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pthread_cond_init(3)
NAME
  pthread_cond_init - Initializes a condition variable

SYNOPSIS
  #include <pthread.h>

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

LIBRARY
  DECthreads POSIX 1003.1c Library (libpthread.so)

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

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

PARAMETERS
  cond
      Condition variable to be initialized.

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

DESCRIPTION
  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
  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:

  0   Successful completion.

  [EAGAIN]
      The system lacks the necessary resources to initialize another
      condition variable, or The system-imposed limit on the total number of
      condition variables under execution by a single user is exceeded.

  [EBUSY]
      The implementation has detected an attempt to reinitialize the object
      referenced by cond, a previously initialized, but not yet destroyed
      condition variable.

  [EINVAL]
      The value specified by attr is invalid.

  [ENOMEM]
      Insufficient memory exists to initialize the condition variable.

ERRORS
  None

SEE ALSO
  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

Index for Section 3

Alphabetical listing for P

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