Semaphore ​
Inherits: RefCounted < Object
A synchronization mechanism used to control access to a shared resource by Threads.
Description
A synchronization semaphore that can be used to synchronize multiple Threads. Initialized to zero on creation. For a binary version, see 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 Thread's reference count reaches zero and it is therefore destroyed, it must not be waiting on any semaphore.
Tutorials
Methods
void | post() |
try_wait() | |
void | wait() |
Method Descriptions
void post() 🔗
Lowers the Semaphore, allowing one more thread in.
Like 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.
void wait() 🔗
Waits for the Semaphore, if its value is zero, blocks until non-zero.