mini_event.h revision 269257 
1/*
2 * mini-event.h - micro implementation of libevent api, using select() only.
3 *
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36/**
37 * \file
38 * This file implements part of the event(3) libevent api.
39 * The back end is only select. Max number of fds is limited.
40 * Max number of signals is limited, one handler per signal only.
41 * And one handler per fd.
42 *
43 * Although limited to select() and a max (1024) open fds, it
44 * is efficient:
45 * o dispatch call caches fd_sets to use.
46 * o handler calling takes time ~ to the number of fds.
47 * o timeouts are stored in a redblack tree, sorted, so take log(n).
48 * Timeouts are only accurate to the second (no subsecond accuracy).
49 * To avoid cpu hogging, fractional timeouts are rounded up to a whole second.
50 */
51
52#ifndef MINI_EVENT_H
53#define MINI_EVENT_H
54
55#if defined(USE_MINI_EVENT) && !defined(USE_WINSOCK)
56
57#ifndef HAVE_EVENT_BASE_FREE
58#define HAVE_EVENT_BASE_FREE
59#endif
60
61/** event timeout */
62#define EV_TIMEOUT	0x01
63/** event fd readable */
64#define EV_READ		0x02
65/** event fd writable */
66#define EV_WRITE	0x04
67/** event signal */
68#define EV_SIGNAL	0x08
69/** event must persist */
70#define EV_PERSIST	0x10
71
72/* needs our redblack tree */
73#include "rbtree.h"
74
75/** max number of file descriptors to support */
76#define MAX_FDS 1024
77/** max number of signals to support */
78#define MAX_SIG 32
79
80/** event base */
81struct event_base
82{
83	/** sorted by timeout (absolute), ptr */
84	rbtree_t* times;
85	/** array of 0 - maxfd of ptr to event for it */
86	struct event** fds;
87	/** max fd in use */
88	int maxfd;
89	/** capacity - size of the fds array */
90	int capfd;
91	/* fdset for read write, for fds ready, and added */
92	fd_set
93		/** fds for reading */
94		reads,
95		/** fds for writing */
96		writes,
97		/** fds determined ready for use */
98		ready,
99		/** ready plus newly added events. */
100		content;
101	/** array of 0 - maxsig of ptr to event for it */
102	struct event** signals;
103	/** if we need to exit */
104	int need_to_exit;
105	/** where to store time in seconds */
106	time_t* time_secs;
107	/** where to store time in microseconds */
108	struct timeval* time_tv;
109};
110
111/**
112 * Event structure. Has some of the event elements.
113 */
114struct event {
115	/** node in timeout rbtree */
116	rbnode_t node;
117	/** is event already added */
118	int added;
119
120	/** event base it belongs to */
121	struct event_base *ev_base;
122	/** fd to poll or -1 for timeouts. signal number for sigs. */
123	int ev_fd;
124	/** what events this event is interested in, see EV_.. above. */
125	short ev_events;
126	/** timeout value */
127	struct timeval ev_timeout;
128
129	/** callback to call: fd, eventbits, userarg */
130	void (*ev_callback)(int, short, void *arg);
131	/** callback user arg */
132	void *ev_arg;
133};
134
135/* function prototypes (some are as they appear in event.h) */
136/** create event base */
137void *event_init(time_t* time_secs, struct timeval* time_tv);
138/** get version */
139const char *event_get_version(void);
140/** get polling method, select */
141const char *event_get_method(void);
142/** run select in a loop */
143int event_base_dispatch(struct event_base *);
144/** exit that loop */
145int event_base_loopexit(struct event_base *, struct timeval *);
146/** free event base. Free events yourself */
147void event_base_free(struct event_base *);
148/** set content of event */
149void event_set(struct event *, int, short, void (*)(int, short, void *), void *);
150/** add event to a base. You *must* call this for every event. */
151int event_base_set(struct event_base *, struct event *);
152/** add event to make it active. You may not change it with event_set anymore */
153int event_add(struct event *, struct timeval *);
154/** remove event. You may change it again */
155int event_del(struct event *);
156
157/** add a timer */
158#define evtimer_add(ev, tv)             event_add(ev, tv)
159/** remove a timer */
160#define evtimer_del(ev)                 event_del(ev)
161
162/* uses different implementation. Cannot mix fd/timeouts and signals inside
163 * the same struct event. create several event structs for that.  */
164/** install signal handler */
165int signal_add(struct event *, struct timeval *);
166/** set signal event contents */
167#define signal_set(ev, x, cb, arg)      \
168        event_set(ev, x, EV_SIGNAL|EV_PERSIST, cb, arg)
169/** remove signal handler */
170int signal_del(struct event *);
171
172#endif /* USE_MINI_EVENT and not USE_WINSOCK */
173
174/** compare events in tree, based on timevalue, ptr for uniqueness */
175int mini_ev_cmp(const void* a, const void* b);
176
177#endif /* MINI_EVENT_H */
178