pthread_cond_init

Creates a condition variable.

Syntax

pthread_cond_init( cond, attr );

Argument Data Type Access

cond opaque pthread_cond_t write attr opaque pthread_ read condattr_t

C Binding

int
pthread_cond_init (
pthread_cond_t *cond,
pthread_condattr_t attr);

Arguments

cond: Condition variable that is created.
attr: Condition variable attributes object that defines the characteristics of the condition variable created. If you specify pthread_condattr_default, default attributes are used.

Description

This routine creates and initializes a condition variable. A condition variable is a synchronization object used in conjunction with a mutex. A mutex controls access to shared data; 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.

Return Values

If an error condition occurs, this routine returns -1, the condition variable is not initialized, and the contents of cond are undefined. This routine sets errno to the corresponding error value. Possible return values are as follows:

Return Error Description

0 Successful completion. -1 [EAGAIN] The system lacks the necessary resources to initialize another condition variable. The system-imposed limit on the total number of condition variables under execution by a single user is exceeded. -1 [ENOMEM] Insufficient memory exists to initialize the condition variable.