release/src/router/dnscrypt/src/libevent/event-internal.h

   1 /*
   2  * Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
   3  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
   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 #ifndef _EVENT_INTERNAL_H_
  28 #define _EVENT_INTERNAL_H_
  29
  30 #ifdef __cplusplus
  31 extern "C" {
  32 #endif
  33
  34 #include "event2/event-config.h"
  35 #include <time.h>
  36 #include <sys/queue.h>
  37 #include "event2/event_struct.h"
  38 #include "minheap-internal.h"
  39 #include "evsignal-internal.h"
  40 #include "mm-internal.h"
  41 #include "defer-internal.h"
  42
  43 /* map union members back */
  44
  45 /* mutually exclusive */
  46 #define ev_signal_next  _ev.ev_signal.ev_signal_next
  47 #define ev_io_next      _ev.ev_io.ev_io_next
  48 #define ev_io_timeout   _ev.ev_io.ev_timeout
  49
  50 /* used only by signals */
  51 #define ev_ncalls       _ev.ev_signal.ev_ncalls
  52 #define ev_pncalls      _ev.ev_signal.ev_pncalls
  53
  54 /* Possible values for ev_closure in struct event. */
  55 #define EV_CLOSURE_NONE 0
  56 #define EV_CLOSURE_SIGNAL 1
  57 #define EV_CLOSURE_PERSIST 2
  58
  59 /** Structure to define the backend of a given event_base. */
  60 struct eventop {
  61         /** The name of this backend. */
  62         const char *name;
  63         /** Function to set up an event_base to use this backend.  It should
  64          * create a new structure holding whatever information is needed to
  65          * run the backend, and return it.  The returned pointer will get
  66          * stored by event_init into the event_base.evbase field.  On failure,
  67          * this function should return NULL. */
  68         void *(*init)(struct event_base *);
  69         /** Enable reading/writing on a given fd or signal.  'events' will be
  70          * the events that we're trying to enable: one or more of EV_READ,
  71          * EV_WRITE, EV_SIGNAL, and EV_ET.  'old' will be those events that
  72          * were enabled on this fd previously.  'fdinfo' will be a structure
  73          * associated with the fd by the evmap; its size is defined by the
  74          * fdinfo field below.  It will be set to 0 the first time the fd is
  75          * added.  The function should return 0 on success and -1 on error.
  76          */
  77         int (*add)(struct event_base *, evutil_socket_t fd, short old, short events, void *fdinfo);
  78         /** As "add", except 'events' contains the events we mean to disable. */
  79         int (*del)(struct event_base *, evutil_socket_t fd, short old, short events, void *fdinfo);
  80         /** Function to implement the core of an event loop.  It must see which
  81             added events are ready, and cause event_active to be called for each
  82             active event (usually via event_io_active or such).  It should
  83             return 0 on success and -1 on error.
  84          */
  85         int (*dispatch)(struct event_base *, struct timeval *);
  86         /** Function to clean up and free our data from the event_base. */
  87         void (*dealloc)(struct event_base *);
  88         /** Flag: set if we need to reinitialize the event base after we fork.
  89          */
  90         int need_reinit;
  91         /** Bit-array of supported event_method_features that this backend can
  92          * provide. */
  93         enum event_method_feature features;
  94         /** Length of the extra information we should record for each fd that
  95             has one or more active events.  This information is recorded
  96             as part of the evmap entry for each fd, and passed as an argument
  97             to the add and del functions above.
  98          */
  99         size_t fdinfo_len;
 100 };
 101
 102 #ifdef WIN32
 103 /* If we're on win32, then file descriptors are not nice low densely packed
 104    integers.  Instead, they are pointer-like windows handles, and we want to
 105    use a hashtable instead of an array to map fds to events.
 106 */
 107 #define EVMAP_USE_HT
 108 #endif
 109
 110 /* #define HT_CACHE_HASH_VALS */
 111
 112 #ifdef EVMAP_USE_HT
 113 #include "ht-internal.h"
 114 struct event_map_entry;
 115 HT_HEAD(event_io_map, event_map_entry);
 116 #else
 117 #define event_io_map event_signal_map
 118 #endif
 119
 120 /* Used to map signal numbers to a list of events.  If EVMAP_USE_HT is not
 121    defined, this structure is also used as event_io_map, which maps fds to a
 122    list of events.
