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 =
 137                 talloc_get_type_abort(private_data,
 138                 struct tevent_queue);
 139
 140         if (!q->running) {
 141                 return;
 142         }
 143
 144         q->list->triggered = true;
 145         q->list->trigger(q->list->req, q->list->private_data);
 146 }
 147
 148 static struct tevent_queue_entry *tevent_queue_add_internal(
 149                                         struct tevent_queue *queue,
 150                                         struct tevent_context *ev,
 151                                         struct tevent_req *req,
 152                                         tevent_queue_trigger_fn_t trigger,
 153                                         void *private_data,
 154                                         bool allow_direct)
 155 {
 156         struct tevent_queue_entry *e;
 157
 158         e = talloc_zero(req, struct tevent_queue_entry);
 159         if (e == NULL) {
 160                 return NULL;
 161         }
 162
 163         e->queue = queue;
 164         e->req = req;
 165         e->ev = ev;
 166         e->trigger = trigger;
 167         e->private_data = private_data;
 168
 169         /*
 170          * if there is no trigger, it is just a blocker
 171          */
 172         if (trigger == NULL) {
 173                 e->triggered = true;
 174         }
 175
 176         if (queue->length > 0) {
 177                 /*
 178                  * if there are already entries in the
 179                  * queue do not optimize.
 180                  */
 181                 allow_direct = false;
 182         }
 183
 184         if (req->async.fn != NULL) {
 185                 /*
 186                  * If the callers wants to optimize for the
 187                  * empty queue case, call the trigger only
 188                  * if there is no callback defined for the
 189                  * request yet.
 190                  */
 191                 allow_direct = false;
 192         }
 193
 194         DLIST_ADD_END(queue->list, e, struct tevent_queue_entry *);
 195         queue->length++;
 196         talloc_set_destructor(e, tevent_queue_entry_destructor);
 197
 198         if (!queue->running) {
 199                 return e;
 200         }
 201
 202         if (queue->list->triggered) {
 203                 return e;
 204         }
 205
 206         /*
 207          * If allowed we directly call the trigger
 208          * avoiding possible delays caused by
 209          * an immediate event.
 210          */
 211         if (allow_direct) {
 212                 queue->list->triggered = true;
 213                 queue->list->trigger(queue->list->req,
 214                                      queue->list->private_data);
 215                 return e;
 216         }
 217
 218         tevent_schedule_immediate(queue->immediate,
 219                                   queue->list->ev,
 220                                   tevent_queue_immediate_trigger,
 221                                   queue);
 222
 223         return e;
 224 }
 225
 226 bool tevent_queue_add(struct tevent_queue *queue,
 227                       struct tevent_context *ev,
 228                       struct tevent_req *req,
 229                       tevent_queue_trigger_fn_t trigger,
 230                       void *private_data)
 231 {
 232         struct tevent_queue_entry *e;
 233
 234         e = tevent_queue_add_internal(queue, ev, req,
 235                                       trigger, private_data, false);
 236         if (e == NULL) {
 237                 return false;
 238         }
 239
 240         return true;
 241 }
 242
 243 struct tevent_queue_entry *tevent_queue_add_entry(
 244                                         struct tevent_queue *queue,
 245                                         struct tevent_context *ev,
 246                                         struct tevent_req *req,
 247                                         tevent_queue_trigger_fn_t trigger,
 248                                         void *private_data)
 249 {
 250         return tevent_queue_add_internal(queue, ev, req,
 251                                          trigger, private_data, false);
 252 }
 253
 254 struct tevent_queue_entry *tevent_queue_add_optimize_empty(
 255                                         struct tevent_queue *queue,
 256                                         struct tevent_context *ev,
 257                                         struct tevent_req *req,
 258                                         tevent_queue_trigger_fn_t trigger,
 259                                         void *private_data)
 260 {
 261         return tevent_queue_add_internal(queue, ev, req,
 262                                          trigger, private_data, true);
 263 }
 264
 265 void tevent_queue_start(struct tevent_queue *queue)
 266 {
 267         if (queue->running) {
 268                 /* already started */
 269                 return;
 270         }
 271
 272         queue->running = true;
 273
 274         if (!queue->list) {
 275                 return;
 276         }
 277
 278         if (queue->list->triggered) {
 279                 return;
 280         }
 281
 282         tevent_schedule_immediate(queue->immediate,
 283                                   queue->list->ev,
 284                                   tevent_queue_immediate_trigger,
 285                                   queue);
 286 }
 287
 288 void tevent_queue_stop(struct tevent_queue *queue)
 289 {
 290         queue->running = false;
 291 }
 292
 293 size_t tevent_queue_length(struct tevent_queue *queue)
 294 {
 295         return queue->length;
 296 }
 297
 298 bool tevent_queue_running(struct tevent_queue *queue)
 299 {
 300         return queue->running;
 301 }
 302
 303 struct tevent_queue_wait_state {
 304         uint8_t dummy;
 305 };
 306
 307 static void tevent_queue_wait_trigger(struct tevent_req *req,
 308                                       void *private_data);
 309
 310 struct tevent_req *tevent_queue_wait_send(TALLOC_CTX *mem_ctx,
 311                                           struct tevent_context *ev,
 312                                           struct tevent_queue *queue)
 313 {
 314         struct tevent_req *req;
 315         struct tevent_queue_wait_state *state;
 316         bool ok;
 317
 318         req = tevent_req_create(mem_ctx, &state,
 319                                 struct tevent_queue_wait_state);
 320         if (req == NULL) {
 321                 return NULL;
 322         }
 323
 324         ok = tevent_queue_add(queue, ev, req,
 325                               tevent_queue_wait_trigger,
 326                               NULL);
 327         if (!ok) {
 328                 tevent_req_oom(req);
 329                 return tevent_req_post(req, ev);
 330         }
 331
 332         return req;
 333 }
 334
 335 static void tevent_queue_wait_trigger(struct tevent_req *req,
 336                                          void *private_data)
 337 {
 338         tevent_req_done(req);
 339 }
 340
 341 bool tevent_queue_wait_recv(struct tevent_req *req)
 342 {
 343         enum tevent_req_state state;
 344         uint64_t err;
 345
 346         if (tevent_req_is_error(req, &state, &err)) {
 347                 tevent_req_received(req);
 348                 return false;
 349         }
 350
 351         tevent_req_received(req);
 352         return true;
 353 }