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// Copyright 2013 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/base_export.h"
#include "base/memory/ref_counted.h"
#include "base/pending_task.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
namespace base {
class MessageLoop;
class WaitableEvent;
namespace internal {
// Implements a queue of tasks posted to the message loop running on the current
// thread. This class takes care of synchronizing posting tasks from different
// threads and together with MessageLoop ensures clean shutdown.
class BASE_EXPORT IncomingTaskQueue
: public RefCountedThreadSafe<IncomingTaskQueue> {
explicit IncomingTaskQueue(MessageLoop* message_loop);
// Appends a task to the incoming queue. Posting of all tasks is routed though
// AddToIncomingQueue() or TryAddToIncomingQueue() to make sure that posting
// task is properly synchronized between different threads.
// Returns true if the task was successfully added to the queue, otherwise
// returns false. In all cases, the ownership of |task| is transferred to the
// called method.
bool AddToIncomingQueue(const tracked_objects::Location& from_here,
const Closure& task,
TimeDelta delay,
bool nestable);
// Returns true if the message loop has high resolution timers enabled.
// Provided for testing.
bool IsHighResolutionTimerEnabledForTesting();
// Returns true if the message loop is "idle". Provided for testing.
bool IsIdleForTesting();
// Loads tasks from the |incoming_queue_| into |*work_queue|. Must be called
// from the thread that is running the loop.
void ReloadWorkQueue(TaskQueue* work_queue);
// Disconnects |this| from the parent message loop.
void WillDestroyCurrentMessageLoop();
friend class RefCountedThreadSafe<IncomingTaskQueue>;
virtual ~IncomingTaskQueue();
// Calculates the time at which a PendingTask should run.
TimeTicks CalculateDelayedRuntime(TimeDelta delay);
// Adds a task to |incoming_queue_|. The caller retains ownership of
// |pending_task|, but this function will reset the value of
// |pending_task->task|. This is needed to ensure that the posting call stack
// does not retain |pending_task->task| beyond this function call.
bool PostPendingTask(PendingTask* pending_task);
#if defined(OS_WIN)
TimeTicks high_resolution_timer_expiration_;
// The lock that protects access to |incoming_queue_|, |message_loop_| and
// |next_sequence_num_|.
base::Lock incoming_queue_lock_;
// An incoming queue of tasks that are acquired under a mutex for processing
// on this instance's thread. These tasks have not yet been been pushed to
// |message_loop_|.
TaskQueue incoming_queue_;
// Points to the message loop that owns |this|.
MessageLoop* message_loop_;
// The next sequence number to use for delayed tasks.
int next_sequence_num_;
} // namespace internal
} // namespace base