Zachary Turner wrote:
2009/6/20 Ion Gaztañaga <igaztanaga@gmail.com>:
Zachary Turner wrote:
Sorry for jumping into the middle of this. But shouldn't it only notify_one() if count is greater than or equal to 0? Not unconditionally. It's possible to initialize the semaphore with a negative count, and in that case a call to wait() should not unblock until the semaphore is 0 or higher. Ummm... Interprocess models POSIX primitives and I see that
#include <semaphore.h>
int sem_init(sem_t *sem, int pshared, unsigned int value);
semaphore value should be always positive, something that does not happen in Interprocess:
interprocess_semaphore(int initialCount);
So I think I should change interprocess constructor to an unsigned int.
That works too :) Just out of curiosity why doesn't windows backend just use built-in windows api functions for manipulating semaphores? CreateSemaphore, etc? I haven't done any performance benchmarks myself, but it seems like using native system calls would be faster and more scalable.
Because that semaphore couldn't be placed in shared memory and memory-mapped files, like its POSIX equivalent with pshared set to true: int sem_init(sem_t *sem, int pshared, unsigned int value); http://www.opengroup.org/onlinepubs/007908775/xsh/sem_init.html Best, Ion