Qt TaskTree

Qt TaskTree provides a declarative way to compose and execute asynchronous task workflows with proper error handling and execution policies.

Getting started

Qt TaskTree allows you to create complex task hierarchies with different execution policies, parallel/sequential execution, and proper error handling.

Key concepts:

• Recipes - Declarative descriptions of task workflows.
• Groups - Containers that define execution policies for child tasks.
• Storage - Thread-local storage system for sharing data between tasks.
• Iterators - Support for loops and repetitive task execution.

Using the Module

Using a Qt module's C++ API requires linking against the module library, either directly or through other dependencies. Several build tools have dedicated support for this, including CMake and qmake.

Building with CMake

Use the find_package() command to locate the needed module component in the Qt6 package:

find_package(Qt6 REQUIRED COMPONENTS TaskTree)
target_link_libraries(mytarget PRIVATE Qt6::TaskTree)

For more details, see the Build with CMake overview.

Building with qmake

To configure the module for building with qmake, add the module as a value of the QT variable in the project's .pro file:

QT += tasktree

Task adapters

The module includes several built-in task adapters for common operations:

• QProcessTask - Execute external processes.
• QConcurrentCallTask - Run functions via QtConcurrent.
• QNetworkReplyWrapperTask - Network operations.
• QTcpSocketWrapperTask - TCP socket operations.
• QBarrierTask - Synchronization primitives.
• QTimeoutTask - Timer-based delays.

Workflow Policies

Groups support different workflow policies for handling task results:

• StopOnError - Stop execution on first error (default).
• ContinueOnError - Continue execution despite errors.
• StopOnSuccess - Stop on first successful task.
• ContinueOnSuccess - Continue despite successful tasks.
• StopOnSuccessOrError - Stop on first completed task.
• FinishAllAndSuccess - Run all tasks, report success.
• FinishAllAndError - Run all tasks, report error.

Licenses

The Qt TaskTree module is available under commercial licenses from The Qt Company. In addition, it is available under free software licenses: The GNU Lesser General Public License, version 3, or the GNU General Public License, version 2. See Qt Licensing for further details.