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