pthread_cond_init - Initializes a condition variable.
DECthreads POSIX 1003.1c Library (libpthread.so)
const pthread_condattr_t *attr);
Interfaces documented on this reference page conform to industry standards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
Condition variable to be initialized. Condition variable attributes object that defines the characteristics of the condition variable to be initialized.
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).
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 system-imposed 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.
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