Threads in other processes can open a handle to an existing semaphore object by specifying its name in a call to the OpenSemaphore function. The creating thread can also specify a name for the semaphore object. The initial count must be neither less than zero nor greater than the maximum value. The creating thread specifies the initial count and the maximum value of the count for the object. When the count is zero-indicating that the window limit has been reached-the wait function blocks execution of the window-creation code.Ī thread uses the CreateSemaphore or CreateSemaphoreEx function to create a semaphore object. The application specifies the semaphore object in call to one of the wait functions before each window is created. It uses a semaphore with a maximum count equal to the window limit, decrementing the count whenever a window is created and incrementing it whenever a window is closed.
Rail maze 2 semaphore level windows#
For example, an application might place a limit on the number of windows that it creates. It acts as a gate that limits the number of threads sharing the resource to a specified maximum number. The semaphore object is useful in controlling a shared resource that can support a limited number of users. The state of a semaphore is set to signaled when its count is greater than zero, and nonsignaled when its count is zero. When the count reaches zero, no more threads can successfully wait for the semaphore object state to become signaled. The count is decremented each time a thread completes a wait for the semaphore object and incremented each time a thread releases the semaphore. A semaphore object is a synchronization object that maintains a count between zero and a specified maximum value.
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