DosPurgeQueue
Purges a queue of all its elements.
Syntax
#define INCL_DOSQUEUES #include <os2.h> HQUEUE hq; /* The handle of the queue to be purged. */ APIRET ulrc; /* Return Code. */ ulrc = DosPurgeQueue(hq);
Parameters
- hq (HQUEUE) - input
- The handle of the queue to be purged.
Return Code
ulrc (APIRET) - returns
DosPurgeQueue returns one of the following values:
- 0 NO_ERROR
- 330 ERROR_QUE_PROC_NOT_OWNED
- 337 ERROR_QUE_INVALID_HANDLE
Remarks
The server process issues DosPurgeQueue to empty a queue of all its elements. This function is not available to client processes.
Warning: This is an unconditional purge of all elements in the queue.
Example Code
This example creates a queue, writes to it, queries it, purges it, and finally closes it.
#define INCL_DOSQUEUES /* DOS Queue values */
#define INCL_DOSERRORS /* DOS Error values */
#include <os2.h>
#include <stdio.h>
#include <string.h>
#define QUE_NAME "\\QUEUES\\PANDAWRITE\\LOCALQUEUE"
int main(VOID) {
HQUEUE QueueHandle = NULLHANDLE; /* Queue handle */
CHAR *DataBuffer = ""; /* Data to write to queue */
ULONG ulNumElems = 0L; /* Number of elements on queue */
APIRET rc = NO_ERROR; /* Return code */
rc = DosCreateQueue(&QueueHandle, /* Queue handle */
QUE_LIFO | /* Last In, First Out ordering */
QUE_CONVERT_ADDRESS, /* Do 16-bit to 32-bit conversion */
QUE_NAME); /* Name of the queue */
if (rc!= NO_ERROR) {
printf ("DosCreateQueue error: return code = %u\n", rc);
return 1;
}
DataBuffer = "Element 1 of 2";
rc = DosWriteQueue (QueueHandle, 100L, strlen(DataBuffer),
(PVOID)DataBuffer, 0L);
if (rc!= NO_ERROR) {
printf ("DosWriteQueue error: return code = %u\n", rc);
return 1;
}
rc = DosQueryQueue (QueueHandle, &ulNumElems);
if (rc != NO_ERROR) {
printf ("DosQueryQueue error: return code = %u\n", rc);
return 1;
} else { printf ("DosQueryQueue: %u elements\n", ulNumElems); }
DataBuffer = "Element 2 of 2";
rc = DosWriteQueue (QueueHandle, 200L, strlen(DataBuffer),
(PVOID)DataBuffer, 0L);
if (rc!= NO_ERROR) {
printf ("DosWriteQueue error: return code = %u\n", rc);
return 1;
}
rc = DosQueryQueue (QueueHandle, &ulNumElems);
if (rc != NO_ERROR) {
printf ("DosQueryQueue error: return code = %u\n", rc);
return 1;
} else { printf ("DosQueryQueue: %u elements\n", ulNumElems); }
rc = DosPurgeQueue (QueueHandle);
if (rc != NO_ERROR) {
printf ("DosPurgeQueue error: return code = %u\n", rc);
return 1; }
rc = DosQueryQueue (QueueHandle, &ulNumElems);
if (rc != NO_ERROR) {
printf ("DosQueryQueue error: return code = %u\n", rc);
return 1;
} else { printf ("DosQueryQueue: %u elements\n", ulNumElems); }
rc = DosCloseQueue(QueueHandle); /* Close the queue */
if (rc!= NO_ERROR) {
printf ("DosCloseQueue error: return code = %u\n", rc);
return 1; }
return NO_ERROR;
}