Timeout for msg indications

[stephane]

Copied from https://answers.launchpad.net/libmodbus/+question/193271

Hi, I just bumped into the same problem. In older versions, there was a timeout in the select() call, so it was possible to properly stop a thread waiting for an indication, update watchdog, whatever. The commit that changes this is:

commit 89d0dc0
Author: Stéphane Raimbault [email protected]
Date: Fri May 6 19:06:59 2011 +0200

    Fix longstanding limitation of server to wait forever

    The change for serial on Windows is temporary. If you're interested of
    improving the situation for this, please have a look at the FIXME.

So, in some cases (like mine: ) this limitation was not so undesirable. Now in the code we have a hardcored value of NULL if we're waiting for an idication:

  if (msg_type == MSG_INDICATION) {
         /* Wait for a message, we don't know when the message will be
          * received */
        p_tv = NULL;
     } else {
         tv.tv_sec = ctx->response_timeout.tv_sec;
         tv.tv_usec = ctx->response_timeout.tv_usec;
         p_tv = &tv;
     }

I think it will be better to make this configurable, like the other timeouts. So, what do you think about changing it to somethink like:

  if (msg_type == MSG_INDICATION) {
         /* Wait for a message, we don't know when the message will be
          * received */
         if (ctx->indication_timeout.tv_usec==-1) {
         p_tv=NULL;
         } else {
         tv.tv_sec = ctx->indication_timeout.tv_sec;
         tv.tv_usec = ctx->indication_timeout.tv_usec;
         p_tv = &tv;
         }
     } else {
         tv.tv_sec = ctx->response_timeout.tv_sec;
         tv.tv_usec = ctx->response_timeout.tv_usec;
         p_tv = &tv;
     }

And the default value for indication_timeout can be NULL, so it will wait forever. But for some of us who need a timeout there will be a way to set it.

[bertonimatias]

Dear Stephane,

i must add the parameter "ctx->indication_timeout.tv_usec" in the struct _modbus

I don´t know if this issus has relation with my issus #233

[jfieldhouse]

Is it possible for me to get this patch now? Instead of waiting for the next milestone? I need it to kick a watchdog in my modbus server application.

[stephane]

@jfieldhouse yep feel free to patch your Modbus server, the Open Source way!

[stephane]

Could someone review my patch?

[stephane]

Merged.