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Diffstat (limited to 'src/corelib/doc/src/threads.qdoc')
| -rw-r--r-- | src/corelib/doc/src/threads.qdoc | 56 |
1 files changed, 55 insertions, 1 deletions
diff --git a/src/corelib/doc/src/threads.qdoc b/src/corelib/doc/src/threads.qdoc index 3d11c736cf..79bd7a62a3 100644 --- a/src/corelib/doc/src/threads.qdoc +++ b/src/corelib/doc/src/threads.qdoc @@ -178,7 +178,14 @@ See the \l{Qt Concurrent} module documentation for details on the individual functions. - \section1 Comparison of Solutions + \section1 Choosing an Appropriate Approach + + As demonstrated above, Qt provides different solutions for developing threaded + applications. The right solution for a given application depends on the purpose + of the new thread and the thread's lifetime. Below is a comparison of Qt's + threading technologies, followed by recommended solutions for some example use cases. + + \section2 Comparison of Solutions \table \header @@ -228,6 +235,53 @@ \li Yes \endtable \sup{\e{*Except QtConcurrent::run(), which is like QRunnable}} + + + \section2 Example Use Cases + + \table + \header + \li Lifetime of thread + \li Operation + \li Solution + \row + \li One call + \li Run a linear function within another thread, optionally with progress + updates during the run. + \li Qt provides different solutions: + \list + \li Place the function in a reimplementation of QThread::run() and + start the QThread. Emit signals to update progress. OR + \li Place the function in a reimplementation of QRunnable::run() and + add the QRunnable to a QThreadPool. Write to a \l{Synchronizing + Threads}{thread-safe variable} to update progress. OR + \li Run the function using QtConcurrent::run(). Write to a \l{Synchronizing + Threads}{thread-safe variable} to update progress. + \endlist + \row + \li One call + \li Perform an operation on all items of a container, using all available + cores. For example, producing thumbnails from a list of images. + \li Use Qt Concurrent's \l{QtConcurrent::}{filter()} function to select + container elements, and the \l{QtConcurrent::}{map()} function to apply + an operation to each element. To fold the output into a single result, + use \l{QtConcurrent::}{filterReduced()} and \l{QtConcurrent::}{mapReduced()} + instead. + \row + \li Permanent + \li Have an object living in another thread that can perform different + tasks upon request and/or can receive new data to work with. + \li Subclass a QObject to create a worker. Instantiate this worker object + and a QThread. Move the worker to the new thread. Send commands or + data to the worker object over queued signal-slot connections. + \row + \li Permanent + \li Repeatedly perform an expensive operation in another thread, where the + thread does not need to receive any signals or events. + \li Write the infinite loop directly within a reimplementation of QThread::run(). + Start the thread without an event loop. Let the thread emit signals to + send data back to the GUI thread. + \endtable */ /*! |