1pthread_rwlock_unlock(3C)Standard C Library Functionspthread_rwlock_unlock(3C)
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NAME

6       pthread_rwlock_unlock - unlock read-write lock object
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SYNOPSIS

9       cc -mt [ flag... ] file... -lpthread [ library... ]
10       #include <pthread.h>
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12       int pthread_rwlock_unlock(pthread_rwlock_t *rwlock);
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DESCRIPTION

16       The  pthread_rwlock_unlock()  function is called to release a lock held
17       on the read-write lock object referenced by rwlock. Results  are  unde‐
18       fined if the read-write lock rwlock is not held by the calling thread.
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21       If  this  function is called to release a read lock from the read-write
22       lock object and there are other read locks currently held on this read-
23       write  lock  object,  the  read-write  lock  object remains in the read
24       locked state. If this function releases the calling thread's last  read
25       lock  on  this  read-write  lock  object, then the calling thread is no
26       longer one of the owners of the object. If this function  releases  the
27       last  read  lock  for  this read-write lock object, the read-write lock
28       object will be put in the unlocked state with no owners.
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31       If this function is called to release a write lock for this  read-write
32       lock  object,  the  read-write  lock object will be put in the unlocked
33       state with no owners.
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36       If the call to the  pthread_rwlock_unlock()  function  results  in  the
37       read-write lock object becoming unlocked and there are multiple threads
38       waiting to acquire the read-write lock object for writing, the schedul‐
39       ing  policy  is  used to determine which thread acquires the read-write
40       lock object for writing. If  there  are  multiple  threads  waiting  to
41       acquire  the  read-write lock object for reading, the scheduling policy
42       is used to determine the order in which the waiting threads acquire the
43       read-write  lock  object  for  reading.   If there are multiple threads
44       blocked on rwlock for both read locks and write locks, it  is  unspeci‐
45       fied  whether  the  readers  acquire the lock first or whether a writer
46       acquires the lock first.
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49       Results are undefined if any of these  functions  are  called  with  an
50       uninitialized read-write lock.
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RETURN VALUES

53       If  successful,  the pthread_rwlock_unlock() function returns 0. Other‐
54       wise, an error number is returned to indicate the error.
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ATTRIBUTES

57       See attributes(5) for descriptions of the following attributes:
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62       ┌─────────────────────────────┬─────────────────────────────┐
63       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
64       ├─────────────────────────────┼─────────────────────────────┤
65       │Interface Stability          │Standard                     │
66       ├─────────────────────────────┼─────────────────────────────┤
67       │MT-Level                     │MT-Safe                      │
68       └─────────────────────────────┴─────────────────────────────┘
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SEE ALSO

71       pthread_rwlock_init(3C),                     pthread_rwlock_rdlock(3C),
72       pthread_rwlock_wrlock(3C),  pthread_rwlockattr_init(3C), attributes(5),
73       standards(5)
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77SunOS 5.11                        23 Mar 2005        pthread_rwlock_unlock(3C)