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| author | Rich Felker <dalias@aerifal.cx> | 2011-04-06 12:24:34 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2011-04-06 12:24:34 -0400 |
| commit | a113434cd68ce30642c4995b1caadcd084be6f09 (patch) | |
| tree | b26daaeda2c9e2caf1605615c497a4a84191e01d /src/thread/sem_trywait.c | |
| parent | cd3bb38412cfcc3bc47985ba25287e0af463609a (diff) | |
| download | musl-a113434cd68ce30642c4995b1caadcd084be6f09.tar.gz musl-a113434cd68ce30642c4995b1caadcd084be6f09.tar.xz musl-a113434cd68ce30642c4995b1caadcd084be6f09.zip | |
major semaphore improvements (performance and correctness)
1. make sem_[timed]wait interruptible by signals, per POSIX 2. keep a waiter count in order to avoid unnecessary futex wake syscalls
Diffstat (limited to 'src/thread/sem_trywait.c')
| -rw-r--r-- | src/thread/sem_trywait.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/src/thread/sem_trywait.c b/src/thread/sem_trywait.c index c5370c70..beb7aa5d 100644 --- a/src/thread/sem_trywait.c +++ b/src/thread/sem_trywait.c @@ -3,9 +3,8 @@ int sem_trywait(sem_t *sem) { - int val = a_fetch_add(sem->__val, -1); - if (val > 0) return 0; - if (!a_fetch_add(sem->__val, 1)) + if (a_fetch_add(sem->__val, -1) > 0) return 0; + if (!a_fetch_add(sem->__val, 1) && sem->__val[1]) __wake(sem->__val, 1, 0); errno = EAGAIN; return -1; |