unbound/util/mini_event.h

   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 */
  96 struct event_base
  97 {
  98         /** sorted by timeout (absolute), ptr */
  99         rbtree_t* 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  */
 129 struct event {
 130         /** node in timeout rbtree */
 131         rbnode_t 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 */
 152 void *event_init(time_t* time_secs, struct timeval* time_tv);
 153 /** get version */
 154 const char *event_get_version(void);
 155 /** get polling method, select */
 156 const char *event_get_method(void);
 157 /** run select in a loop */
 158 int event_base_dispatch(struct event_base *);
 159 /** exit that loop */
 160 int event_base_loopexit(struct event_base *, struct timeval *);
 161 /** free event base. Free events yourself */
 162 void event_base_free(struct event_base *);
 163 /** set content of event */
 164 void event_set(struct event *, int, short, void (*)(int, short, void *), void *);
 165 /** add event to a base. You *must* call this for every event. */
 166 int event_base_set(struct event_base *, struct event *);
 167 /** add event to make it active. You may not change it with event_set anymore */
 168 int event_add(struct event *, struct timeval *);
 169 /** remove event. You may change it again */
 170 int 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 */
 180 int 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 */
 185 int 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 */
 190 int mini_ev_cmp(const void* a, const void* b);
 191
 192 #endif /* MINI_EVENT_H */