release/src/router/dnscrypt/src/libevent-modified/defer-internal.h

   1 /*
   2  * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  * 3. The name of the author may not be used to endorse or promote products
  13  *    derived from this software without specific prior written permission.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26 #ifndef _DEFER_INTERNAL_H_
  27 #define _DEFER_INTERNAL_H_
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 #include "event2/event-config.h"
  34 #include <sys/queue.h>
  35
  36 struct deferred_cb;
  37
  38 typedef void (*deferred_cb_fn)(struct deferred_cb *, void *);
  39
  40 /** A deferred_cb is a callback that can be scheduled to run as part of
  41  * an event_base's event_loop, rather than running immediately. */
  42 struct deferred_cb {
  43         /** Links to the adjacent active (pending) deferred_cb objects. */
  44         TAILQ_ENTRY (deferred_cb) cb_next;
  45         /** True iff this deferred_cb is pending in an event_base. */
  46         unsigned queued : 1;
  47         /** The function to execute when the callback runs. */
  48         deferred_cb_fn cb;
  49         /** The function's second argument. */
  50         void *arg;
  51 };
  52
  53 /** A deferred_cb_queue is a list of deferred_cb that we can add to and run. */
  54 struct deferred_cb_queue {
  55         /** Lock used to protect the queue. */
  56         void *lock;
  57
  58         /** How many entries are in the queue? */
  59         int active_count;
  60
  61         /** Function called when adding to the queue from another thread. */
  62         void (*notify_fn)(struct deferred_cb_queue *, void *);
  63         void *notify_arg;
  64
  65         /** Deferred callback management: a list of deferred callbacks to
  66          * run active the active events. */
  67         TAILQ_HEAD (deferred_cb_list, deferred_cb) deferred_cb_list;
  68 };
  69
  70 /**
  71    Initialize an empty, non-pending deferred_cb.
  72
  73    @param deferred The deferred_cb structure to initialize.
  74    @param cb The function to run when the deferred_cb executes.
  75    @param arg The function's second argument.
  76  */
  77 void event_deferred_cb_init(struct deferred_cb *, deferred_cb_fn, void *);
  78 /**
  79    Cancel a deferred_cb if it is currently scheduled in an event_base.
  80  */
  81 void event_deferred_cb_cancel(struct deferred_cb_queue *, struct deferred_cb *);
  82 /**
  83    Activate a deferred_cb if it is not currently scheduled in an event_base.
  84  */
  85 void event_deferred_cb_schedule(struct deferred_cb_queue *, struct deferred_cb *);
  86
  87 #define LOCK_DEFERRED_QUEUE(q)                                          \
  88         EVLOCK_LOCK((q)->lock, 0)
  89 #define UNLOCK_DEFERRED_QUEUE(q)                                        \
  90         EVLOCK_UNLOCK((q)->lock, 0)
  91
  92 #ifdef __cplusplus
  93 }
  94 #endif
  95
  96 void event_deferred_cb_queue_init(struct deferred_cb_queue *);
  97 struct deferred_cb_queue *event_base_get_deferred_cb_queue(struct event_base *);
  98
  99 #endif /* _EVENT_INTERNAL_H_ */
 100