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Standard C Library Functions              pthread_rwlock_init(3C)



NAME
     pthread_rwlock_init, pthread_rwlock_destroy - initialize  or
     destroy read-write lock object

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

     int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock,
          const pthread_rwlockattr_t *restrict attr);


     int pthread_rwlock_destroy(pthread_rwlock_t **rwlock);


     pthread_rwlock_t rwlock=PTHREAD_RWLOCK_INITIALIZER;


DESCRIPTION
     The pthread_rwlock_init()  function  initializes  the  read-
     write  lock referenced by rwlock with  the attributes refer-
     enced by attr.  If attr is  NULL,  the  default   read-write
     lock attributes are used; the effect is the same as  passing
     the address of a default read-write lock attributes  object.
     Once  initialized, the lock can be used any  number of times
     without being re-initialized.  Upon  successful  initializa-
     tion,  the state of the read-write lock  becomes initialized
     and     unlocked.      Results     are     undefined      if
     pthread_rwlock_init()  is  called specifying an already ini-
     tialized read-write lock.  Results are undefined if a  read-
     write lock is used without first being  initialized.


     If the  pthread_rwlock_init() function fails, rwlock is  not
     initialized and the contents of  rwlock are undefined.


     The pthread_rwlock_destroy()  function  destroys  the  read-
     write  lock  object  referenced  by rwlock and  releases any
     resources used by the lock.  The effect of subsequent use of
     the  lock  is undefined until the lock  is re-initialized by
     another call to pthread_rwlock_init(). An implementation may
     cause  pthread_rwlock_destroy() to set the object referenced
     by rwlock to an invalid value.   Results  are  undefined  if
     pthread_rwlock_destroy()  is  called  when  any thread holds
     rwlock.  Attempting to destroy an uninitialized   read-write
     lock results in undefined behaviour.  A destroyed read-write
     lock     object     can     be     re-initialized      using
     pthread_rwlock_init();  the results of otherwise referencing
     the read-write lock object after it  has been destroyed  are
     undefined.




SunOS 5.11          Last change: 23 mar 2005                    1






Standard C Library Functions              pthread_rwlock_init(3C)



     In  cases  where  default  read-write  lock  attributes  are
     appropriate,  the  macro   PTHREAD_RWLOCK_INITIALIZER can be
     used to initialize  read-write  locks  that  are  statically
     allocated.   The effect is equivalent to dynamic initializa-
     tion by a call to  pthread_rwlock_init() with the  parameter
     attr  specified  as  NULL,  except that no error  checks are
     performed.

RETURN VALUES
     If    successful,     the      pthread_rwlock_init()     and
     pthread_rwlock_destroy()  functions return  0. Otherwise, an
     error number is returned to indicate the error.

ERRORS
     The  pthread_rwlock_init()   and    pthread_rwlock_destroy()
     functions will fail if:

     EINVAL    The value specified by attr is invalid.


     EINVAL    The value specified by rwlock is invalid.


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_rdlock(3C),        pthread_rwlock_unlock(3C),
     pthread_rwlock_wrlock(3C),      pthread_rwlockattr_init(3C),
     attributes(5), standards(5)











SunOS 5.11          Last change: 23 mar 2005                    2