Semaphore¶
A synchronization semaphore.
Description¶
A synchronization semaphore which can be used to synchronize multiple Threads. Initialized to zero on creation. Be careful to avoid deadlocks. For a binary version, see Mutex.
Warning:
To guarantee that the operating system is able to perform proper cleanup (no crashes, no deadlocks), these conditions must be met:
By the time a Semaphore's reference count reaches zero and therefore it is destroyed, no threads must be waiting on it.
By the time a Thread's reference count reaches zero and therefore it is destroyed, it must not be waiting on any semaphore.
Tutorials¶
Methods¶
post ( ) |
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try_wait ( ) |
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wait ( ) |
Method Descriptions¶
Error post ( )
Lowers the Semaphore, allowing one more thread in.
Note: This method internals' can't possibly fail, but an error code is returned for backwards compatibility, which will always be @GlobalScope.OK.
Error try_wait ( )
Like wait, but won't block, so if the value is zero, fails immediately and returns @GlobalScope.ERR_BUSY. If non-zero, it returns @GlobalScope.OK to report success.
Error wait ( )
Waits for the Semaphore, if its value is zero, blocks until non-zero.
Note: This method internals' can't possibly fail, but an error code is returned for backwards compatibility, which will always be @GlobalScope.OK.