Difference between revisions of "DosExitCritSec"

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==Description==
 
 
Restores normal thread dispatching for the current process.
 
Restores normal thread dispatching for the current process.
  
 
==Syntax==
 
==Syntax==
<PRE>
+
DosExitCritSec ( )
#define INCL_DOSPROCESS
+
#include <os2.h>
+
  
APIRET    ulrc;  /*  Return Code. */
 
 
ulrc = DosExitCritSec();
 
 
</PRE>
 
 
==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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</PRE>
 
</PRE>
==Related Functions==
 
* [[OS2 API:CPI:DosCreateThread|DosCreateThread]]
 
* [[OS2 API:CPI:DosEnterCritSec|DosEnterCritSec]]
 
  
 +
==Related Functions==
 +
* [[DosCreateThread]]
 +
* [[DosEnterCritSec]]
  
[[Category:The OS/2 API Project]]
+
[[Category:Dos]]

Revision as of 05:38, 13 February 2017

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 can enter and exit 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;
    }

Related Functions