suds_lockstate(S)

suds_lockstate -- return the status of a spin lock

Syntax

cc . . . -lsuds

#include <sys/semaphore.h>

int suds_lockstate(struct suds_lock *lock_addr);

Description

The suds_lockstate function is used to obtain the status of a lock at one particular instant in time. The value returned only indicates that at the time of reading the lock, the lock was in one particular state. There is no guarantee that the lock is still in this state. This function is primarily intended for debugging purposes and for allowing ASSERT statements to be included within an application.

Return values

Upon successful completion, the function returns SUDS_LOCK_LOCKED to indicate that the lock was held by a process, SUDS_LOCK_UNLOCKED to indicate that the lock was not held. Otherwise -1 is returned and errno is set accordingly.

Diagnostics

[EINVAL]: The specified address of the lock is not a valid lock address.

Examples

The following code shows an application using the suds_state function to ensure that a particular lock is held when a function is called. Although there is no guarantee that the process executing the function is the owner of the lock, this ASSERT does help to ensure that the lock required by the function is correctly obtained.

   function_name
   {
      ASSERT(suds_lockstate(&lock_name) == SUDS_LOCK_LOCKED);
   .
   .
   .
   }

Standards conformance

suds_state is not part of any currently supported standard; it is an extension of AT&T System V provided by The Santa Cruz Operation, Inc.