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28 .Dt PTHREAD_RWLOCK_WRLOCK 3
31 .Nm pthread_rwlock_wrlock ,
32 .Nm pthread_rwlock_trywrlock
33 .Nd acquire a read/write lock for writing
35 .Fd #include <pthread.h>
37 .Fn pthread_rwlock_wrlock "pthread_rwlock_t *lock"
39 .Fn pthread_rwlock_trywrlock "pthread_rwlock_t *lock"
42 .Fn pthread_rwlock_wrlock
43 function blocks until a write lock can be acquired against
46 .Fn pthread_rwlock_trywrlock
47 function performs the same action, but does not block if the lock
48 cannot be immediately obtained.
50 The results are undefined if the calling thread already holds the
51 lock at the time the call is made.
52 .Sh IMPLEMENTATION NOTES
53 To prevent writer starvation, writers are favored over readers.
56 .Fn pthread_rwlock_wrlock
58 .Fn pthread_rwlock_trywrlock
59 functions will return zero. Otherwise an error number will be returned
60 to indicate the error.
62 .Xr pthread_rwlock_trywrlock 3 ,
63 .Xr pthread_rwlock_unlock 3 ,
64 .Xr pthread_rwlock_wrlock 3
67 .Fn pthread_rwlock_wrlock
69 .Fn pthread_rwlock_trywrlock
70 functions are expected to conform to
74 .Fn pthread_rwlock_trywrlock
75 function will fail if:
78 The calling thread is not able to acquire the lock without blocking.
82 .Fn pthread_rwlock_wrlock
84 .Fn pthread_rwlock_trywrlock
85 functions may fail if:
88 The calling thread already owns the read/write lock (for reading
91 The value specified by
95 Insufficient memory exists to initialize the lock (applies to
96 statically initialized locks only).
100 .Fn pthread_rwlock_wrlock
101 function first appeared in