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
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
|
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the either Technology Preview License Agreement or the
** Beta Release License Agreement.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain
** additional rights. These rights are described in the Nokia Qt LGPL
** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
** package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you are unsure which license is appropriate for your use, please
** contact the sales department at http://www.qtsoftware.com/contact.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef QTCONCURRENT_THREADENGINE_H
#define QTCONCURRENT_THREADENGINE_H
#include <QtCore/qglobal.h>
#ifndef QT_NO_CONCURRENT
#include <QtCore/qthreadpool.h>
#include <QtCore/qfuture.h>
#include <QtCore/qdebug.h>
#include <QtCore/qtconcurrentexception.h>
#include <QtCore/qwaitcondition.h>
#include <QtCore/qatomic.h>
#include <QtCore/qsemaphore.h>
QT_BEGIN_HEADER
QT_BEGIN_NAMESPACE
QT_MODULE(Core)
#ifndef qdoc
namespace QtConcurrent {
// The ThreadEngineBarrier counts worker threads, and allows one
// thread to wait for all others to finish. Tested for its use in
// QtConcurrent, requires more testing for use as a general class.
class ThreadEngineBarrier
{
private:
// The thread count is maintained as an integer in the count atomic
// variable. The count can be either positive or negative - a negative
// count signals that a thread is waiting on the barrier.
// BC note: inlined code from Qt < 4.6 will expect to find the QMutex
// and QAtomicInt here. ### Qt 5: remove.
QMutex mutex;
QAtomicInt count;
QSemaphore semaphore;
public:
ThreadEngineBarrier();
void acquire();
int release();
void wait();
int currentCount();
bool releaseUnlessLast();
};
enum ThreadFunctionResult { ThrottleThread, ThreadFinished };
// The ThreadEngine controls the threads used in the computation.
// Can be run in three modes: single threaded, multi-threaded blocking
// and multi-threaded asynchronous.
// The code for the single threaded mode is
class Q_CORE_EXPORT ThreadEngineBase: public QRunnable
{
public:
// Public API:
ThreadEngineBase();
virtual ~ThreadEngineBase();
void startSingleThreaded();
void startBlocking();
void startThread();
bool isCanceled();
void waitForResume();
bool isProgressReportingEnabled();
void setProgressValue(int progress);
void setProgressRange(int minimum, int maximum);
void acquireBarrierSemaphore();
protected: // The user overrides these:
virtual void start() {}
virtual void finish() {}
virtual ThreadFunctionResult threadFunction() { return ThreadFinished; }
virtual bool shouldStartThread() { return futureInterface ? !futureInterface->isPaused() : true; }
virtual bool shouldThrottleThread() { return futureInterface ? futureInterface->isPaused() : false; }
private:
bool startThreadInternal();
void startThreads();
void threadExit();
bool threadThrottleExit();
void run();
virtual void asynchronousFinish() = 0;
#ifndef QT_NO_EXCEPTIONS
void handleException(const QtConcurrent::Exception &exception);
#endif
protected:
QFutureInterfaceBase *futureInterface;
QThreadPool *threadPool;
ThreadEngineBarrier barrier;
QtConcurrent::internal::ExceptionStore exceptionStore;
};
template <typename T>
class ThreadEngine : public virtual ThreadEngineBase
{
public:
typedef T ResultType;
virtual T *result() { return 0; }
QFutureInterface<T> *futureInterfaceTyped()
{
return static_cast<QFutureInterface<T> *>(futureInterface);
}
// Runs the user algorithm using a single thread.
T *startSingleThreaded()
{
ThreadEngineBase::startSingleThreaded();
return result();
}
// Runs the user algorithm using multiple threads.
// This function blocks until the algorithm is finished,
// and then returns the result.
T *startBlocking()
{
ThreadEngineBase::startBlocking();
return result();
}
// Runs the user algorithm using multiple threads.
// Does not block, returns a future.
QFuture<T> startAsynchronously()
{
futureInterface = new QFutureInterface<T>();
// reportStart() must be called before starting threads, otherwise the
// user algorithm might finish while reportStart() is running, which
// is very bad.
futureInterface->reportStarted();
QFuture<T> future = QFuture<T>(futureInterfaceTyped());
start();
acquireBarrierSemaphore();
threadPool->start(this);
return future;
}
void asynchronousFinish()
{
finish();
futureInterfaceTyped()->reportFinished(result());
delete futureInterfaceTyped();
delete this;
}
void reportResult(const T *_result, int index = -1)
{
if (futureInterface)
futureInterfaceTyped()->reportResult(_result, index);
}
void reportResults(const QVector<T> &_result, int index = -1, int count = -1)
{
if (futureInterface)
futureInterfaceTyped()->reportResults(_result, index, count);
}
};
// The ThreadEngineStarter class ecapsulates the return type
// from the thread engine.
// Depending on how the it is used, it will run
// the engine in either blocking mode or asynchronous mode.
template <typename T>
class ThreadEngineStarterBase
{
public:
ThreadEngineStarterBase(ThreadEngine<T> *_threadEngine)
: threadEngine(_threadEngine) { }
inline ThreadEngineStarterBase(const ThreadEngineStarterBase &other)
: threadEngine(other.threadEngine) { }
QFuture<T> startAsynchronously()
{
return threadEngine->startAsynchronously();
}
operator QFuture<T>()
{
return startAsynchronously();
}
protected:
ThreadEngine<T> *threadEngine;
};
// We need to factor out the code that dereferences the T pointer,
// with a specialization where T is void. (code that dereferences a void *
// won't compile)
template <typename T>
class ThreadEngineStarter : public ThreadEngineStarterBase<T>
{
typedef ThreadEngineStarterBase<T> Base;
typedef ThreadEngine<T> TypedThreadEngine;
public:
ThreadEngineStarter(TypedThreadEngine *eng)
: Base(eng) { }
T startBlocking()
{
T t = *this->threadEngine->startBlocking();
delete this->threadEngine;
return t;
}
};
// Full template specialization where T is void.
template <>
class ThreadEngineStarter<void> : public ThreadEngineStarterBase<void>
{
public:
ThreadEngineStarter<void>(ThreadEngine<void> *_threadEngine)
:ThreadEngineStarterBase<void>(_threadEngine) {}
void startBlocking()
{
this->threadEngine->startBlocking();
delete this->threadEngine;
}
};
template <typename ThreadEngine>
inline ThreadEngineStarter<typename ThreadEngine::ResultType> startThreadEngine(ThreadEngine *threadEngine)
{
return ThreadEngineStarter<typename ThreadEngine::ResultType>(threadEngine);
}
} // namespace QtConcurrent
#endif //qdoc
QT_END_NAMESPACE
QT_END_HEADER
#endif // QT_NO_CONCURRENT
#endif
|