Hi Andrew,
Thanks for your prompt. Moments ago, I wrote a client to open the .fifo
file and write data to it and finally drive the event-loop run!
I guess I must further my research into the kernel before I completely
understand how epoll/select etc cooperate with file descriptor:(
Thanks for your help
Harvey
2011/8/3 Andrew W. Nosenko <[email protected]>
> On Wed, Aug 3, 2011 at 15:57, zhihua che <[email protected]> wrote:
> > Hi, Adrian,
> > Thanks for your reply. However, what you said makes me more
> confused:(
> > You mean the mechanism behind libevent like epoll doesn't support
> > regular file descriptor? I'm not sure whether you're right, but looking
> into
>
> poll/select/etc technically support regular file descriptors. There
> no error to pass regular FDs to them. It just useless because regular
> file always available for read and always available for write
> (assuming that file opened for read and write respectively).
> Therefore, callbacks bound to such descriptors will be called at ever
> event-loop round.
>
> > the application sample given by the libevent official
> > website, http://monkey.org/~provos/libevent/event-test.c, I found this
> > sample using libevent on the local file 'event.fifo', and this is where
> my
> > confusion came from, so I guess I must further my reading to find more
> > proof:)
>
> 'event.fifo' in event-test.c is not a regular file. It is FIFO (named
> pipe, special filesystem object). You can see it by inspecing
> following snippet:
>
> around lines 96-108: if filesystem object with given name exists, and
> is a regular file, then report error and exit; otherwise create or
> recreate it as FIFO:
>
> if (lstat(fifo, &st) == 0) {
> if ((st.st_mode & S_IFMT) == S_IFREG) {
> errno = EEXIST;
> perror("lstat");
> exit(1);
> }
> }
>
> unlink(fifo);
> if (mkfifo(fifo, 0600) == -1) {
> perror("mkfifo");
> exit(1);
> }
>
> --
> Andrew W. Nosenko <[email protected]>
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