[Lazarus] Signal handling

[Henry Vermaak]

On Feb 20, 2013 9:16 AM, "Mark Morgan Lloyd" <
markMLl.lazarus at telemetry.co.uk> wrote:
>
> Mark Morgan Lloyd wrote:
>>>
>>> If I want to poll a variable set by an asynchronous unix-style signal,
i.e. that doesn't have an OS-level handle and where the latency should
probably be of the order of 100mSec, what's the most effective technique?
>
>
> > If I understand correctly, the self pipe trick is probably best, then
> > you don't have to poll, just add the handle to select().
>
> But there's no handle, simply a (global) variable. This continues from an
earlier discussion where Sven was cautioning that about the only thing you
could do safely in a signal handler was set a (global) variable: that bit I
knew, but I don't know how best to deal with the variable once set if
there's no convenient timer etc. (I should have threaded the question onto
that, but I thought it was on a different list).

You create the pipe, add the read end fd to select, write a byte to the
write end fd in the signal handler.  There are a bunch of examples floating
around on the web.

Henry
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