lib/tevent/tevent_queue.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Infrastructure for async requests
   4    Copyright (C) Volker Lendecke 2008
   5    Copyright (C) Stefan Metzmacher 2009
   6
   7      ** NOTE! The following LGPL license applies to the tevent
   8      ** library. This does NOT imply that all of Samba is released
   9      ** under the LGPL
  10
  11    This library is free software; you can redistribute it and/or
  12    modify it under the terms of the GNU Lesser General Public
  13    License as published by the Free Software Foundation; either
  14    version 3 of the License, or (at your option) any later version.
  15
  16    This library is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Lesser General Public License for more details.
  20
  21    You should have received a copy of the GNU Lesser General Public
  22    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 #include "replace.h"
  26 #include "tevent.h"
  27 #include "tevent_internal.h"
  28 #include "tevent_util.h"
  29
  30 struct tevent_queue_entry {
  31         struct tevent_queue_entry *prev, *next;
  32         struct tevent_queue *queue;
  33
  34         bool triggered;
  35
  36         struct tevent_req *req;
  37         struct tevent_context *ev;
  38
  39         tevent_queue_trigger_fn_t trigger;
  40         void *private_data;
  41 };
  42
  43 struct tevent_queue {
  44         const char *name;
  45         const char *location;
  46
  47         bool running;
  48         struct tevent_immediate *immediate;
  49
  50         size_t length;
  51         struct tevent_queue_entry *list;
  52 };
  53
  54 static void tevent_queue_immediate_trigger(struct tevent_context *ev,
  55                                            struct tevent_immediate *im,
  56                                            void *private_data);
  57
  58 static int tevent_queue_entry_destructor(struct tevent_queue_entry *e)
  59 {
  60         struct tevent_queue *q = e->queue;
  61
  62         if (!q) {
  63                 return 0;
  64         }
  65
  66         DLIST_REMOVE(q->list, e);
  67         q->length--;
  68
  69         if (!q->running) {
  70                 return 0;
  71         }
  72
  73         if (!q->list) {
  74                 return 0;
  75         }
  76
  77         if (q->list->triggered) {
  78                 return 0;
  79         }
  80
  81         tevent_schedule_immediate(q->immediate,
  82                                   q->list->ev,
  83                                   tevent_queue_immediate_trigger,
  84                                   q);
  85
  86         return 0;
  87 }
  88
  89 static int tevent_queue_destructor(struct tevent_queue *q)
  90 {
  91         q->running = false;
  92
  93         while (q->list) {
  94                 struct tevent_queue_entry *e = q->list;
  95                 talloc_free(e);
  96         }
  97
  98         return 0;
  99 }
 100
 101 struct tevent_queue *_tevent_queue_create(TALLOC_CTX *mem_ctx,
 102                                           const char *name,
 103                                           const char *location)
 104 {
 105         struct tevent_queue *queue;
 106
 107         queue = talloc_zero(mem_ctx, struct tevent_queue);
 108         if (!queue) {
 109                 return NULL;
 110         }
 111
 112         queue->name = talloc_strdup(queue, name);
 113         if (!queue->name) {
 114                 talloc_free(queue);
 115                 return NULL;
 116         }
 117         queue->immediate = tevent_create_immediate(queue);
 118         if (!queue->immediate) {
 119                 talloc_free(queue);
 120                 return NULL;
 121         }
 122
 123         queue->location = location;
 124
 125         /* queue is running by default */
 126         queue->running = true;
 127
 128         talloc_set_destructor(queue, tevent_queue_destructor);
 129         return queue;
 130 }
 131
 132 static void tevent_queue_immediate_trigger(struct tevent_context *ev,
 133                                            struct tevent_immediate *im,
 134                                            void *private_data)
 135 {
 136         struct tevent_queue *q = talloc_get_type(private_data,
 137                                   struct tevent_queue);
 138
 139         if (!q->running) {
 140                 return;
 141         }
 142
 143         q->list->triggered = true;
 144         q->list->trigger(q->list->req, q->list->private_data);
 145 }
 146
 147 static struct tevent_queue_entry *tevent_queue_add_internal(
 148                                         struct tevent_queue *queue,
 149                                         struct tevent_context *ev,
 150                                         struct tevent_req *req,
 151                                         tevent_queue_trigger_fn_t trigger,
 152                                         void *private_data)
 153 {
 154         struct tevent_queue_entry *e;
 155
 156         e = talloc_zero(req, struct tevent_queue_entry);
 157         if (e == NULL) {
 158                 return NULL;
 159         }
 160
 161         e->queue = queue;
 162         e->req = req;
 163         e->ev = ev;
 164         e->trigger = trigger;
 165         e->private_data = private_data;
 166
 167         /*
 168          * if there is no trigger, it is just a blocker
 169          */
 170         if (trigger == NULL) {
 171                 e->triggered = true;
 172         }
 173
 174         DLIST_ADD_END(queue->list, e, struct tevent_queue_entry *);
 175         queue->length++;
 176         talloc_set_destructor(e, tevent_queue_entry_destructor);
 177
 178         if (!queue->running) {
 179                 return e;
 180         }
 181
 182         if (queue->list->triggered) {
 183                 return e;
 184         }
 185
 186         tevent_schedule_immediate(queue->immediate,
 187                                   queue->list->ev,
 188                                   tevent_queue_immediate_trigger,
 189                                   queue);
 190
 191         return e;
 192 }
 193
 194 bool tevent_queue_add(struct tevent_queue *queue,
 195                       struct tevent_context *ev,
 196                       struct tevent_req *req,
 197                       tevent_queue_trigger_fn_t trigger,
 198                       void *private_data)
 199 {
 200         struct tevent_queue_entry *e;
 201
 202         e = tevent_queue_add_internal(queue, ev, req,
 203                                       trigger, private_data);
 204         if (e == NULL) {
 205                 return false;
 206         }
 207
 208         return true;
 209 }
 210
 211 void tevent_queue_start(struct tevent_queue *queue)
 212 {
 213         if (queue->running) {
 214                 /* already started */
 215                 return;
 216         }
 217
 218         queue->running = true;
 219
 220         if (!queue->list) {
 221                 return;
 222         }
 223
 224         if (queue->list->triggered) {
 225                 return;
 226         }
 227
 228         tevent_schedule_immediate(queue->immediate,
 229                                   queue->list->ev,
 230                                   tevent_queue_immediate_trigger,
 231                                   queue);
 232 }
 233
 234 void tevent_queue_stop(struct tevent_queue *queue)
 235 {
 236         queue->running = false;
 237 }
 238
 239 size_t tevent_queue_length(struct tevent_queue *queue)
 240 {
 241         return queue->length;
 242 }
 243
 244 bool tevent_queue_running(struct tevent_queue *queue)
 245 {
 246         return queue->running;
 247 }