DosCloseEventSem: Difference between revisions

Revision as of 16:56, 16 May 2016

Syntax

rc = DosCloseEventSem( hevSemaphore );

Parameters

 HEV hevSemaphore (input)

This is a handle to the event semaphore (HEV) to be closed.

Returns

 APIRET rc

The following values can be returned

0	NO_ERROR	Semaphore closed successfully
6	ERROR_INVALID_HANDLE	Error, The value in hevSemaphore does not point to a valid semaphore
301	ERROR_SEM_BUSY	Error, Another thread in this process is blocked on the semaphore

Include Info

#define INCL_DOSSEMAPHORES
#include <os2.h>

Usage Explanation

DosCloseEventSem decrements, by one (1), the usage count for the semaphore specified by the handle hevSemaphore. If the usage count goes to zero (0) then the semaphore is freed from the system.

The usage count for private semaphores is always one (1) so all private semaphores will be freed on successful completion of this call.
Shared (named or unnamed) semaphores may have usage counts greater than one (1), therefore they may or may not be freed from system resources on successful completion of DosCloseEventSem.

Relevant Structures

Gotchas

Sample Code

#define INCL_DOSSEMAPHORES
#include 

HEV hevMySemaphore; /* pointer to my semaphore handle */

	/* an event semaphore is successfully created */
	/* its handle is placed in hevMySemaphore  */

	rc = DosCloseEventSem(hevMySemaphore);

	if (rc != 0)
	{
	  /* We got an error to take care of. */
	}
	else
	{
	  /* The semaphore was successfully closed */
	}

@@ Line 46: / Line 46: @@
 === Sample Code ===
+<PRE>
 #define INCL_DOSSEMAPHORES
 #include
@@ Line 65: / Line 65: @@
 	  /* The semaphore was successfully closed */
 	}
+</PRE>
 === See Also ===
 [[OS2 API:CPI:DosCreateEventSem|CPI:DosCreateEventSem]], [[OS2 API:CPI:DosOpenEventSem|CPI:DosOpenEventSem]], [[OS2 API:CPI:DosPostEventSem|CPI:DosPostEventSem]], [[OS2 API:CPI:DosQueryEventSem|CPI:DosQueryEventSem]], [[OS2 API:CPI:DosResetEventSem|CPI:DosResetEventSem]],  [[OS2 API:CPI:DosWaitEventSem|CPI:DosWaitEventSem]]
 [[Category:The OS2 API Project]]