1 /*
2  * Copyright (c) 2002-2004 Niels Provos <provos@citi.umich.edu>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include <sys/time.h>
29 #include <event.h>
30 #include "config.h"
31 
32 void bufferevent_read_pressure_cb(struct evbuffer *, size_t, size_t,
33     void *);
34 
35 static int
36 bufferevent_add(struct event *ev, int timeout)
37 {
38 	struct timeval tv, *ptv = NULL;
39 
40 	if (timeout) {
41 		timerclear(&tv);
42 		tv.tv_sec = timeout;
43 		ptv = &tv;
44 	}
45 
46 	return (event_add(ev, ptv));
47 }
48 
49 /*
50  * This callback is executed when the size of the input buffer changes.
51  * We use it to apply back pressure on the reading side.
52  */
53 void
54 bufferevent_read_pressure_cb(struct evbuffer *buf, size_t old, size_t now,
55     void *arg) {
56 	struct bufferevent *bufev = arg;
57 	/*
58 	 * If we are below the watermark then reschedule reading if it's
59 	 * still enabled.
60 	 */
61 	if (bufev->wm_read.high == 0 || now < bufev->wm_read.high) {
62 		evbuffer_setcb(buf, NULL, NULL);
63 
64 		if (bufev->enabled & EV_READ)
65 #if HAVE_LIBEVENT2
66 			bufferevent_add(&bufev->ev_read,
67 			    bufev->timeout_read.tv_sec);
68 #else
69 			bufferevent_add(&bufev->ev_read, bufev->timeout_read);
70 #endif
71 	}
72 }