Source/charon/queues/event_queue.c

   1 /**
   2  * @file event_queue.c
   3  *
   4  * @brief Event-Queue based on class linked_list_t
   5  *
   6  */
   7
   8 /*
   9  * Copyright (C) 2005 Jan Hutter, Martin Willi
  10  * Hochschule fuer Technik Rapperswil
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License as published by the
  14  * Free Software Foundation; either version 2 of the License, or (at your
  15  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  */
  22
  23 #include <pthread.h>
  24 #include <stdlib.h>
  25
  26 #include "event_queue.h"
  27
  28 #include "../types.h"
  29 #include "../utils/allocator.h"
  30 #include "../utils/linked_list.h"
  31
  32
  33
  34 /**
  35  * @brief Represents an event as it is stored in the event queue.
  36  *
  37  * A event consists of a event time and an assigned job object.
  38  *
  39  */
  40 typedef struct event_s event_t;
  41
  42 struct event_s{
  43         /**
  44          * Time to fire the event.
  45          */
  46         timeval_t time;
  47
  48         /**
  49          * Every event has its assigned job.
  50          */
  51         job_t * job;
  52
  53         /**
  54          * @brief Destroys a event_t object.
  55          *
  56          * @param event_t       calling object
  57          * @returns                     always SUCCESS
  58          */
  59         status_t (*destroy) (event_t *event);
  60 };
  61
  62
  63 /**
  64  * @brief implements function destroy of event_t
  65  */
  66 static status_t event_destroy(event_t *event)
  67 {
  68         allocator_free(event);
  69         return SUCCESS;
  70 }
  71
  72 /**
  73  * @brief Creates a event for a specific time
  74  *
  75  * @param time  absolute time to fire the event
  76  * @param job   job to add to job-queue at specific time
  77  *
  78  * @returns
  79  *                              - created event_t object
  80  *                              - NULL if memory allocation failed
  81  */
  82 static event_t *event_create(timeval_t time, job_t *job)
  83 {
  84         event_t *this = allocator_alloc_thing(event_t);
  85         if (this == NULL)
  86         {
  87                 return this;
  88         }
  89
  90         this->destroy = event_destroy;
  91         this->time = time;
  92         this->job = job;
  93
  94         return this;
  95 }
  96
  97
  98 /**
  99  * @brief Private Variables and Functions of event_queue_t class.
 100  *
 101  */
 102 typedef struct private_event_queue_s private_event_queue_t;
 103
 104
 105 struct private_event_queue_s {
 106         /**
 107          * Public part.
 108          */
 109         event_queue_t public;
 110
 111         /**
 112          * The events are stored in a linked list of type linked_list_t.
 113          */
 114         linked_list_t *list;
 115
 116         /**
 117          * Access to linked_list is locked through this mutex.
 118          */
 119         pthread_mutex_t mutex;
 120
 121         /**
 122          * If the queue is empty or an event has not to be fired
 123          * a thread has to wait.
 124          *
 125          * This condvar is used to wake up such a thread.
 126          */
 127         pthread_cond_t condvar;
 128 };
 129
 130 /**
 131  * Returns the difference of to timeval structs in microseconds
 132  *
 133  * @param end_time              end time
 134  * @param start_time    start time
 135  *
 136  * @warning this function is also defined in the tester class
 137  *                      In later improvements, this function can be added to a general
 138  *          class type!
 139  *
 140  * @return      difference in microseconds (end time - start time)
 141  */
 142 static long time_difference(struct timeval *end_time, struct timeval *start_time)
 143 {
 144         long seconds, microseconds;
 145
 146         seconds = (end_time->tv_sec - start_time->tv_sec);
 147         microseconds = (end_time->tv_usec - start_time->tv_usec);
 148         return ((seconds * 1000000) + microseconds);
 149 }
 150
 151
 152 /**
 153  * Implements function get_count of event_queue_t.
 154  * See #event_queue_s.get_count for description.
 155  */
 156 static int get_count (private_event_queue_t *this)
 157 {
 158         int count;
 159         pthread_mutex_lock(&(this->mutex));
 160         count = this->list->get_count(this->list);
 161         pthread_mutex_unlock(&(this->mutex));
 162         return count;
 163 }
 164
 165 /**
 166  * Implements function get of event_queue_t.
 167  * See #event_queue_s.get for description.
 168  */
 169 static status_t get(private_event_queue_t *this, job_t **job)
 170 {
 171         timespec_t timeout;
 172         timeval_t current_time;
 173         event_t * next_event;
 174         int oldstate;
 175
 176         pthread_mutex_lock(&(this->mutex));
 177
 178         while (1)
 179         {
 180                 while(this->list->get_count(this->list) == 0)
 181                 {
 182                         /* add mutex unlock handler for cancellation, enable cancellation */
 183                         pthread_cleanup_push((void(*)(void*))pthread_mutex_unlock, (void*)&(this->mutex));
 184                         pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
 185
 186                         pthread_cond_wait( &(this->condvar), &(this->mutex));
 187
 188                         /* reset cancellation, remove mutex-unlock handler (without executing) */
 189                         pthread_setcancelstate(oldstate, NULL);
 190                         pthread_cleanup_pop(0);
 191                 }
 192
 193                 this->list->get_first(this->list,(void **) &next_event);
 194
 195                 gettimeofday(&current_time,NULL);
 196                 long difference = time_difference(&current_time,&(next_event->time));
 197                 if (difference <= 0)
 198                 {
 199                         timeout.tv_sec = next_event->time.tv_sec;
 200             timeout.tv_nsec = next_event->time.tv_usec * 1000;
 201
 202                         pthread_cond_timedwait( &(this->condvar), &(this->mutex),&timeout);
 203                 }
 204                 else
 205                 {
 206                         /* event available */
 207                         this->list->remove_first(this->list,(void **) &next_event);
 208
 209                         *job = next_event->job;
 210
 211                         next_event->destroy(next_event);
 212                         break;
 213                 }
 214
 215         }
 216         pthread_cond_signal( &(this->condvar));
 217
 218         pthread_mutex_unlock(&(this->mutex));
 219
 220         return SUCCESS;
 221 }
 222
 223 /**
 224  * Implements function add_absolute of event_queue_t.
