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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.
#ifndef NET_QUIC_QUIC_ALARM_H_
#define NET_QUIC_QUIC_ALARM_H_
#include <memory>
#include "base/macros.h"
#include "net/base/net_export.h"
#include "net/quic/core/quic_arena_scoped_ptr.h"
#include "net/quic/core/quic_time.h"
namespace net {
// Abstract class which represents an alarm which will go off at a
// scheduled time, and execute the |OnAlarm| method of the delegate.
// An alarm may be cancelled, in which case it may or may not be
// removed from the underlying scheduling system, but in either case
// the task will not be executed.
class NET_EXPORT_PRIVATE QuicAlarm {
public:
class NET_EXPORT_PRIVATE Delegate {
public:
virtual ~Delegate() {}
// Invoked when the alarm fires.
virtual void OnAlarm() = 0;
};
explicit QuicAlarm(QuicArenaScopedPtr<Delegate> delegate);
virtual ~QuicAlarm();
// Sets the alarm to fire at |deadline|. Must not be called while
// the alarm is set. To reschedule an alarm, call Cancel() first,
// then Set().
void Set(QuicTime new_deadline);
// Cancels the alarm. May be called repeatedly. Does not
// guarantee that the underlying scheduling system will remove
// the alarm's associated task, but guarantees that the
// delegates OnAlarm method will not be called.
void Cancel();
// Cancels and sets the alarm if the |deadline| is farther from the current
// deadline than |granularity|, and otherwise does nothing. If |deadline| is
// not initialized, the alarm is cancelled.
void Update(QuicTime new_deadline, QuicTime::Delta granularity);
// Returns true if |deadline_| has been set to a non-zero time.
bool IsSet() const;
QuicTime deadline() const { return deadline_; }
protected:
// Subclasses implement this method to perform the platform-specific
// scheduling of the alarm. Is called from Set() or Fire(), after the
// deadline has been updated.
virtual void SetImpl() = 0;
// Subclasses implement this method to perform the platform-specific
// cancelation of the alarm.
virtual void CancelImpl() = 0;
// Subclasses implement this method to perform the platform-specific update of
// the alarm if there exists a more optimal implementation than calling
// CancelImpl() and SetImpl().
virtual void UpdateImpl();
// Called by subclasses when the alarm fires. Invokes the
// delegates |OnAlarm| if a delegate is set, and if the deadline
// has been exceeded. Implementations which do not remove the
// alarm from the underlying scheduler on Cancel() may need to handle
// the situation where the task executes before the deadline has been
// reached, in which case they need to reschedule the task and must not
// call invoke this method.
void Fire();
private:
QuicArenaScopedPtr<Delegate> delegate_;
QuicTime deadline_;
DISALLOW_COPY_AND_ASSIGN(QuicAlarm);
};
} // namespace net
#endif // NET_QUIC_QUIC_ALARM_H_
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