mini_event.h revision 356345 
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/* redefine to use our own namespace so that on platforms where
62 * linkers crosslink library-private symbols with other symbols, it works */
63#define event_init minievent_init
64#define event_get_version minievent_get_version
65#define event_get_method minievent_get_method
66#define event_base_dispatch minievent_base_dispatch
67#define event_base_loopexit minievent_base_loopexit
68#define event_base_free minievent_base_free
69#define event_set minievent_set
70#define event_base_set minievent_base_set
71#define event_add minievent_add
72#define event_del minievent_del
73#define signal_add minisignal_add
74#define signal_del minisignal_del
75
76/** event timeout */
77#define EV_TIMEOUT	0x01
78/** event fd readable */
79#define EV_READ		0x02
80/** event fd writable */
81#define EV_WRITE	0x04
82/** event signal */
83#define EV_SIGNAL	0x08
84/** event must persist */
85#define EV_PERSIST	0x10
86
87/* needs our redblack tree */
88#include "rbtree.h"
89
90/** max number of file descriptors to support */
91#define MAX_FDS 1024
92/** max number of signals to support */
93#define MAX_SIG 32
94
95/** event base */
96struct event_base
97{
98	/** sorted by timeout (absolute), ptr */
99	rbtree_type* times;
100	/** array of 0 - maxfd of ptr to event for it */
101	struct event** fds;
102	/** max fd in use */
103	int maxfd;
104	/** capacity - size of the fds array */
105	int capfd;
106	/* fdset for read write, for fds ready, and added */
107	fd_set
108		/** fds for reading */
109		reads,
110		/** fds for writing */
111		writes,
112		/** fds determined ready for use */
113		ready,
114		/** ready plus newly added events. */
115		content;
116	/** array of 0 - maxsig of ptr to event for it */
117	struct event** signals;
118	/** if we need to exit */
119	int need_to_exit;
120	/** where to store time in seconds */
121	time_t* time_secs;
122	/** where to store time in microseconds */
123	struct timeval* time_tv;
124};
125
126/**
127 * Event structure. Has some of the event elements.
128 */
129struct event {
130	/** node in timeout rbtree */
131	rbnode_type node;
132	/** is event already added */
133	int added;
134
135	/** event base it belongs to */
136	struct event_base *ev_base;
137	/** fd to poll or -1 for timeouts. signal number for sigs. */
138	int ev_fd;
139	/** what events this event is interested in, see EV_.. above. */
140	short ev_events;
141	/** timeout value */
142	struct timeval ev_timeout;
143
144	/** callback to call: fd, eventbits, userarg */
145	void (*ev_callback)(int, short, void *arg);
146	/** callback user arg */
147	void *ev_arg;
148};
149
150/* function prototypes (some are as they appear in event.h) */
151/** create event base */
152void *event_init(time_t* time_secs, struct timeval* time_tv);
153/** get version */
154const char *event_get_version(void);
155/** get polling method, select */
156const char *event_get_method(void);
157/** run select in a loop */
158int event_base_dispatch(struct event_base *);
159/** exit that loop */
160int event_base_loopexit(struct event_base *, struct timeval *);
161/** free event base. Free events yourself */
162void event_base_free(struct event_base *);
163/** set content of event */
164void event_set(struct event *, int, short, void (*)(int, short, void *), void *);
165/** add event to a base. You *must* call this for every event. */
166int event_base_set(struct event_base *, struct event *);
167/** add event to make it active. You may not change it with event_set anymore */
168int event_add(struct event *, struct timeval *);
169/** remove event. You may change it again */
170int event_del(struct event *);
171
172/** add a timer */
173#define evtimer_add(ev, tv)             event_add(ev, tv)
174/** remove a timer */
175#define evtimer_del(ev)                 event_del(ev)
176
177/* uses different implementation. Cannot mix fd/timeouts and signals inside
178 * the same struct event. create several event structs for that.  */
179/** install signal handler */
180int signal_add(struct event *, struct timeval *);
181/** set signal event contents */
182#define signal_set(ev, x, cb, arg)      \
183        event_set(ev, x, EV_SIGNAL|EV_PERSIST, cb, arg)
184/** remove signal handler */
185int signal_del(struct event *);
186
187#endif /* USE_MINI_EVENT and not USE_WINSOCK */
188
189/** compare events in tree, based on timevalue, ptr for uniqueness */
190int mini_ev_cmp(const void* a, const void* b);
191
192#endif /* MINI_EVENT_H */
193