Re: Waveform record I/O interrupt. asyn

[Benjamin Franksen <benjamin.franksen@helmholtz-berlin.de>]

On Friday, February 21, 2014 23:06:57 Mark Rivers wrote:
> For non-array records the asyn device support has a "ring buffer" that
> stores a certain number of callback values from the driver.  The
> default ring buffer size is 10.  In this case if several driver
> callbacks happen faster than the scanIORequest can complete the
> record will post monitors on all of them.  But eventually if the
> callbacks happen too fast the ring buffer will overflow and values
> will be lost.

> For array records like you are using there is no ring buffer, because
> the size could be very large and it would involve copying a large
> amount of data.

There is no need to do large amounts of copying. You simply have to
allocate a new array before filling it with new data, instead of
overwriting a previously allocated one. Then all the arrays can be
easily and safely cached/buffered/queued by reference. Indeed there is
no need to *ever* copy such an array except, maybe, when finally sending
it over the network.

Cheers
Ben
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