get();
|
}
|
|
// static
|
bool SequencedTaskRunnerHandle::IsSet() {
|
return sequenced_task_runner_tls.Pointer()->Get() ||
|
ThreadTaskRunnerHandle::IsSet();
|
}
|
|
SequencedTaskRunnerHandle::SequencedTaskRunnerHandle(
|
scoped_refptr<SequencedTaskRunner> task_runner)
|
: task_runner_(std::move(task_runner)) {
|
DCHECK(task_runner_->RunsTasksInCurrentSequence());
|
DCHECK(!SequencedTaskRunnerHandle::IsSet());
|
sequenced_task_runner_tls.Pointer()->Set(this);
|
}
|
|
SequencedTaskRunnerHandle::~SequencedTaskRunnerHandle() {
|
DCHECK(task_runner_->RunsTasksInCurrentSequence());
|
DCHECK_EQ(sequenced_task_runner_tls.Pointer()->Get(), this);
|
sequenced_task_runner_tls.Pointer()->Set(nullptr);
|
}
|
|
} // namespace base
|
