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1 // Copyright 2013 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 #ifndef NET_QUIC_QUIC_ALARM_H_ | |
6 #define NET_QUIC_QUIC_ALARM_H_ | |
7 | |
8 #include <memory> | |
9 | |
10 #include "base/macros.h" | |
11 #include "net/base/net_export.h" | |
12 #include "net/quic/quic_arena_scoped_ptr.h" | |
13 #include "net/quic/quic_time.h" | |
14 | |
15 namespace net { | |
16 | |
17 // Abstract class which represents an alarm which will go off at a | |
18 // scheduled time, and execute the |OnAlarm| method of the delegate. | |
19 // An alarm may be cancelled, in which case it may or may not be | |
20 // removed from the underlying scheduling system, but in either case | |
21 // the task will not be executed. | |
22 class NET_EXPORT_PRIVATE QuicAlarm { | |
23 public: | |
24 class NET_EXPORT_PRIVATE Delegate { | |
25 public: | |
26 virtual ~Delegate() {} | |
27 | |
28 // Invoked when the alarm fires. | |
29 virtual void OnAlarm() = 0; | |
30 }; | |
31 | |
32 explicit QuicAlarm(QuicArenaScopedPtr<Delegate> delegate); | |
33 virtual ~QuicAlarm(); | |
34 | |
35 // Sets the alarm to fire at |deadline|. Must not be called while | |
36 // the alarm is set. To reschedule an alarm, call Cancel() first, | |
37 // then Set(). | |
38 void Set(QuicTime new_deadline); | |
39 | |
40 // Cancels the alarm. May be called repeatedly. Does not | |
41 // guarantee that the underlying scheduling system will remove | |
42 // the alarm's associated task, but guarantees that the | |
43 // delegates OnAlarm method will not be called. | |
44 void Cancel(); | |
45 | |
46 // Cancels and sets the alarm if the |deadline| is farther from the current | |
47 // deadline than |granularity|, and otherwise does nothing. If |deadline| is | |
48 // not initialized, the alarm is cancelled. | |
49 void Update(QuicTime new_deadline, QuicTime::Delta granularity); | |
50 | |
51 // Returns true if |deadline_| has been set to a non-zero time. | |
52 bool IsSet() const; | |
53 | |
54 QuicTime deadline() const { return deadline_; } | |
55 | |
56 protected: | |
57 // Subclasses implement this method to perform the platform-specific | |
58 // scheduling of the alarm. Is called from Set() or Fire(), after the | |
59 // deadline has been updated. | |
60 virtual void SetImpl() = 0; | |
61 | |
62 // Subclasses implement this method to perform the platform-specific | |
63 // cancelation of the alarm. | |
64 virtual void CancelImpl() = 0; | |
65 | |
66 // Subclasses implement this method to perform the platform-specific update of | |
67 // the alarm if there exists a more optimal implementation than calling | |
68 // CancelImpl() and SetImpl(). | |
69 virtual void UpdateImpl(); | |
70 | |
71 // Called by subclasses when the alarm fires. Invokes the | |
72 // delegates |OnAlarm| if a delegate is set, and if the deadline | |
73 // has been exceeded. Implementations which do not remove the | |
74 // alarm from the underlying scheduler on Cancel() may need to handle | |
75 // the situation where the task executes before the deadline has been | |
76 // reached, in which case they need to reschedule the task and must not | |
77 // call invoke this method. | |
78 void Fire(); | |
79 | |
80 private: | |
81 QuicArenaScopedPtr<Delegate> delegate_; | |
82 QuicTime deadline_; | |
83 | |
84 DISALLOW_COPY_AND_ASSIGN(QuicAlarm); | |
85 }; | |
86 | |
87 } // namespace net | |
88 | |
89 #endif // NET_QUIC_QUIC_ALARM_H_ | |
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