Using Time Outs

The following example demonstrates the use of timeout and LAP handlers. The example assumes that the program is run in supervisor mode.

Example 12-3 Using Timeout/LAP Handlers

In this example, the original value of val is 10. The example includes the following steps:

• A LAP is created, which doubles the value of val when it is called and posts an event.

• The main program installs the LAP, sets a timeout and waits for a semaphore.

• After being awakened, the program completes its function and then exits.

#include <exec/chExec.h>
#include <exec/chIo.h>
#include <stdcIntf.h>
#include <stdio.h>
#include <exec/chTimeout.h>


int              result;
int              val;


KnTimeVal  servTimeout = {0,   50 * K_NPERM}; /* 50 millisec */


KnTimeVal  servDelay =   {0,  500 * K_NPERM}; /* 5000 millisec */

KnTimeout servTimeoutDesc;
KnThSem servThSem;

   /*
    * Timeout handler, used to test 
    */
    void
toHandler(args, opMsg)
    void* args;
    void* opMsg;
{
     val = val * 2;
     threadSemPost(&servThSem);
     sysWrite("timeout handler", strlen("timeout handler"));
}

    void 
timeout() 
{
    void *opMsg;


        if (_stdc_execPrivilege == K_SUPACTOR) {
                KnLapDesc lapDesc;
                result = svLapCreate(&_stdc_execActor, toHandler, 
                                     opMsg, K_LAP_SAMEHOST, &lapDesc);
                if (result != K_EOK) {
                    printf("svLapCreate error\n");
                }

                result = svSysTimeoutSet(&servTimeoutDesc, &servTimeout, 
                                         0, &lapDesc);
                if (result != K_EOK) {
                    printf("svSysTimeoutSet error\n");
                }
                    /* Wait for the timeout handler to complete.
                       should NOT return K_ETIMEOUT */
                result = threadSemWait(&servThSem, &servDelay);
                if (result != K_EOK) {
                    printf("threadSemWait error \n");
                }
                printf("timeout completed\n");
        }
}


main(int argc, char* argv[], char** envp)
{
    val = 10;
    printf("val = %d\n",val);
    threadSemInit(&servThSem);
    timeout();
    printf("val = %d\n",val);
}