Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Thu, 31 Oct 2013 12:28:49 +0000

Hi Paul,

> If asynDrvUser->destroy hasn't been defined then this clearly causes a
> problem so:
> 1) Should I always be creating a destroy function?

Yes, you must always define a destroy function for the drvUser interface.

The definition of the interface is:

typedef struct  asynDrvUser {
    /*The following do not have to be called via queueRequest callback*/
    asynStatus (*create)(void *drvPvt,asynUser *pasynUser,
        const char *drvInfo, const char **pptypeName,size_t *psize);
    asynStatus (*getType)(void *drvPvt,asynUser *pasynUser,
        const char **pptypeName,size_t *psize);
    asynStatus (*destroy)(void *drvPvt,asynUser *pasynUser);
}asynDrvUser;

If you have registered the drvUser interface then you must implement all 3 functions.  Clients are not required to check that these function pointers are not NULL.

> 2) Why do only ao records with an AsynFloat64 interface and bo records
> with an AsynUInt32Direct interface call disconnect() in their
> initialisation function?

That is definitely an inconsistency and oversight which has been around for a very long time.  The disconnect() function should be called at the end of all of the record initialization functions that call the XXXSyncIO routines.  However, the penalty for not doing so is a very small amount of memory that gets allocated once and never released, so it is not really a problem.  It is not a memory leak that grows, because the record initialization routines are only called once.

Mark

____________________________
From: [email protected] [[email protected]] on behalf of Paul Hamadyk [[email protected]]
Sent: Thursday, October 31, 2013 5:11 AM
To: [email protected]
Subject: Asyn asynDrvUser interface

I have a question about the asynDrvUser interface. I usually only define
a drvUserCreate function in order to set pasynUser->reason, and I set
drvUserDestroy to NULL. This worked until I added the asynFloat64
interface.

I've noticed that initAo() in devAsynFloat64.c calls
"pasynFloat64SyncIO->disconnect();" which calls
"pioPvt->pasynDrvUser->destroy()" and that initBo() in
devAsynUInt32Direct.c calls "pasynUInt32DigitalSyncIO->disconnect();"
which calls "pioPvt->pasynDrvUser->destroy()".

If asynDrvUser->destroy hasn't been defined then this clearly causes a
problem so:
1) Should I always be creating a destroy function?

static asynStatus drvUserDestroy(void *drvPvt, asynUser *pasynUser)
{
    return asynSuccess;
}

2) Why do only ao records with an AsynFloat64 interface and bo records
with an AsynUInt32Direct interface call disconnect() in their
initialisation function?

Thanks,

Paul.

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System