On Wed, Feb 25, 2009 at 12:23:35PM -0000, Rick Taylor
<[email protected]> wrote:
> Hi, I might be misreading the trunk source code, but is it true that the
> asynchronous event handling uses a single global variable for handling asynch
> events (gotasync in ev.c)?
no, gotasync is simply a global variable to signal an async event - there is
one variable per event in the async watchers.
btw, could you follow your mail messages better in the future? all your
paragraphs are a single long line, which makes it very hard to read it.
> having implemented that, why use a global variable to indicate the
> condition.
it's simple and fast.
> Why not pass a more complex message via the pipe (rather than the single
> int) keeping the notification private to the individual event_loop.
each event loop has it's own pipe and signal variable already and each
async has it's own variable, there is no need for a more complex message
(there is one "int" per async watcher, the best you can do without getting
into atomicity issues).
apart from having no need, the problem is: how do you queue "more complex
messages" (when the pipe is full)? I know of no way to queue anything
in an async-safe way, and so far, nobody has come up with such a method
that is reasonably portable (doesn't require threads for example or
architecture-specific-behaviour).
libev avoids the pipe-full issue by using gotasync to only signal the
condition once, which also saves on syscalls.
> I hope I'm not wasting anyone's time and that I haven't missed the point here.
Not sure if you missed the point :) But if your primary concern is
per-loop-asyncs, then this is already implemented.
--
The choice of a Deliantra, the free code+content MORPG
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----==-- _ generation
---==---(_)__ __ ____ __ Marc Lehmann
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