Manual Pages for UNIX Operating System command usage for man pthread_rwlock_trywrlock

Standard C Library Functions            pthread_rwlock_wrlock(3C)



NAME
     pthread_rwlock_wrlock, pthread_rwlock_trywrlock  -  lock  or
     attempt to lock read-write lock object for writing

SYNOPSIS
     cc -mt [ flag... ] file... -lpthread [ library... ]
     #include 

     int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock);


     int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock);


DESCRIPTION
     The pthread_rwlock_wrlock() function applies a write lock to
     the read-write lock referenced by rwlock. The calling thread
     acquires the write  lock  if  no  other  thread  (reader  or
     writer)  holds  the  read-write  lock rwlock. Otherwise, the
     thread blocks until it can acquire the lock.


     The pthread_rwlock_trywrlock() function applies a write lock
     like  the  pthread_rwlock_wrlock() function, with the excep-
     tion that the function fails if any thread  currently  holds
     rwlock (for reading or writing).


     Writers are favored over readers of  the  same  priority  to
     avoid writer starvation. See pthread_rwlock_rdlock(3C).


     Results are undefined if any of these functions  are  called
     with an uninitialized read-write lock.


     If a signal is delivered to a thread  waiting  for  a  read-
     write  lock for writing, upon return from the signal handler
     the thread resumes waiting for the read-write lock for writ-
     ing as if it was not interrupted.

RETURN VALUES
     If successful, the pthread_rwlock_wrlock() function  returns
     0.  Otherwise,  an  error number is returned to indicate the
     error.


     The pthread_rwlock_trywrlock() function  returns  0  if  the
     lock for writing on the read-write lock object referenced by
     rwlock is acquired.  Otherwise an error number  is  returned
     to indicate the error.




SunOS 5.11          Last change: 23 Mar 2005                    1






Standard C Library Functions            pthread_rwlock_wrlock(3C)



ERRORS
     The pthread_rwlock_wrlock() function will fail if:

     EDEADLK    The current thread already  owns  the  read-write
                lock for writing or reading.



     The pthread_rwlock_trywrlock() function will fail if:

     EBUSY    The read-write lock could not be acquired for writ-
              ing  because  it  was already locked for reading or
              writing.


ATTRIBUTES
     See  attributes(5) for descriptions of the following  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


SEE ALSO
     pthread_rwlock_init(3C),          pthread_rwlock_unlock(3C),
     pthread_rwlockattr_init(3C),      pthread_rwlock_rdlock(3C),
     attributes(5), standards(5)



















SunOS 5.11          Last change: 23 Mar 2005                    2