godot/doc/classes/Semaphore.xml

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<?xml version="1.0" encoding="UTF-8" ?>
<class name="Semaphore" inherits="RefCounted" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
<brief_description>
A synchronization mechanism used to control access to a shared resource by [Thread]s.
</brief_description>
<description>
A synchronization semaphore that can be used to synchronize multiple [Thread]s. Initialized to zero on creation. For a binary version, see [Mutex].
[b]Warning:[/b] Semaphores must be used carefully to avoid deadlocks.
[b]Warning:[/b] 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 [Thread]'s reference count reaches zero and it is therefore destroyed, it must not be waiting on any semaphore.
</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="post">
<return type="void" />
<description>
Lowers the [Semaphore], allowing one more thread in.
</description>
</method>
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<method name="try_wait">
<return type="bool" />
<description>
Like [method wait], but won't block, so if the value is zero, fails immediately and returns [code]false[/code]. If non-zero, it returns [code]true[/code] to report success.
</description>
</method>
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<method name="wait">
<return type="void" />
<description>
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Waits for the [Semaphore], if its value is zero, blocks until non-zero.
</description>
</method>
</methods>
</class>