1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
|
// 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 QUICHE_QUIC_CORE_QUIC_ALARM_H_
#define QUICHE_QUIC_CORE_QUIC_ALARM_H_
#include "quic/core/quic_arena_scoped_ptr.h"
#include "quic/core/quic_connection_context.h"
#include "quic/core/quic_time.h"
#include "quic/platform/api/quic_export.h"
namespace quic {
// 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 QUIC_EXPORT_PRIVATE QuicAlarm {
public:
class QUIC_EXPORT_PRIVATE Delegate {
public:
virtual ~Delegate() {}
// If the alarm belongs to a single QuicConnection, return the corresponding
// QuicConnection.context_. Note the context_ is the first member of
// QuicConnection, so it should outlive the delegate.
// Otherwise return nullptr.
// The OnAlarm function will be called under the connection context, if any.
virtual QuicConnectionContext* GetConnectionContext() = 0;
// Invoked when the alarm fires.
virtual void OnAlarm() = 0;
};
// DelegateWithContext is a Delegate with a QuicConnectionContext* stored as a
// member variable.
class QUIC_EXPORT_PRIVATE DelegateWithContext : public Delegate {
public:
explicit DelegateWithContext(QuicConnectionContext* context)
: context_(context) {}
~DelegateWithContext() override {}
QuicConnectionContext* GetConnectionContext() override { return context_; }
private:
QuicConnectionContext* context_;
};
// DelegateWithoutContext is a Delegate that does not have a corresponding
// context. Typically this means one object of the child class deals with many
// connections.
class QUIC_EXPORT_PRIVATE DelegateWithoutContext : public Delegate {
public:
~DelegateWithoutContext() override {}
QuicConnectionContext* GetConnectionContext() override { return nullptr; }
};
explicit QuicAlarm(QuicArenaScopedPtr<Delegate> delegate);
QuicAlarm(const QuicAlarm&) = delete;
QuicAlarm& operator=(const QuicAlarm&) = delete;
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);
// Both PermanentCancel() and Cancel() can cancel the alarm. If permanent,
// future calls to Set() and Update() will become no-op except emitting an
// error log.
//
// Both 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 PermanentCancel() { CancelInternal(true); }
void Cancel() { CancelInternal(false); }
// Return true if PermanentCancel() has been called.
bool IsPermanentlyCancelled() const;
// 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:
void CancelInternal(bool permanent);
QuicArenaScopedPtr<Delegate> delegate_;
QuicTime deadline_;
};
} // namespace quic
#endif // QUICHE_QUIC_CORE_QUIC_ALARM_H_
|
