blob: 7608efb6093bc97d4621ba49823fa4564fc5dbf8 (
plain) (
blame)
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
126
127
128
129
130
131
132
133
134
135
136
137
|
//
// Condition.h
//
// Library: Foundation
// Package: Threading
// Module: Condition
//
// Definition of the Condition class template.
//
// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_Condition_INCLUDED
#define Foundation_Condition_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include "Poco/ScopedUnlock.h"
#include "Poco/Event.h"
#include "Poco/Exception.h"
#include <deque>
namespace Poco {
class Foundation_API Condition
/// A Condition is a synchronization object used to block a thread
/// until a particular condition is met.
/// A Condition object is always used in conjunction with
/// a Mutex (or FastMutex) object.
///
/// Condition objects are similar to POSIX condition variables, which the
/// difference that Condition is not subject to spurious wakeups.
///
/// Threads waiting on a Condition are resumed in FIFO order.
{
public:
Condition();
/// Creates the Condition.
~Condition();
/// Destroys the Condition.
template <class Mtx>
void wait(Mtx& mutex)
/// Unlocks the mutex (which must be locked upon calling
/// wait()) and waits until the Condition is signalled.
///
/// The given mutex will be locked again upon
/// leaving the function, even in case of an exception.
{
ScopedUnlock<Mtx> unlock(mutex, false);
Event event;
{
FastMutex::ScopedLock lock(_mutex);
mutex.unlock();
enqueue(event);
}
event.wait();
}
template <class Mtx>
void wait(Mtx& mutex, long milliseconds)
/// Unlocks the mutex (which must be locked upon calling
/// wait()) and waits for the given time until the Condition is signalled.
///
/// The given mutex will be locked again upon successfully leaving the
/// function, even in case of an exception.
///
/// Throws a TimeoutException if the Condition is not signalled
/// within the given time interval.
{
if (!tryWait(mutex, milliseconds))
throw TimeoutException();
}
template <class Mtx>
bool tryWait(Mtx& mutex, long milliseconds)
/// Unlocks the mutex (which must be locked upon calling
/// tryWait()) and waits for the given time until the Condition is signalled.
///
/// The given mutex will be locked again upon leaving the
/// function, even in case of an exception.
///
/// Returns true if the Condition has been signalled
/// within the given time interval, otherwise false.
{
ScopedUnlock<Mtx> unlock(mutex, false);
Event event;
{
FastMutex::ScopedLock lock(_mutex);
mutex.unlock();
enqueue(event);
}
if (!event.tryWait(milliseconds))
{
FastMutex::ScopedLock lock(_mutex);
dequeue(event);
return false;
}
return true;
}
void signal();
/// Signals the Condition and allows one waiting thread
/// to continue execution.
void broadcast();
/// Signals the Condition and allows all waiting
/// threads to continue their execution.
protected:
void enqueue(Event& event);
void dequeue();
void dequeue(Event& event);
private:
Condition(const Condition&);
Condition& operator = (const Condition&);
typedef std::deque<Event*> WaitQueue;
FastMutex _mutex;
WaitQueue _waitQueue;
};
} // namespace Poco
#endif // Foundation_Condition_INCLUDED
|
