DosCloseMutexSem: Difference between revisions
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=== Syntax === | === Syntax === | ||
rc = DosCloseMutexSem( ''phmtxSemaphore'' ); | |||
rc = DosCloseMutexSem( ''phmtxSemaphore'' ); | |||
=== Parameters === | === Parameters === | ||
PHMTX ''phmtxSemaphore'' (input) | |||
This is a pointer to the HMTX that contains the handle to the semaphore to be closed. | |||
This is a pointer to the HMTX that contains the handle to the semaphore to | |||
be closed. | |||
=== Returns === | === Returns === | ||
APIRET rc | |||
The following values can be returned | The following values can be returned | ||
{| border="1" | {| border="1" | ||
|- | |- | ||
| Line 27: | Line 22: | ||
|ERROR_SEM_BUSY | |ERROR_SEM_BUSY | ||
|Error, Another thread in this process is blocked on the semaphore | |Error, Another thread in this process is blocked on the semaphore | ||
|} | |} | ||
=== Usage Explanation === | === Usage Explanation === | ||
DosCloseMutexSem decrements, by one (1), the usage count for the semaphore pointed to by ''phmtxSemaphore''. If the usage count goes to zero (0) then the semaphore is freed from the system. | |||
DosCloseMutexSem decrements, by one (1), the usage count for the semaphore | |||
pointed to by ''phmtxSemaphore''. | |||
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. | * 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 DosCloseMutexSem. | * 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 DosCloseMutexSem. | ||
=== Sample Code === | === Sample Code === | ||
<PRE> | <PRE> | ||
#define INCL_DOSSEMAPHORES | #define INCL_DOSSEMAPHORES | ||
#include | #include <os2.h> | ||
PHMTX phmtxMySemaphore; /* pointer to my semaphore handle */ | PHMTX phmtxMySemaphore; /* pointer to my semaphore handle */ | ||
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</PRE> | </PRE> | ||
=== See Also === | === See Also === | ||
[[ | *[[DosCreateMutexSem]] | ||
*[[DosOpenMutexSem]] | |||
*[[DosQueryMutexSem]] | |||
*[[DosReleaseMutexSem]] | |||
*[[DosRequestMutexSem]] | |||
[[Category: | [[Category:Dos]] | ||
Revision as of 06:13, 9 January 2017
Syntax
rc = DosCloseMutexSem( phmtxSemaphore );
Parameters
PHMTX phmtxSemaphore (input)
This is a pointer to the HMTX that contains the handle to the semaphore 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 phmtxSemaphore does not point to a valid semaphore |
| 301 | ERROR_SEM_BUSY | Error, Another thread in this process is blocked on the semaphore |
Usage Explanation
DosCloseMutexSem decrements, by one (1), the usage count for the semaphore pointed to by phmtxSemaphore. 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 DosCloseMutexSem.
Sample Code
#define INCL_DOSSEMAPHORES
#include <os2.h>
PHMTX phmtxMySemaphore; /* pointer to my semaphore handle */
/* a mutex semaphore is successfully created */
/* its handle is placed in phmtxMySemaphore */
rc = DosCloseMutexSem(phmtxMySemaphore);
if (rc != 0)
{
/* We got an error to take care of. */
}
else
{
/* The semaphore was successfully closed */
}