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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
//! [0]
QSemaphore sem(5); // sem.available() == 5
sem.acquire(3); // sem.available() == 2
sem.acquire(2); // sem.available() == 0
sem.release(5); // sem.available() == 5
sem.release(5); // sem.available() == 10
sem.tryAcquire(1); // sem.available() == 9, returns true
sem.tryAcquire(250); // sem.available() == 9, returns false
//! [0]
//! [1]
QSemaphore sem(5); // a semaphore that guards 5 resources
sem.acquire(5); // acquire all 5 resources
sem.release(5); // release the 5 resources
sem.release(10); // "create" 10 new resources
//! [1]
//! [2]
QSemaphore sem(5); // sem.available() == 5
sem.tryAcquire(250); // sem.available() == 5, returns false
sem.tryAcquire(3); // sem.available() == 2, returns true
//! [2]
//! [3]
QSemaphore sem(5); // sem.available() == 5
sem.tryAcquire(250, 1000); // sem.available() == 5, waits 1000 milliseconds and returns false
sem.tryAcquire(3, 30000); // sem.available() == 2, returns true without waiting
//! [3]
//! [tryAcquire-QDeadlineTimer]
QSemaphore sem(5); // sem.available() == 5
sem.tryAcquire(250, QDeadlineTimer(1000)); // sem.available() == 5, waits 1000 milliseconds and returns false
sem.tryAcquire(3, QDeadlineTimer(30s)); // sem.available() == 2, returns true without waiting
//! [tryAcquire-QDeadlineTimer]
//! [4]
// ... do something that may throw or return early
sem.release();
//! [4]
//! [5]
const QSemaphoreReleaser releaser(sem);
// ... do something that may throw or early return
// implicitly calls sem.release() here and at every other return in between
//! [5]
//! [6]
{ // some scope
QSemaphoreReleaser releaser; // does nothing
// ...
if (someCondition) {
releaser = QSemaphoreReleaser(sem);
// ...
}
// ...
} // conditionally calls sem.release(), depending on someCondition
//! [6]
//! [7]
releaser.cancel(); // avoid releasing old semaphore()
releaser = QSemaphoreReleaser(sem, 42);
// now will call sem.release(42) when 'releaser' is destroyed
//! [7]
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