Re: Area Detector Destructors

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

Hi Mark,


My understanding is that the destructor (dtor) won't be called because the objects are allocated on the heap not on the stack so they won't go out of scope.  Here is the simDetector allocation for example:


/** Configuration command, called directly or from iocsh */
extern "C" int simDetectorConfig(const char *portName, int maxSizeX, int maxSizeY, int dataType,
                                 int maxBuffers, int maxMemory, int priority, int stackSize)
{
    new simDetector(portName, maxSizeX, maxSizeY, (NDDataType_t)dataType,
                    (maxBuffers < 0) ? 0 : maxBuffers,
                    (maxMemory < 0) ? 0 : maxMemory,
                    priority, stackSize);
    return(asynSuccess);
}

Currently if you want to run the dtor you need to establish an exit handler, typically with epicsAtExit().

Perhaps the base class (asynPortDriver?) should establish an exit handler in its ctor and call the dtor for you?  If we did that and the derived class also has an exit handler then the derived class exit handler will be called first.  How does the base class then determine that the dtor has already been called and the pointer it receives in the exit handler callback is no longer valid?

Mark





________________________________
From: Mark Engbretson <engbretson@anl.gov>
Sent: Tuesday, December 12, 2017 10:08 AM
To: Mark Rivers
Cc: 'EPICS tech-talk'
Subject: Area Detector Destructors


Mark -



Should destructors be being called when Area Detectors shutdown (I don't seem to see that happening) or do you have to do what a few AD's have done and create an exit handler if you need to perform any sort of cleanup.



I have a camera with a FPGA which runs *hot* when it is being used, so shutting it down when the AD exits or aborts might prevent it from baking itself.  Trace code never seems to be hit in the destructor.