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.. DO NOT EDIT THIS FILE, but the Semaphore.xml source instead.
.. The source is found in doc/classes or modules/<name>/doc_classes.

.. _class_Semaphore:

Semaphore
=========

**Inherits:** :ref:`Reference<class_Reference>` **<** :ref:`Object<class_Object>`

A synchronization semaphore.

Description
-----------

A synchronization semaphore which can be used to synchronize multiple :ref:`Thread<class_Thread>`\ s. Initialized to zero on creation. Be careful to avoid deadlocks. For a binary version, see :ref:`Mutex<class_Mutex>`.

Tutorials
---------

- :doc:`../tutorials/performance/using_multiple_threads`

Methods
-------

+---------------------------------------+--------------------------------------------------------------+
| void                                  | :ref:`post<class_Semaphore_method_post>` **(** **)**         |
+---------------------------------------+--------------------------------------------------------------+
| :ref:`Error<enum_@GlobalScope_Error>` | :ref:`try_wait<class_Semaphore_method_try_wait>` **(** **)** |
+---------------------------------------+--------------------------------------------------------------+
| void                                  | :ref:`wait<class_Semaphore_method_wait>` **(** **)**         |
+---------------------------------------+--------------------------------------------------------------+

Method Descriptions
-------------------

.. _class_Semaphore_method_post:

- void **post** **(** **)**

Lowers the ``Semaphore``, allowing one more thread in.

----

.. _class_Semaphore_method_try_wait:

- :ref:`Error<enum_@GlobalScope_Error>` **try_wait** **(** **)**

Like :ref:`wait<class_Semaphore_method_wait>`, but won't block, so if the value is zero, fails immediately and returns :ref:`@GlobalScope.ERR_BUSY<class_@GlobalScope_constant_ERR_BUSY>`. If non-zero, it returns :ref:`@GlobalScope.OK<class_@GlobalScope_constant_OK>` to report success.

----

.. _class_Semaphore_method_wait:

- void **wait** **(** **)**

Waits for the ``Semaphore``, if its value is zero, blocks until non-zero.