 123 */
 124 struct event_signal_map {
 125         /* An array of evmap_io * or of evmap_signal *; empty entries are
 126          * set to NULL. */
 127         void **entries;
 128         /* The number of entries available in entries */
 129         int nentries;
 130 };
 131
 132 /* A list of events waiting on a given 'common' timeout value.  Ordinarily,
 133  * events waiting for a timeout wait on a minheap.  Sometimes, however, a
 134  * queue can be faster.
 135  **/
 136 struct common_timeout_list {
 137         /* List of events currently waiting in the queue. */
 138         struct event_list events;
 139         /* 'magic' timeval used to indicate the duration of events in this
 140          * queue. */
 141         struct timeval duration;
 142         /* Event that triggers whenever one of the events in the queue is
 143          * ready to activate */
 144         struct event timeout_event;
 145         /* The event_base that this timeout list is part of */
 146         struct event_base *base;
 147 };
 148
 149 /** Mask used to get the real tv_usec value from a common timeout. */
 150 #define COMMON_TIMEOUT_MICROSECONDS_MASK       0x000fffff
 151
 152 struct event_change;
 153
 154 /* List of 'changes' since the last call to eventop.dispatch.  Only maintained
 155  * if the backend is using changesets. */
 156 struct event_changelist {
 157         struct event_change *changes;
 158         int n_changes;
 159         int changes_size;
 160 };
 161
 162 #ifndef _EVENT_DISABLE_DEBUG_MODE
 163 /* Global internal flag: set to one if debug mode is on. */
 164 extern int _event_debug_mode_on;
 165 #define EVENT_DEBUG_MODE_IS_ON() (_event_debug_mode_on)
 166 #else
 167 #define EVENT_DEBUG_MODE_IS_ON() (0)
 168 #endif
 169
 170 struct event_base {
 171         /** Function pointers and other data to describe this event_base's
 172          * backend. */
 173         const struct eventop *evsel;
 174         /** Pointer to backend-specific data. */
 175         void *evbase;
 176
 177         /** List of changes to tell backend about at next dispatch.  Only used
 178          * by the O(1) backends. */
 179         struct event_changelist changelist;
 180
 181         /** Function pointers used to describe the backend that this event_base
 182          * uses for signals */
 183         const struct eventop *evsigsel;
 184         /** Data to implement the common signal handelr code. */
 185         struct evsig_info sig;
 186
 187         /** Number of virtual events */
 188         int virtual_event_count;
 189         /** Number of total events added to this event_base */
 190         int event_count;
 191         /** Number of total events active in this event_base */
 192         int event_count_active;
 193
 194         /** Set if we should terminate the loop once we're done processing
 195          * events. */
 196         int event_gotterm;
 197         /** Set if we should terminate the loop immediately */
 198         int event_break;
 199         /** Set if we should start a new instance of the loop immediately. */
 200         int event_continue;
 201
 202         /** The currently running priority of events */
 203         int event_running_priority;
 204
 205         /** Set if we're running the event_base_loop function, to prevent
 206          * reentrant invocation. */
 207         int running_loop;
 208
 209         /* Active event management. */
 210         /** An array of nactivequeues queues for active events (ones that
 211          * have triggered, and whose callbacks need to be called).  Low
 212          * priority numbers are more important, and stall higher ones.
 213          */
 214         struct event_list *activequeues;
 215         /** The length of the activequeues array */
 216         int nactivequeues;
 217
 218         /* common timeout logic */
 219
 220         /** An array of common_timeout_list* for all of the common timeout
 221          * values we know. */
 222         struct common_timeout_list **common_timeout_queues;
 223         /** The number of entries used in common_timeout_queues */
 224         int n_common_timeouts;
 225         /** The total size of common_timeout_queues. */
 226         int n_common_timeouts_allocated;
 227
 228         /** List of defered_cb that are active.  We run these after the active
 229          * events. */
 230         struct deferred_cb_queue defer_queue;
 231
 232         /** Mapping from file descriptors to enabled (added) events */
 233         struct event_io_map io;
 234
 235         /** Mapping from signal numbers to enabled (added) events. */
 236         struct event_signal_map sigmap;
 237
 238         /** All events that have been enabled (added) in this event_base */
 239         struct event_list eventqueue;
 240
 241         /** Stored timeval; used to detect when time is running backwards. */
 242         struct timeval event_tv;
 243
 244         /** Priority queue of events with timeouts. */
