diff options
Diffstat (limited to 'src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp')
| -rw-r--r-- | src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp | 256 |
1 files changed, 201 insertions, 55 deletions
diff --git a/src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp b/src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp index f4278abcbc..500d7cc7a5 100644 --- a/src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp +++ b/src/corelib/doc/snippets/code/src_corelib_thread_qfuture.cpp @@ -1,59 +1,12 @@ -/**************************************************************************** -** -** Copyright (C) 2016 The Qt Company Ltd. -** Contact: https://www.qt.io/licensing/ -** -** This file is part of the documentation of the Qt Toolkit. -** -** $QT_BEGIN_LICENSE:BSD$ -** Commercial License Usage -** Licensees holding valid commercial Qt licenses may use this file in -** accordance with the commercial license agreement provided with the -** Software or, alternatively, in accordance with the terms contained in -** a written agreement between you and The Qt Company. For licensing terms -** and conditions see https://www.qt.io/terms-conditions. For further -** information use the contact form at https://www.qt.io/contact-us. -** -** BSD License Usage -** Alternatively, you may use this file under the terms of the BSD license -** as follows: -** -** "Redistribution and use in source and binary forms, with or without -** modification, are permitted provided that the following conditions are -** met: -** * Redistributions of source code must retain the above copyright -** notice, this list of conditions and the following disclaimer. -** * Redistributions in binary form must reproduce the above copyright -** notice, this list of conditions and the following disclaimer in -** the documentation and/or other materials provided with the -** distribution. -** * Neither the name of The Qt Company Ltd nor the names of its -** contributors may be used to endorse or promote products derived -** from this software without specific prior written permission. -** -** -** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." -** -** $QT_END_LICENSE$ -** -****************************************************************************/ +// Copyright (C) 2016 The Qt Company Ltd. +// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause //! [0] QFuture<QString> future = ...; QFuture<QString>::const_iterator i; for (i = future.constBegin(); i != future.constEnd(); ++i) - cout << *i << Qt::endl; + cout << qPrintable(*i) << endl; //! [0] @@ -62,7 +15,7 @@ QFuture<QString> future; ... QFutureIterator<QString> i(future); while (i.hasNext()) - qDebug() << i.next(); + QString s = i.next(); //! [1] @@ -70,7 +23,7 @@ while (i.hasNext()) QFutureIterator<QString> i(future); i.toBack(); while (i.hasPrevious()) - qDebug() << i.previous(); + QString s = i.previous(); //! [2] //! [3] @@ -286,11 +239,204 @@ auto future = QtConcurrent::run([] { //! [20] QObject *context = ...; -auto future = cachedResultsReady ? QtFuture::makeReadyFuture(results) - : QtConcurrent::run([] { /* compute results */}); -auto continuation = future.then(context, [] (Results results) { +auto future = cachedResultsReady ? QtFuture::makeReadyValueFuture(result) + : QtConcurrent::run([] { /* compute result */}); +auto continuation = future.then(context, [] (Result result) { // Runs in the context's thread }).then([] { // May or may not run in the context's thread }); //! [20] + +//! [21] +QFuture<int> testFuture = ...; +auto resultFuture = testFuture.then([](int res) { + // Block 1 + ... + return 1; +}).then([](int res) { + // Block 2 + ... + return 2; +}).onCanceled([] { + // Block 3 + ... + return -1; +}); +//! [21] + +//! [22] +QList<QFuture<int>> inputFutures {...}; + +// whenAll has type QFuture<QList<QFuture<int>>> +auto whenAll = QtFuture::whenAll(inputFutures.begin(), inputFutures.end()); + +// whenAllVector has type QFuture<std::vector<QFuture<int>>> +auto whenAllVector = + QtFuture::whenAll<std::vector<QFuture<int>>>(inputFutures.begin(), inputFutures.end()); +//! [22] + +//! [23] +QList<QFuture<int>> inputFutures {...