DosExitCritSec: Difference between revisions
Created page with "==Description== Restores normal thread dispatching for the current process. ==Syntax== <PRE> #define INCL_DOSPROCESS #include <os2.h> APIRET ulrc; →Return Code.: u..." |
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Restores normal thread dispatching for the current process. | Restores normal thread dispatching for the current process. | ||
==Syntax== | ==Syntax== | ||
DosExitCritSec ( ) | |||
==Parameters== | ==Parameters== | ||
none | |||
==Return Code== | ==Return Code== | ||
ulrc (APIRET) - returns | ulrc (APIRET) - returns | ||
DosExitCritSec returns one of the following values: | DosExitCritSec returns one of the following values: | ||
* 0 NO_ERROR | * 0 NO_ERROR | ||
* 309 ERROR_INVALID_THREADID | * 309 ERROR_INVALID_THREADID | ||
* 485 ERROR_CRITSEC_UNDERFLOW | * 485 ERROR_CRITSEC_UNDERFLOW | ||
==Remarks== | ==Remarks== | ||
DosExitCritSec is used following DosEnterCritSec to restore normal thread switching to the threads of a process. | DosExitCritSec is used following [[DosEnterCritSec]] to restore normal thread switching to the threads of a process. | ||
A count is maintained of the number of times DosEnterCritSec is issued without a corresponding DosExitCritSec. The count is incremented by DosEnterCritSec, and decremented by DosExitCritSec. Normal thread dispatching is not restored until the count is zero. | A count is maintained of the number of times DosEnterCritSec is issued without a corresponding DosExitCritSec. The count is incremented by DosEnterCritSec, and decremented by DosExitCritSec. Normal thread dispatching is not restored until the count is zero. | ||
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==Example Code== | ==Example Code== | ||
{{OS2API Example CritSec}} | |||
==Related Functions== | ==Related Functions== | ||
* [[ | * [[DosCreateThread]] | ||
* [[ | * [[DosEnterCritSec]] | ||
[[Category: | [[Category:Dos]] | ||
Latest revision as of 17:20, 15 January 2019
Restores normal thread dispatching for the current process.
Syntax
DosExitCritSec ( )
Parameters
none
Return Code
ulrc (APIRET) - returns
DosExitCritSec returns one of the following values:
- 0 NO_ERROR
- 309 ERROR_INVALID_THREADID
- 485 ERROR_CRITSEC_UNDERFLOW
Remarks
DosExitCritSec is used following DosEnterCritSec to restore normal thread switching to the threads of a process.
A count is maintained of the number of times DosEnterCritSec is issued without a corresponding DosExitCritSec. The count is incremented by DosEnterCritSec, and decremented by DosExitCritSec. Normal thread dispatching is not restored until the count is zero.
The outstanding count is maintained in a word. If an underflow occurs (the count is decremented below zero), the count is set to zero, no operation is performed, and the request returns with ERROR_CRITSEC_UNDERFLOW.
ERROR_INVALID_THREADID is returned when an invalid attempt is made to exit a critical section of code in a signal handler or exception handler.
ERROR_INVALID_THREADID is also returned when a dynamic link library (DLL) routine incorrectly issues DosExitCritSec.
Example Code
This example shows how a thread enters and exits a critical section of code.
#define INCL_DOSPROCESS /* Process values */
#define INCL_DOSERRORS /* Error values */
#include <os2.h>
#include <stdio.h>
int main(VOID)
{
APIRET rc = NO_ERROR; /* Return code */
rc = DosEnterCritSec();
if (rc != NO_ERROR) {
printf("DosEnterCritSec error: return code = %u\n",rc);
return 1;
}
/***********************************************/
/* Add critical section code here. While this */
/* code is running, all other threads are */
/* stopped. CALL NO LIBRARY OR OS/2 FUNCTIONS */
/* HERE UNLESS YOU KNOW THEY DO NOT REQUIRE */
/* ACTION BY ANOTHER THREAD IN THE PROCESS. */
/***********************************************/
rc = DosExitCritSec();
if (rc != NO_ERROR) {
printf("DosExitCritSec error: return code = %u\n",rc);
return 1;
}
return NO_ERROR;
}