 245         struct min_heap timeheap;
 246
 247         /** Stored timeval: used to avoid calling gettimeofday/clock_gettime
 248          * too often. */
 249         struct timeval tv_cache;
 250
 251 #if defined(_EVENT_HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
 252         /** Difference between internal time (maybe from clock_gettime) and
 253          * gettimeofday. */
 254         struct timeval tv_clock_diff;
 255         /** Second in which we last updated tv_clock_diff, in monotonic time. */
 256         time_t last_updated_clock_diff;
 257 #endif
 258
 259 #ifndef _EVENT_DISABLE_THREAD_SUPPORT
 260         /* threading support */
 261         /** The thread currently running the event_loop for this base */
 262         unsigned long th_owner_id;
 263         /** A lock to prevent conflicting accesses to this event_base */
 264         void *th_base_lock;
 265         /** The event whose callback is executing right now */
 266         struct event *current_event;
 267         /** A condition that gets signalled when we're done processing an
 268          * event with waiters on it. */
 269         void *current_event_cond;
 270         /** Number of threads blocking on current_event_cond. */
 271         int current_event_waiters;
 272 #endif
 273
 274 #ifdef WIN32
 275         /** IOCP support structure, if IOCP is enabled. */
 276         struct event_iocp_port *iocp;
 277 #endif
 278
 279         /** Flags that this base was configured with */
 280         enum event_base_config_flag flags;
 281
 282         /* Notify main thread to wake up break, etc. */
 283         /** True if the base already has a pending notify, and we don't need
 284          * to add any more. */
 285         int is_notify_pending;
 286         /** A socketpair used by some th_notify functions to wake up the main
 287          * thread. */
 288         evutil_socket_t th_notify_fd[2];
 289         /** An event used by some th_notify functions to wake up the main
 290          * thread. */
 291         struct event th_notify;
 292         /** A function used to wake up the main thread from another thread. */
 293         int (*th_notify_fn)(struct event_base *base);
 294 };
 295
 296 struct event_config_entry {
 297         TAILQ_ENTRY(event_config_entry) next;
 298
 299         const char *avoid_method;
 300 };
 301
 302 /** Internal structure: describes the configuration we want for an event_base
 303  * that we're about to allocate. */
 304 struct event_config {
 305         TAILQ_HEAD(event_configq, event_config_entry) entries;
 306
 307         int n_cpus_hint;
 308         enum event_method_feature require_features;
 309         enum event_base_config_flag flags;
 310 };
 311
 312 /* Internal use only: Functions that might be missing from <sys/queue.h> */
 313 #if defined(_EVENT_HAVE_SYS_QUEUE_H) && !defined(_EVENT_HAVE_TAILQFOREACH)
 314 #ifndef TAILQ_FIRST
 315 #define TAILQ_FIRST(head)               ((head)->tqh_first)
 316 #endif
 317 #ifndef TAILQ_END
 318 #define TAILQ_END(head)                 NULL
 319 #endif
 320 #ifndef TAILQ_NEXT
 321 #define TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 322 #endif
 323
 324 #ifndef TAILQ_FOREACH
 325 #define TAILQ_FOREACH(var, head, field)                                 \
 326         for ((var) = TAILQ_FIRST(head);                                 \
 327              (var) != TAILQ_END(head);                                  \
 328              (var) = TAILQ_NEXT(var, field))
 329 #endif
 330
 331 #ifndef TAILQ_INSERT_BEFORE
 332 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 333         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 334         (elm)->field.tqe_next = (listelm);                              \
 335         *(listelm)->field.tqe_prev = (elm);                             \
 336         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 337 } while (0)
 338 #endif
 339 #endif /* TAILQ_FOREACH */
 340
 341 #define N_ACTIVE_CALLBACKS(base)                                        \
 342         ((base)->event_count_active + (base)->defer_queue.active_count)
 343
 344 int _evsig_set_handler(struct event_base *base, int evsignal,
 345                           void (*fn)(int));
 346 int _evsig_restore_handler(struct event_base *base, int evsignal);
 347
 348
 349 void event_active_nolock(struct event *ev, int res, short count);
 350
 351 /* FIXME document. */
 352 void event_base_add_virtual(struct event_base *base);
 353 void event_base_del_virtual(struct event_base *base);
 354
 355 /** For debugging: unless assertions are disabled, verify the referential
 356     integrity of the internal data structures of 'base'.  This operation can
 357     be expensive.
 358
 359     Returns on success; aborts on failure.
 360 */
 361 void event_base_assert_ok(struct event_base *base);
 362
 363 #ifdef __cplusplus
 364 }
 365 #endif
 366
 367 #endif /* _EVENT_INTERNAL_H_ */
 368