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// 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.
#ifndef CONTENT_CHILD_SCHEDULER_CHILD_SCHEDULER_H_
#define CONTENT_CHILD_SCHEDULER_CHILD_SCHEDULER_H_
#include "base/message_loop/message_loop.h"
#include "content/child/scheduler/single_thread_idle_task_runner.h"
#include "content/common/content_export.h"
namespace base {
class MessageLoop;
}
namespace content {
class CONTENT_EXPORT ChildScheduler {
public:
virtual ~ChildScheduler() { }
// Returns the default task runner.
virtual scoped_refptr<base::SingleThreadTaskRunner> DefaultTaskRunner() = 0;
// Returns the idle task runner. Tasks posted to this runner may be reordered
// relative to other task types and may be starved for an arbitrarily long
// time if no idle time is available.
virtual scoped_refptr<SingleThreadIdleTaskRunner> IdleTaskRunner() = 0;
// Returns true if there is high priority work pending on the main thread
// and the caller should yield to let the scheduler service that work. Note
// that this is a stricter condition than |IsHighPriorityWorkAnticipated|,
// restricted to the case where real work is pending.
// Must be called from the thread this scheduler was created on.
virtual bool ShouldYieldForHighPriorityWork() = 0;
// Returns true if a currently running idle task could exceed its deadline
// without impacting user experience too much. This should only be used if
// there is a task which cannot be pre-empted and is likely to take longer
// than the largest expected idle task deadline. It should NOT be polled to
// check whether more work can be performed on the current idle task after
// its deadline has expired - post a new idle task for the continuation of the
// work in this case.
// Must be called from the thread this scheduler was created on.
virtual bool CanExceedIdleDeadlineIfRequired() const = 0;
// Adds or removes a task observer from the scheduler. The observer will be
// notified before and after every executed task. These functions can only be
// called on the thread this scheduler was created on.
virtual void AddTaskObserver(
base::MessageLoop::TaskObserver* task_observer) = 0;
virtual void RemoveTaskObserver(
base::MessageLoop::TaskObserver* task_observer) = 0;
// Shuts down the scheduler by dropping any remaining pending work in the work
// queues. After this call any work posted to the task runners will be
// silently dropped.
virtual void Shutdown() = 0;
protected:
ChildScheduler() { }
DISALLOW_COPY_AND_ASSIGN(ChildScheduler);
};
} // namespace content
#endif // CONTENT_CHILD_SCHEDULER_CHILD_SCHEDULER_H_
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