1 /****************************************************************************
2 **
3 ** Copyright (C) 2016 The Qt Company Ltd.
4 ** Contact: https://www.qt.io/licensing/
5 **
6 ** This file is part of the QtCore module of the Qt Toolkit.
7 **
8 ** $QT_BEGIN_LICENSE:LGPL$
9 ** Commercial License Usage
10 ** Licensees holding valid commercial Qt licenses may use this file in
11 ** accordance with the commercial license agreement provided with the
12 ** Software or, alternatively, in accordance with the terms contained in
13 ** a written agreement between you and The Qt Company. For licensing terms
14 ** and conditions see https://www.qt.io/terms-conditions. For further
15 ** information use the contact form at https://www.qt.io/contact-us.
16 **
17 ** GNU Lesser General Public License Usage
18 ** Alternatively, this file may be used under the terms of the GNU Lesser
19 ** General Public License version 3 as published by the Free Software
20 ** Foundation and appearing in the file LICENSE.LGPL3 included in the
21 ** packaging of this file. Please review the following information to
22 ** ensure the GNU Lesser General Public License version 3 requirements
23 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
24 **
25 ** GNU General Public License Usage
26 ** Alternatively, this file may be used under the terms of the GNU
27 ** General Public License version 2.0 or (at your option) the GNU General
28 ** Public license version 3 or any later version approved by the KDE Free
29 ** Qt Foundation. The licenses are as published by the Free Software
30 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
31 ** included in the packaging of this file. Please review the following
32 ** information to ensure the GNU General Public License requirements will
33 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and
34 ** https://www.gnu.org/licenses/gpl-3.0.html.
35 **
36 ** $QT_END_LICENSE$
37 **
38 ****************************************************************************/
39 
40 #ifndef QTHREADPOOL_P_H
41 #define QTHREADPOOL_P_H
42 
43 //
44 //  W A R N I N G
45 //  -------------
46 //
47 // This file is not part of the Qt API.  It exists purely as an
48 // implementation detail.  This header file may change from version to
49 // version without notice, or even be removed.
50 //
51 // We mean it.
52 //
53 //
54 
55 #include "QtCore/qmutex.h"
56 #include "QtCore/qthread.h"
57 #include "QtCore/qwaitcondition.h"
58 #include "QtCore/qset.h"
59 #include "QtCore/qqueue.h"
60 #include "private/qobject_p.h"
61 
62 QT_REQUIRE_CONFIG(thread);
63 
64 QT_BEGIN_NAMESPACE
65 
66 class QDeadlineTimer;
67 
68 class QueuePage {
69 public:
70     enum {
71         MaxPageSize = 256
72     };
73 
QueuePage(QRunnable * runnable,int pri)74     QueuePage(QRunnable *runnable, int pri)
75         : m_priority(pri)
76     {
77         push(runnable);
78     }
79 
isFull()80     bool isFull() {
81         return m_lastIndex >= MaxPageSize - 1;
82     }
83 
isFinished()84     bool isFinished() {
85         return m_firstIndex > m_lastIndex;
86     }
87 
push(QRunnable * runnable)88     void push(QRunnable *runnable) {
89         Q_ASSERT(runnable != nullptr);
90         Q_ASSERT(!isFull());
91         m_lastIndex += 1;
92         m_entries[m_lastIndex] = runnable;
93     }
94 
skipToNextOrEnd()95     void skipToNextOrEnd() {
96         while (!isFinished() && m_entries[m_firstIndex] == nullptr) {
97             m_firstIndex += 1;
98         }
99     }
100 
first()101     QRunnable *first() {
102         Q_ASSERT(!isFinished());
103         QRunnable *runnable = m_entries[m_firstIndex];
104         Q_ASSERT(runnable);
105         return runnable;
106     }
107 
pop()108     QRunnable *pop() {
109         Q_ASSERT(!isFinished());
110         QRunnable *runnable = first();
111         Q_ASSERT(runnable);
112 
113         // clear the entry although this should not be necessary
114         m_entries[m_firstIndex] = nullptr;
115         m_firstIndex += 1;
116 
117         // make sure the next runnable returned by first() is not a nullptr
118         skipToNextOrEnd();
119 
120         return runnable;
121     }
122 
tryTake(QRunnable * runnable)123     bool tryTake(QRunnable *runnable) {
124         Q_ASSERT(!isFinished());
125         for (int i = m_firstIndex; i <= m_lastIndex; i++) {
126             if (m_entries[i] == runnable) {
127                 m_entries[i] = nullptr;
128                 if (i == m_firstIndex) {
129                     // make sure first() does not return a nullptr
130                     skipToNextOrEnd();
131                 }
132                 return true;
133             }
134         }
135         return false;
136     }
137 
priority()138     int priority() const {
139         return m_priority;
140     }
141 
142 private:
143     int m_priority = 0;
144     int m_firstIndex = 0;
145     int m_lastIndex = -1;
146     QRunnable *m_entries[MaxPageSize];
147 };
148 
149 class QThreadPoolThread;
150 class Q_CORE_EXPORT QThreadPoolPrivate : public QObjectPrivate
151 {
152     Q_DECLARE_PUBLIC(QThreadPool)
153     friend class QThreadPoolThread;
154 
155 public:
156     QThreadPoolPrivate();
157 
158     bool tryStart(QRunnable *task);
159     void enqueueTask(QRunnable *task, int priority = 0);
160     int activeThreadCount() const;
161 
162     void tryToStartMoreThreads();
163     bool tooManyThreadsActive() const;
164 
165     void startThread(QRunnable *runnable = nullptr);
166     void reset();
167     bool waitForDone(int msecs);
168     bool waitForDone(const QDeadlineTimer &timer);
169     void clear();
170     void stealAndRunRunnable(QRunnable *runnable);
171     void deletePageIfFinished(QueuePage *page);
172 
173     mutable QMutex mutex;
174     QSet<QThreadPoolThread *> allThreads;
175     QQueue<QThreadPoolThread *> waitingThreads;
176     QQueue<QThreadPoolThread *> expiredThreads;
177     QVector<QueuePage*> queue;
178     QWaitCondition noActiveThreads;
179 
180     int expiryTimeout = 30000;
181     int maxThreadCount = QThread::idealThreadCount();
182     int reservedThreads = 0;
183     int activeThreads = 0;
184     uint stackSize = 0;
185 };
186 
187 QT_END_NAMESPACE
188 
189 #endif
190