| /**************************************************************************** |
| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
| ** Contact: https://www.qt.io/licensing/ |
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| ** This file is part of the documentation of the Qt Toolkit. |
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| ** $QT_BEGIN_LICENSE:BSD$ |
| ** Commercial License Usage |
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| ** BSD License Usage |
| ** Alternatively, you may use this file under the terms of the BSD license |
| ** as follows: |
| ** |
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| ** modification, are permitted provided that the following conditions are |
| ** met: |
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| ****************************************************************************/ |
| |
| //! [0] |
| int number = 6; |
| |
| void method1() |
| { |
| number *= 5; |
| number /= 4; |
| } |
| |
| void method2() |
| { |
| number *= 3; |
| number /= 2; |
| } |
| //! [0] |
| |
| |
| //! [1] |
| // method1() |
| number *= 5; // number is now 30 |
| number /= 4; // number is now 7 |
| |
| // method2() |
| number *= 3; // number is now 21 |
| number /= 2; // number is now 10 |
| //! [1] |
| |
| |
| //! [2] |
| // Thread 1 calls method1() |
| number *= 5; // number is now 30 |
| |
| // Thread 2 calls method2(). |
| // |
| // Most likely Thread 1 has been put to sleep by the operating |
| // system to allow Thread 2 to run. |
| number *= 3; // number is now 90 |
| number /= 2; // number is now 45 |
| |
| // Thread 1 finishes executing. |
| number /= 4; // number is now 11, instead of 10 |
| //! [2] |
| |
| |
| //! [3] |
| QMutex mutex; |
| int number = 6; |
| |
| void method1() |
| { |
| mutex.lock(); |
| number *= 5; |
| number /= 4; |
| mutex.unlock(); |
| } |
| |
| void method2() |
| { |
| mutex.lock(); |
| number *= 3; |
| number /= 2; |
| mutex.unlock(); |
| } |
| //! [3] |
| |
| |
| //! [4] |
| int complexFunction(int flag) |
| { |
| mutex.lock(); |
| |
| int retVal = 0; |
| |
| switch (flag) { |
| case 0: |
| case 1: |
| retVal = moreComplexFunction(flag); |
| break; |
| case 2: |
| { |
| int status = anotherFunction(); |
| if (status < 0) { |
| mutex.unlock(); |
| return -2; |
| } |
| retVal = status + flag; |
| } |
| break; |
| default: |
| if (flag > 10) { |
| mutex.unlock(); |
| return -1; |
| } |
| break; |
| } |
| |
| mutex.unlock(); |
| return retVal; |
| } |
| //! [4] |
| |
| |
| //! [5] |
| int complexFunction(int flag) |
| { |
| QMutexLocker locker(&mutex); |
| |
| int retVal = 0; |
| |
| switch (flag) { |
| case 0: |
| case 1: |
| return moreComplexFunction(flag); |
| case 2: |
| { |
| int status = anotherFunction(); |
| if (status < 0) |
| return -2; |
| retVal = status + flag; |
| } |
| break; |
| default: |
| if (flag > 10) |
| return -1; |
| break; |
| } |
| |
| return retVal; |
| } |
| //! [5] |
| |
| |
| //! [6] |
| class SignalWaiter |
| { |
| private: |
| QMutexLocker locker; |
| |
| public: |
| SignalWaiter(QMutex *mutex) |
| : locker(mutex) |
| { |
| } |
| |
| void waitForSignal() |
| { |
| ... |
| while (!signalled) |
| waitCondition.wait(locker.mutex()); |
| ... |
| } |
| }; |
| //! [6] |