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pthread_cond_init - Initializes a condition variable
const pthread_condattr_t *attr );
DECthreads POSIX 1003.1c Library (libpthread.so)
Interfaces documented on this reference page conform to industry standards
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
Condition variables are not owned by a particular thread. Any associated
storage is not automatically deallocated when the creating thread
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
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
0 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
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
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