naiveproxy/base/threading/sequenced_task_runner_handle.cc
2018-08-11 05:35:24 +00:00

60 lines
1.9 KiB
C++

// 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