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Comparing libeio/eio.pod (file contents):
Revision 1.11 by root, Mon Jun 20 07:28:15 2011 UTC vs.
Revision 1.16 by root, Tue Jul 5 17:05:54 2011 UTC

… …
124=back 124=back
125 125
126For libev, you would typically use an C<ev_async> watcher: the 126For libev, you would typically use an C<ev_async> watcher: the
127C<want_poll> callback would invoke C<ev_async_send> to wake up the event 127C<want_poll> callback would invoke C<ev_async_send> to wake up the event
128loop. Inside the callback set for the watcher, one would call C<eio_poll 128loop. Inside the callback set for the watcher, one would call C<eio_poll
129()> (followed by C<ev_async_send> again if C<eio_poll> indicates that not 129()>.
130all requests have been handled yet). The race is taken care of because 130
131libev resets/rearms the async watcher before calling your callback, 131If C<eio_poll ()> is configured to not handle all results in one go
132and therefore, before calling C<eio_poll>. This might result in (some) 132(i.e. it returns C<-1>) then you should start an idle watcher that calls
133spurious wake-ups, but is generally harmless. 133C<eio_poll> until it returns something C<!= -1>.
134
135A full-featured conenctor between libeio and libev would look as follows
136(if C<eio_poll> is handling all requests, it can of course be simplified a
137lot by removing the idle watcher logic):
138
139 static struct ev_loop *loop;
140 static ev_idle repeat_watcher;
141 static ev_async ready_watcher;
142
143 /* idle watcher callback, only used when eio_poll */
144 /* didn't handle all results in one call */
145 static void
146 repeat (EV_P_ ev_idle *w, int revents)
147 {
148 if (eio_poll () != -1)
149 ev_idle_stop (EV_A_ w);
150 }
151
152 /* eio has some results, process them */
153 static void
154 ready (EV_P_ ev_async *w, int revents)
155 {
156 if (eio_poll () == -1)
157 ev_idle_start (EV_A_ &repeat_watcher);
158 }
159
160 /* wake up the event loop */
161 static void
162 want_poll (void)
163 {
164 ev_async_send (loop, &ready_watcher)
165 }
166
167 void
168 my_init_eio ()
169 {
170 loop = EV_DEFAULT;
171
172 ev_idle_init (&repeat_watcher, repeat);
173 ev_async_init (&ready_watcher, ready);
174 ev_async_start (loop &watcher);
175
176 eio_init (want_poll, 0);
177 }
134 178
135For most other event loops, you would typically use a pipe - the event 179For most other event loops, you would typically use a pipe - the event
136loop should be told to wait for read readiness on the read end. In 180loop should be told to wait for read readiness on the read end. In
137C<want_poll> you would write a single byte, in C<done_poll> you would try 181C<want_poll> you would write a single byte, in C<done_poll> you would try
138to read that byte, and in the callback for the read end, you would call 182to read that byte, and in the callback for the read end, you would call
139C<eio_poll>. The race is avoided here because the event loop should invoke 183C<eio_poll>.
140your callback again and again until the byte has been read (as the pipe 184
141read callback does not read it, only C<done_poll>). 185You don't have to take special care in the case C<eio_poll> doesn't handle
186all requests, as the done callback will not be invoked, so the event loop
187will still signal readyness for the pipe until I<all> results have been
188processed.
142 189
143 190
144=head1 HIGH LEVEL REQUEST API 191=head1 HIGH LEVEL REQUEST API
145 192
146Libeio has both a high-level API, which consists of calling a request 193Libeio has both a high-level API, which consists of calling a request
… …
153 200
154You submit a request by calling the relevant C<eio_TYPE> function with the 201You submit a request by calling the relevant C<eio_TYPE> function with the
155required parameters, a callback of type C<int (*eio_cb)(eio_req *req)> 202required parameters, a callback of type C<int (*eio_cb)(eio_req *req)>
156(called C<eio_cb> below) and a freely usable C<void *data> argument. 203(called C<eio_cb> below) and a freely usable C<void *data> argument.
157 204
158The return value will either be 0 205The return value will either be 0, in case something went really wrong
206(which can basically only happen on very fatal errors, such as C<malloc>
207returning 0, which is rather unlikely), or a pointer to the newly-created
208and submitted C<eio_req *>.
159 209
160The callback will be called with an C<eio_req *> which contains the 210The callback will be called with an C<eio_req *> which contains the
161results of the request. The members you can access inside that structure 211results of the request. The members you can access inside that structure
162vary from request to request, except for: 212vary from request to request, except for:
163 213
… …
317 char *target = strndup ((char *)req->ptr2, req->result); 367 char *target = strndup ((char *)req->ptr2, req->result);
318 368
319 free (target); 369 free (target);
320 } 370 }
321 371
372=item eio_realpath (const char *path, int pri, eio_cb cb, void *data)
373
374Similar to the realpath libc function, but unlike that one, result is
375C<-1> on failure and the length of the returned path in C<ptr2> (which is
376not 0-terminated) - this is similar to readlink.
377
322=item eio_stat (const char *path, int pri, eio_cb cb, void *data) 378=item eio_stat (const char *path, int pri, eio_cb cb, void *data)
323 379
324=item eio_lstat (const char *path, int pri, eio_cb cb, void *data) 380=item eio_lstat (const char *path, int pri, eio_cb cb, void *data)
325 381
326=item eio_fstat (int fd, int pri, eio_cb cb, void *data) 382=item eio_fstat (int fd, int pri, eio_cb cb, void *data)
… …
568 624
569=back 625=back
570 626
571=head3 GROUPING AND LIMITING REQUESTS 627=head3 GROUPING AND LIMITING REQUESTS
572 628
629There is one more rather special request, C<eio_grp>. It is a very special
630aio request: Instead of doing something, it is a container for other eio
631requests.
632
633There are two primary use cases for this: a) bundle many requests into a
634single, composite, request with a definite callback and the ability to
635cancel the whole request with its subrequests and b) limiting the number
636of "active" requests.
637
638Further below you will find more dicussion of these topics - first follows
639the reference section detailing the request generator and other methods.
640
641=over 4
642
643=item eio_grp (eio_cb cb, void *data)
644
645Creates and submits a group request.
646
647=back
648
649
650
573#TODO 651#TODO
574 652
575/*****************************************************************************/ 653/*****************************************************************************/
576/* groups */ 654/* groups */
577 655

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