RE: asynManager isConnected

[Mark Rivers <rivers@cars.uchicago.edu>]

Just to clarify one point:

>  So when another port was set up by asynPortDriver, and a new asynUser structure created, my pointer was pointing to this new structure.

asynManager maintains a pool of asynUser structures.  When pasynOctetSyncIO->disconnect(*ppasynUser) is called that asynUser structure is returned to the pool.  When pasynManager->createAsynUser is called later it does not necessarily need to create a new structure, it can allocate an existing structure from the pool if the pool is not empty.  It's a good idea to set your pasynUser pointer to NULL after calling pasynManager->freeAsynUser or pasynXXXSyncIO->disconnect(), which in turn calls pasynManager->freeAsynUser.

Mark


-----Original Message-----
From: matthew.pearson@diamond.ac.uk [mailto:matthew.pearson@diamond.ac.uk] 
Sent: Tuesday, July 17, 2012 6:39 AM
To: tech-talk@aps.anl.gov
Cc: Mark Rivers
Subject: RE: asynManager isConnected

Hi,

Just posting a follow up to this problem. Mark suggested some additional tests I could do to diagnose it.

The original problem was that the pasynManager->isConnected() function was saying the IP port was connected even though I initialized it with a non-valid IP address.

What was happening was that I issued a asynOctetSyncIO->connect() call on the IP port, and then attempted to set the EOS parameters, which failed because the port wasn't connected. And then I disconnected the port, like this:

status = pasynOctetSyncIO->setInputEos(*ppasynUser, inputEos, strlen(inputEos) );
if (status) {
  asynPrint(this->pasynUserSelf, ASYN_TRACE_ERROR,
	      "drvPmacCreate: unable to set input EOS on %s: %s\n", 
	      port, (*ppasynUser)->errorMessage);
  pasynOctetSyncIO->disconnect(*ppasynUser);
  return status;
}

So, the asynUser structure was freed by asynManager. However, my pointer to it was still valid. So when another port was set up by asynPortDriver, and a new asynUser structure created, my pointer was pointing to this new structure. And since this new structure was connected ok, asynManager->isConnected() returned true.

Cheers,
Matt


> -----Original Message-----
> From: Mark Rivers [mailto:rivers@cars.uchicago.edu]
> Sent: 02 June 2012 17:54
> To: J. Lewis Muir; Pearson, Matthew (DLSLtd,RAL,DIA)
> Cc: tech-talk@aps.anl.gov
> Subject: RE: asynManager isConnected
> 
> > I don't know of a function in Asyn that allows one to determine
> > whether the IP socket is connected.  I always just determine
> > this based on the asynStatus returned from a read or write.  But
> > maybe there's a way that I don't know about?
> 
> pasynManager->isConnected() will tell you this.
> 
> It will return 1 when the underlying driver has most recently called
> pasynManager->exceptionConnect().  It will return 0 when the underlying
> driver has most recently called pasynManager->exceptionDisconnect().
> Note that it can take some time after an IP device is disconnected
> (network cable unplugged etc.) before the drvAsynIPPortDriver can
> determine that the device is disconnected and calls pasynManager-
> >exceptionDisconnect().  During this time the client will receive
> timeout messages, rather than disconnected messages.
> 
> To illustrate this, I have run the test program I posted in my last
> message with a 4'th case: the IP device is initially available, and
> then reboots, and becomes available again:
> 
> 2012/06/02 11:47:40.425 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:47:41.426 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:41.426 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:47:42.426 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:42.427 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:47:43.427 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:43.427 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:47:44.427 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:44.428 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:47:45.428 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:46.429 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:47.429 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:48.430 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:49.430 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:50.431 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:51.431 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:52.432 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:53.432 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:54.433 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:55.433 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:56.434 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=1, error=newport-xps5:5001 timeout:
> Resource temporarily unavailable
> 2012/06/02 11:47:57.434 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:58.177 testConnect:pollerTask: error calling
> pasynOctetSyncIO->writeRead, status=3, error=newport-xps5:5001 read
> error: Connection reset by peer
> 2012/06/02 11:47:59.177 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:47:59.178 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:48:00.178 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:48:00.179 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:48:01.179 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:48:01.179 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 2012/06/02 11:48:02.179 testConnect:pollerTask: isConnected = 1
> 2012/06/02 11:48:02.180 testConnect:pollerTask: numWrite=26, wrote:
> FirmwareVersionGet(char *), numRead=60, response=0,XPS-Q8 Firmware
> Precision Platform V1.0.0 Beta 27,EndOfAPI
> 
> 
> Note that initially the device is connected, isConnected=1 and the I/O
> succeeds.  Then the device is rebooted.  For the next 10 seconds or so
> isConnected is still 1, but the I/O returns a timeout error and the
> error "Resource temporarily unavailable".  Then the device reconnects
> and things proceed normally.  If the device had remained off-line for
> longer eventually the IP driver would have detected that the device was
> not available and called pasynManager->exceptionDisconnect().  At that
> time isConnected would have been 0.
> 
> Mark
> 
> 
> 
> Mark
> ________________________________________
> From: tech-talk-bounces@aps.anl.gov [tech-talk-bounces@aps.anl.gov] on
> behalf of J. Lewis Muir [jlmuir@imca-cat.org]
> Sent: Friday, June 01, 2012 10:18 AM
> To: matthew.pearson@diamond.ac.uk
> Cc: tech-talk@aps.anl.gov
> Subject: Re: asynManager isConnected
> 
> On 6/1/12 6:17 AM, matthew.pearson@diamond.ac.uk wrote:
> > Hi,
> >
> > I'm trying to use asynManager isConnected() to test whether or not an
> IP port is connected to a device. But I'm finding that isConnected()
> only seems to report the connected status of the asynUser structure to
> the underlying device.
> >
> > If I attempt to call drvAsynIPPort on an IP address that has nothing
> connected to it, the connection fails. Then I attempt to connect an
> asynUser to this port using asynOctetSyncIO connect(), which also
> fails. Then I call asynManager isConnected a few times, and I find that
> the first few calls return false, and then after iocInit it returns
> true. But still, in the background, asynManager is attempting to
> connect to the IP port via the autoConnect feature.
> >
> > Is this behaviour correct?
> >
> > I can get around it by maintaining connected status myself. But the
> documentation seems to indicate that isConnected() shouldn't return
> true if the IP port is not connected.
> 
> Hi, Matt.
> 
> I'm sure Mark Rivers or someone else will give a more helpful
> response, but I'll just share what I usually do.
> 
> If I want to write an IP client that handles connecting and
> disconnecting of an IP socket, I do the following:
> 
> 1. Ensure that auto-connect is disabled for the ASYN IP port
> 
> 2. Create and attach an asynUser to the ASYN port using
>    pasynOctetSyncIO->connect
> 
> 3. Create and attach an asynUser for the pasynCommonSyncIO
>    interface using pasynCommonSyncIO->connect
> 
> 4. Establish the IP socket connection (using the
>    pasynCommonSyncIO asynUser) using
>    pasynCommonSyncIO->connectDevice
> 
> 5. I can now use the pasynOctetSyncIO asynUser for reading and
>    writing on the IP socket.
> 
> If I don't want to handle connecting and disconnecting of an IP
> socket myself, I enable auto-connect for the ASYN port and don't
> make any attempt at connecting or disconnecting the IP socket
> since that would interfere with the auto-connect functionality.
> 
> I don't know of a function in Asyn that allows one to determine
> whether the IP socket is connected.  I always just determine
> this based on the asynStatus returned from a read or write.  But
> maybe there's a way that I don't know about?
> 
> Lewis

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