NAME    [Toc]    [Back]

       pthread_cond_init - Initializes a condition variable

SYNOPSIS    [Toc]    [Back]

       #include <pthread.h>

       int pthread_cond_init(
               pthread_cond_t *cond,
               const pthread_condattr_t *attr );

LIBRARY    [Toc]    [Back]

       DECthreads POSIX 1003.1c Library (libpthread.so)

STANDARDS    [Toc]    [Back]

       Interfaces  documented  on  this reference page conform to
       industry standards as follows:

       IEEE Std 1003.1c-1995, POSIX  System  Application  Program
       Interface

PARAMETERS    [Toc]    [Back]

       Condition  variable to be initialized.  Condition variable
       attributes object that defines the characteristics of  the
       condition variable to be initialized.

DESCRIPTION    [Toc]    [Back]

       This  routine  initializes  the  condition variable (cond)
       with attributes referenced by attr. If attr is  NULL,  the
       default condition variable attributes are used.

       A  condition  variable is a synchronization object used in
       conjunction with a mutex. A mutex controls access to  data
       that  is shared among threads; a condition variable allows
       threads to wait for that data to enter a defined state.

       Condition variables are not owned by a particular  thread.
       Any  associated  storage  is not automatically deallocated
       when the creating thread terminates.

       Use the DECthreads macro PTHREAD_COND_INITIALIZER to  initialize
  statically  allocated  condition variables to the
       default  condition  variable  attributes.   To  call  this
       macro, enter:

       pthread_cond_t condition= PTHREAD_COND_INITIALIZER

       When  statically  initialized, a condition variable should
       not also be using pthread_cond_init(3). Also, a statically
       initialized condition variable need not be destroyed using
       pthread_cond_destroy(3).

       Under certain circumstances, it  might  be  impossible  to
       wait upon a statically initialized condition variable when
       the process virtual address space (or  some  other  memory
       limit)    is   nearly   exhausted.   In   such   a   case,
       pthread_cond_wait(3)  or   pthread_cond_timedwait(3)   can
       return  [ENOMEM].  To  avoid  this possibility, initialize
       critical condition variables using pthread_cond_init(3).

RETURN VALUES    [Toc]    [Back]

       If an error condition  occurs,  this  routine  returns  an
       integer  value indicating the type of error, the condition
       variable is not initialized, and the contents of cond  are
       undefined. Possible return values are as follows: Successful
 completion.  The system lacks the necessary  resources
       to  initialize  another condition variable, or The systemimposed
 limit on the total number of  condition  variables
       under  execution by a single user is exceeded.  The implementation
 has detected  an  attempt  to  reinitialize  the
       object  referenced  by cond, a previously initialized, but
       not yet destroyed condition variable.  The value specified
       by  attr  is  invalid.  Insufficient memory exists to initialize
 the condition variable.

ERRORS    [Toc]    [Back]

       None

SEE ALSO    [Toc]    [Back]

       Functions:                      pthread_cond_broadcast(3),
       pthread_cond_destroy(3),           pthread_cond_signal(3),
       pthread_cond_timedwait(3), pthread_cond_wait(3)

       Manuals: Guide to DECthreads and Programmer's Guide



                                             pthread_cond_init(3)