}; + +QtFuture::whenAll(inputFutures.begin(), inputFutures.end()) + .then([](const QList<QFuture<int>> &results) { + for (auto future : results) { + if (future.isCanceled()) + // handle the cancellation (possibly due to an exception) + else + // do something with the result + } + }); +//! [23] + +//! [24] + +QFuture<int> intFuture = ...; +QFuture<QString> stringFuture = ...; +QFuture<void> voidFuture = ...; + +using FuturesVariant = std::variant<QFuture<int>, QFuture<QString>, QFuture<void>>; + +// whenAll has type QFuture<QList<FuturesVariant>> +auto whenAll = QtFuture::whenAll(intFuture, stringFuture, voidFuture); + +// whenAllVector has type QFuture<std::vector<FuturesVariant>> +auto whenAllVector = + QtFuture::whenAll<std::vector<FuturesVariant>>(intFuture, stringFuture, voidFuture); + +//! [24] + +//! [25] +QFuture<int> intFuture = ...; +QFuture<QString> stringFuture = ...; +QFuture<void> voidFuture = ...; + +using FuturesVariant = std::variant<QFuture<int>, QFuture<QString>, QFuture<void>>; + +QtFuture::whenAll(intFuture, stringFuture, voidFuture) + .then([](const QList<FuturesVariant> &results) { + ... + for (auto result : results) + { + // assuming handleResult() is overloaded based on the QFuture type + std::visit([](auto &&future) { handleResult(future); }, result); + } + ... + }); +//! [25] + +//! [26] +QList<QFuture<int>> inputFutures = ...; + +QtFuture::whenAny(inputFutures.begin(), inputFutures.end()) + .then([](const QtFuture::WhenAnyResult<int> &result) { + qsizetype index = result.index; + QFuture<int> future = result.future; + // ... + }); +//! [26] + +//! [27] +QFuture<int> intFuture = ...; +QFuture<QString> stringFuture = ...; +QFuture<void> voidFuture = ...; + +using FuturesVariant = std::variant<QFuture<int>, QFuture<QString>, QFuture<void>>; + +QtFuture::whenAny(intFuture, stringFuture, voidFuture).then([](const FuturesVariant &result) { + ... + // assuming handleResult() is overloaded based on the QFuture type + std::visit([](auto &&future) { handleResult(future); }, result); + ... +}); +//! [27] + +//! [28] + +QFuture<QFuture<int>> outerFuture = ...; +QFuture<int> unwrappedFuture = outerFuture.unwrap(); + +//! [28] + +//! [29] + +auto downloadImages = [] (const QUrl &url) { + QList<QImage> images; + ... + return images; +}; + +auto processImages = [](const QList<QImage> &images) { + return QtConcurrent::mappedReduced(images, scale, reduceImages); +} + +auto show = [](const QImage &image) { ... }; + +auto future = QtConcurrent::run(downloadImages, url) + .then(processImages) + .unwrap() + .then(show); +//! [29] + +//! [30] + +QFuture<QFuture<QFuture<int>>>> outerFuture; +QFuture<int> unwrappedFuture = outerFuture.unwrap(); + +//! [30] + +//! [31] +QPromise<int> p; + +QFuture<int> f1 = p.future(); +f1.then([](int) { qDebug("first"); }); + +QFuture<int> f2 = p.future(); +f2.then([](int) { qDebug("second"); }); + +p.start(); +p.addResult(42); +p.finish(); +//! [31] + +//! [32] +const std::vector<int> values{1, 2, 3}; +auto f = QtFuture::makeReadyRangeFuture(values); +//! [32] + +//! [33] +auto f = QtFuture::makeReadyRangeFuture({1, 2, 3}); +//! [33] + +//! [34] +const int count = f.resultCount(); // count == 3 +const auto results = f.results(); // results == { 1, 2, 3 } +//! [34] + +//! [35] +auto f = QtFuture::makeReadyValueFuture(std::make_unique<int>(42)); +... +const int result = *f.takeResult(); // result == 42 +//! [35] + +//! [36] +auto f = QtFuture::makeReadyVoidFuture(); +... +const bool started = f.isStarted(); // started == true +const bool running = f.isRunning(); // running == false +const bool finished = f.isFinished(); // finished == true +//! [36] + +//! [37] +QObject *context = ...; +auto future = ...; +auto continuation = future.then(context, [context](Result result) { + // ... + }).onCanceled([context = QPointer(context)] { + if (!context) + return; // context was destroyed already + // handle cancellation + }); + +//! [37] |