tevent in multithreaded programs

Simo simo at samba.org
Fri Jan 30 15:37:39 MST 2015

On Fri, 2015-01-30 at 21:16 +0100, Volker Lendecke wrote:
> On Fri, Jan 30, 2015 at 03:03:25PM -0500, Simo wrote:
> > FWIW, I had a chat with Jeff on IRC and suggest him to use the same
> > approach we use to handle signals.
> > 
> > Namely create a sentinel pipe and add it as fd event, also create a main
> > list that is accessed via mutexes (or other suitable locking or lockless
> > mechanism).
> > When the non-main threads need to add fd events to the main loop, add
> > the fd to the main list then write() 1 byte to the sentinel pipe.
> > The write() will cause the main loop to run a fd handler that will take
> > care of drying up both the pipe and the main list and create appropriate
> > fd events in it.
> Sounds like a plan. Do you really need the "main list"?
> Can't you just write the fd number into the pipe? While it's
> in transit, its ownership might be a bit undefined, but you
> might get away without mutexes.

Maybe if using sendmsg() to avoid having the pipe go out of sync in case
of bugs and trashing any following communication.


Simo Sorce

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