The semaphore is the simplest thread synchronization primitive, consisting of a simple counter. More...
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Data Structures | |
| struct | vlc_sem_t |
| Semaphore. More... | |
Functions | |
| void | vlc_sem_init (vlc_sem_t *, unsigned count) |
| Initializes a semaphore. More... | |
| int | vlc_sem_post (vlc_sem_t *) |
| Increments the value of a semaphore. More... | |
| void | vlc_sem_wait (vlc_sem_t *) |
| Waits on a semaphore. More... | |
| int | vlc_sem_timedwait (vlc_sem_t *sem, vlc_tick_t deadline) |
| Waits on a semaphore within a deadline. More... | |
Detailed Description
The semaphore is the simplest thread synchronization primitive, consisting of a simple counter.
See also POSIX sem_t .
Function Documentation
◆ vlc_sem_init()
| void vlc_sem_init | ( | vlc_sem_t * | , |
| unsigned | count | ||
| ) |
Initializes a semaphore.
- Parameters
-
count initial semaphore value (typically 0)
References vlc_sem_t::value.
Referenced by vlc_getaddrinfo_i11e(), and vlc_mta_acquire().
◆ vlc_sem_post()
| int vlc_sem_post | ( | vlc_sem_t * | ) |
Increments the value of a semaphore.
- Note
- This function is not a cancellation point.
- Returns
- 0 on success, EOVERFLOW in case of integer overflow.
References unlikely, vlc_sem_t::value, and vlc_atomic_notify_one().
Referenced by MtaMainLoop(), vlc_gai_thread(), vlc_getaddrinfo_notify(), vlc_interrupt_sem(), and vlc_mta_release().
◆ vlc_sem_timedwait()
| int vlc_sem_timedwait | ( | vlc_sem_t * | sem, |
| vlc_tick_t | deadline | ||
| ) |
Waits on a semaphore within a deadline.
This function waits for the semaphore just like vlc_sem_wait(), but only up to a given deadline.
- Parameters
-
sem semaphore to wait for deadline deadline to wait until
- Return values
-
0 the semaphore was decremented ETIMEDOUT the deadline was reached
References likely, vlc_sem_t::value, and vlc_atomic_timedwait().
◆ vlc_sem_wait()
| void vlc_sem_wait | ( | vlc_sem_t * | ) |
Waits on a semaphore.
This function atomically waits for the semaphore to become non-zero then decrements it, and returns. If the semaphore is non-zero on entry, it is immediately decremented.
- Note
- This function may be a point of cancellation.
References likely, vlc_sem_t::value, and vlc_atomic_wait().
Referenced by MtaMainLoop(), vlc_getaddrinfo_i11e(), vlc_mta_acquire(), and vlc_sem_wait_i11e().
