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- :github_url: hide
- .. DO NOT EDIT THIS FILE!!!
- .. Generated automatically from Godot engine sources.
- .. Generator: https://github.com/godotengine/godot/tree/master/doc/tools/make_rst.py.
- .. XML source: https://github.com/godotengine/godot/tree/master/doc/classes/Semaphore.xml.
- .. _class_Semaphore:
- Semaphore
- =========
- **Inherits:** :ref:`RefCounted<class_RefCounted>` **<** :ref:`Object<class_Object>`
- A synchronization mechanism used to control access to a shared resource by :ref:`Thread<class_Thread>`\ s.
- .. rst-class:: classref-introduction-group
- Description
- -----------
- A synchronization semaphore that can be used to synchronize multiple :ref:`Thread<class_Thread>`\ s. Initialized to zero on creation. For a binary version, see :ref:`Mutex<class_Mutex>`.
- \ **Warning:** Semaphores must be used carefully to avoid deadlocks.
- \ **Warning:** To guarantee that the operating system is able to perform proper cleanup (no crashes, no deadlocks), these conditions must be met:
- - When a **Semaphore**'s reference count reaches zero and it is therefore destroyed, no threads must be waiting on it.
- - When a :ref:`Thread<class_Thread>`'s reference count reaches zero and it is therefore destroyed, it must not be waiting on any semaphore.
- .. rst-class:: classref-introduction-group
- Tutorials
- ---------
- - :doc:`Using multiple threads <../tutorials/performance/using_multiple_threads>`
- - :doc:`Thread-safe APIs <../tutorials/performance/thread_safe_apis>`
- .. rst-class:: classref-reftable-group
- Methods
- -------
- .. table::
- :widths: auto
- +-------------------------+-----------------------------------------------------------------------------------+
- | |void| | :ref:`post<class_Semaphore_method_post>`\ (\ count\: :ref:`int<class_int>` = 1\ ) |
- +-------------------------+-----------------------------------------------------------------------------------+
- | :ref:`bool<class_bool>` | :ref:`try_wait<class_Semaphore_method_try_wait>`\ (\ ) |
- +-------------------------+-----------------------------------------------------------------------------------+
- | |void| | :ref:`wait<class_Semaphore_method_wait>`\ (\ ) |
- +-------------------------+-----------------------------------------------------------------------------------+
- .. rst-class:: classref-section-separator
- ----
- .. rst-class:: classref-descriptions-group
- Method Descriptions
- -------------------
- .. _class_Semaphore_method_post:
- .. rst-class:: classref-method
- |void| **post**\ (\ count\: :ref:`int<class_int>` = 1\ ) :ref:`🔗<class_Semaphore_method_post>`
- Lowers the **Semaphore**, allowing one thread in, or more if ``count`` is specified.
- .. rst-class:: classref-item-separator
- ----
- .. _class_Semaphore_method_try_wait:
- .. rst-class:: classref-method
- :ref:`bool<class_bool>` **try_wait**\ (\ ) :ref:`🔗<class_Semaphore_method_try_wait>`
- Like :ref:`wait<class_Semaphore_method_wait>`, but won't block, so if the value is zero, fails immediately and returns ``false``. If non-zero, it returns ``true`` to report success.
- .. rst-class:: classref-item-separator
- ----
- .. _class_Semaphore_method_wait:
- .. rst-class:: classref-method
- |void| **wait**\ (\ ) :ref:`🔗<class_Semaphore_method_wait>`
- Waits for the **Semaphore**, if its value is zero, blocks until non-zero.
- .. |virtual| replace:: :abbr:`virtual (This method should typically be overridden by the user to have any effect.)`
- .. |const| replace:: :abbr:`const (This method has no side effects. It doesn't modify any of the instance's member variables.)`
- .. |vararg| replace:: :abbr:`vararg (This method accepts any number of arguments after the ones described here.)`
- .. |constructor| replace:: :abbr:`constructor (This method is used to construct a type.)`
- .. |static| replace:: :abbr:`static (This method doesn't need an instance to be called, so it can be called directly using the class name.)`
- .. |operator| replace:: :abbr:`operator (This method describes a valid operator to use with this type as left-hand operand.)`
- .. |bitfield| replace:: :abbr:`BitField (This value is an integer composed as a bitmask of the following flags.)`
- .. |void| replace:: :abbr:`void (No return value.)`
|
