base/thread_task_runner_handle.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/thread_task_runner_handle.h"
   6
   7 #include "base/lazy_instance.h"
   8 #include "base/single_thread_task_runner.h"
   9 #include "base/threading/thread_local.h"
  10
  11 namespace base {
  12
  13 namespace {
  14
  15 base::LazyInstance<base::ThreadLocalPointer<ThreadTaskRunnerHandle> >
  16     lazy_tls_ptr = LAZY_INSTANCE_INITIALIZER;
  17
  18 }  // namespace
  19
  20 // static
  21 scoped_refptr<SingleThreadTaskRunner> ThreadTaskRunnerHandle::Get() {
  22   ThreadTaskRunnerHandle* current = lazy_tls_ptr.Pointer()->Get();
  23   DCHECK(current);
  24   return current->task_runner_;
  25 }
  26
  27 // static
  28 bool ThreadTaskRunnerHandle::IsSet() {
  29   return lazy_tls_ptr.Pointer()->Get() != NULL;
  30 }
  31
  32 ThreadTaskRunnerHandle::ThreadTaskRunnerHandle(
  33     const scoped_refptr<SingleThreadTaskRunner>& task_runner)
  34     : task_runner_(task_runner) {
  35   DCHECK(task_runner_->BelongsToCurrentThread());
  36   DCHECK(!lazy_tls_ptr.Pointer()->Get());
  37   lazy_tls_ptr.Pointer()->Set(this);
  38 }
  39
  40 ThreadTaskRunnerHandle::~ThreadTaskRunnerHandle() {
  41   DCHECK(task_runner_->BelongsToCurrentThread());
  42   DCHECK_EQ(lazy_tls_ptr.Pointer()->Get(), this);
  43   lazy_tls_ptr.Pointer()->Set(NULL);
  44 }
  45
  46 }  // namespace base