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Diffstat (limited to 'doc/classes/WorkerThreadPool.xml')
| -rw-r--r-- | doc/classes/WorkerThreadPool.xml | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/doc/classes/WorkerThreadPool.xml b/doc/classes/WorkerThreadPool.xml index fced54ae7f..887dfbdcc0 100644 --- a/doc/classes/WorkerThreadPool.xml +++ b/doc/classes/WorkerThreadPool.xml @@ -1,10 +1,50 @@ <?xml version="1.0" encoding="UTF-8" ?> <class name="WorkerThreadPool" inherits="Object" version="4.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd"> <brief_description> + A singleton that allocates some [Thread]s on startup, used to offload tasks to these threads. </brief_description> <description> + The [WorkerThreadPool] singleton allocates a set of [Thread]s (called worker threads) on project startup and provides methods for offloading tasks to them. This can be used for simple multithreading without having to create [Thread]s. + Tasks hold the [Callable] to be run by the threads. [WorkerThreadPool] can be used to create regular tasks, which will be taken by one worker thread, or group tasks, which can be distributed between multiple worker threads. Group tasks execute the [Callable] multiple times, which makes them useful for iterating over a lot of elements, such as the enemies in an arena. + Here's a sample on how to offload an expensive function to worker threads: + [codeblocks] + [gdscript] + var enemies = [] # An array to be filled with enemies. + + func process_enemy_ai(enemy_index): + var processed_enemy = enemies[enemy_index] + # Expensive logic... + + func _process(delta): + var task_id = WorkerThreadPool.add_group_task(process_enemy_ai, enemies.size()) + # Other code... + WorkerThreadPool.wait_for_group_task_completion(task_id) + # Other code that depends on the enemy AI already being processed. + [/gdscript] + [csharp] + private List<Node> _enemies = new List<Node>(); // A list to be filled with enemies. + + private void ProcessEnemyAI(int enemyIndex) + { + Node processedEnemy = _enemies[enemyIndex]; + // Expensive logic here. + } + + public override void _Process(double delta) + { + long taskId = WorkerThreadPool.AddGroupTask(Callable.From<int>(ProcessEnemyAI), _enemies.Count); + // Other code... + WorkerThreadPool.WaitForGroupTaskCompletion(taskId); + // Other code that depends on the enemy AI already being processed. + } + [/csharp] + [/codeblocks] + The above code relies on the number of elements in the [code]enemies[/code] array remaining constant during the multithreaded part. + [b]Note:[/b] Using this singleton could affect performance negatively if the task being distributed between threads is not computationally expensive. </description> <tutorials> + <link title="Using multiple threads">$DOCS_URL/tutorials/performance/using_multiple_threads.html</link> + <link title="Thread-safe APIs">$DOCS_URL/tutorials/performance/thread_safe_apis.html</link> </tutorials> <methods> <method name="add_group_task"> @@ -15,6 +55,9 @@ <param index="3" name="high_priority" type="bool" default="false" /> <param index="4" name="description" type="String" default="""" /> <description> + Adds [param action] as a group task to be executed by the worker threads. The [Callable] will be called a number of times based on [param elements], with the first thread calling it with the value [code]0[/code] as a parameter, and each consecutive execution incrementing this value by 1 until it reaches [code]element - 1[/code]. + The number of threads the task is distributed to is defined by [param tasks_needed], where the default value [code]-1[/code] means it is distributed to all worker threads. [param high_priority] determines if the task has a high priority or a low priority (default). You can optionally provide a [param description] to help with debugging. + Returns a group task ID that can be used by other methods. </description> </method> <method name="add_task"> @@ -23,36 +66,44 @@ <param index="1" name="high_priority" type="bool" default="false" /> <param index="2" name="description" type="String" default="""" /> <description> + Adds [param action] as a task to be executed by a worker thread. [param high_priority] determines if the task has a high priority or a low priority (default). You can optionally provide a [param description] to help with debugging. + Returns a task ID that can be used by other methods. </description> </method> <method name="get_group_processed_element_count" qualifiers="const"> <return type="int" /> <param index="0" name="group_id" type="int" /> <description> + Returns how many times the [Callable] of the group task with the given ID has already been executed by the worker threads. + [b]Note:[/b] If a thread has started executing the [Callable] but is yet to finish, it won't be counted. </description> </method> <method name="is_group_task_completed" qualifiers="const"> <return type="bool" /> <param index="0" name="group_id" type="int" /> <description> + Returns [code]true[/code] if the group task with the given ID is completed. </description> </method> <method name="is_task_completed" qualifiers="const"> <return type="bool" /> <param index="0" name="task_id" type="int" /> <description> + Returns [code]true[/code] if the task with the given ID is completed. </description> </method> <method name="wait_for_group_task_completion"> <return type="void" /> <param index="0" name="group_id" type="int" /> <description> + Pauses the thread that calls this method until the group task with the given ID is completed. </description> </method> <method name="wait_for_task_completion"> <return type="void" /> <param index="0" name="task_id" type="int" /> <description> + Pauses the thread that calls this method until the task with the given ID is completed. </description> </method> </methods> |