On Feb 20, 2013 9:16 AM, "Mark Morgan Lloyd" < [email protected]> 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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