 225  * See #event_queue_s.add_absolute for description.
 226  */
 227 static status_t add_absolute(private_event_queue_t *this, job_t *job, timeval_t time)
 228 {
 229         event_t *event = event_create(time,job);
 230         event_t *current_event;
 231         status_t status;
 232
 233         if (event == NULL)
 234         {
 235                 return FAILED;
 236         }
 237         pthread_mutex_lock(&(this->mutex));
 238
 239         /* while just used to break out */
 240         while(1)
 241         {
 242                 if (this->list->get_count(this->list) == 0)
 243                 {
 244                         status = this->list->insert_first(this->list,event);
 245                         break;
 246                 }
 247
 248                 /* check last entry */
 249                 this->list->get_last(this->list,(void **) &current_event);
 250
 251                 if (time_difference(&(event->time), &(current_event->time)) >= 0)
 252                 {
 253                         /* my event has to be fired after the last event in list */
 254                         status = this->list->insert_last(this->list,event);
 255                         break;
 256                 }
 257
 258                 /* check first entry */
 259                 this->list->get_first(this->list,(void **) &current_event);
 260
 261                 if (time_difference(&(event->time), &(current_event->time)) < 0)
 262                 {
 263                         /* my event has to be fired before the first event in list */
 264                         status = this->list->insert_first(this->list,event);
 265                         break;
 266                 }
 267
 268                 linked_list_iterator_t * iterator;
 269
 270                 status = this->list->create_iterator(this->list,&iterator,TRUE);
 271                 if (status != SUCCESS)
 272                 {
 273                         break;
 274                 }
 275
 276
 277                 iterator->has_next(iterator);
 278                 /* first element has not to be checked (already done) */
 279
 280                 while(iterator->has_next(iterator))
 281                 {
 282                         status = iterator->current(iterator,(void **) &current_event);
 283
 284                         if (time_difference(&(event->time), &(current_event->time)) <= 0)
 285                         {
 286                                 /* my event has to be fired before the current event in list */
 287                                 status = this->list->insert_before(this->list,iterator,event);
 288                                 break;
 289                         }
 290                 }
 291                 iterator->destroy(iterator);
 292                 break;
 293         }
 294
 295         pthread_cond_signal( &(this->condvar));
 296         pthread_mutex_unlock(&(this->mutex));
 297
 298         if (status != SUCCESS)
 299         {
 300                 event->destroy(event);
 301         }
 302         return status;
 303 }
 304
 305 /**
 306  * Implements function add_relative of event_queue_t.
 307  * See #event_queue_s.add_relative for description.
 308  */
 309 static status_t add_relative(event_queue_t *this, job_t *job, u_int32_t ms)
 310 {
 311         timeval_t current_time;
 312         timeval_t time;
 313         int micros = ms * 1000;
 314
 315         gettimeofday(&current_time, NULL);
 316
 317         time.tv_usec = ((current_time.tv_usec + micros) % 1000000);
 318         time.tv_sec = current_time.tv_sec + ((current_time.tv_usec + micros)/ 1000000);
 319
 320         return this->add_absolute(this, job, time);
 321 }
 322
 323
 324 /**
 325  * Implements function destroy of event_queue_t.
 326  * See #event_queue_s.destroy for description.
 327  */
 328 static status_t event_queue_destroy(private_event_queue_t *this)
 329 {
 330         while (this->list->get_count(this->list) > 0)
 331         {
 332                 event_t *event;
 333
 334                 if (this->list->remove_first(this->list,(void *) &event) != SUCCESS)
 335                 {
 336                         this->list->destroy(this->list);
 337                         break;
 338                 }
 339                 event->job->destroy(event->job);
 340                 event->destroy(event);
 341         }
 342         this->list->destroy(this->list);
 343
 344         pthread_mutex_destroy(&(this->mutex));
 345
 346         pthread_cond_destroy(&(this->condvar));
 347
 348         allocator_free(this);
 349         return SUCCESS;
 350 }
 351
 352 /*
 353  * Documented in header
 354  */
 355 event_queue_t *event_queue_create()
 356 {
 357         linked_list_t *linked_list = linked_list_create();
 358         if (linked_list == NULL)
 359         {
 360                 return NULL;
 361         }
 362
 363         private_event_queue_t *this = allocator_alloc_thing(private_event_queue_t);
 364         if (this == NULL)
 365         {
 366                 linked_list->destroy(linked_list);
 367                 return NULL;
 368         }
 369
 370         this->public.get_count = (int (*) (event_queue_t *event_queue)) get_count;
 371         this->public.get = (status_t (*) (event_queue_t *event_queue, job_t **job)) get;
 372         this->public.add_absolute = (status_t (*) (event_queue_t *event_queue, job_t *job, timeval_t time)) add_absolute;
 373         this->public.add_relative = (status_t (*) (event_queue_t *event_queue, job_t *job, u_int32_t ms)) add_relative;
 374         this->public.destroy = (status_t (*) (event_queue_t *event_queue)) event_queue_destroy;
 375
 376         this->list = linked_list;
 377         pthread_mutex_init(&(this->mutex), NULL);
 378         pthread_cond_init(&(this->condvar), NULL);
 379
 380         return (&this->public);
 381 }