lib/eventslib.php

   1 <?php
   2 /**
   3  * Library of functions for events manipulation.
   4  *
   5  * The public API is all at the end of this file.
   6  *
   7  * @author Martin Dougiamas and many others
   8  * @version $Id$
   9  * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
  10  * @package moodlecore
  11  */
  12
  13
  14 /**
  15  * Loads the events definitions for the component (from file). If no
  16  * events are defined for the component, we simply return an empty array.
  17  * @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
  18  * @return array of capabilities or empty array if not exists
  19  *
  20  * INTERNAL - to be used from eventslib only
  21  */
  22 function events_load_def($component) {
  23     global $CFG;
  24
  25     if ($component == 'moodle') {
  26         $defpath = $CFG->libdir.'/db/events.php';
  27
  28     } else if ($component == 'unittest') {
  29         $defpath = $CFG->libdir.'/simpletest/fixtures/events.php';
  30
  31     } else {
  32         $compparts = explode('/', $component);
  33
  34         if ($compparts[0] == 'block') {
  35             // Blocks are an exception. Blocks directory is 'blocks', and not
  36             // 'block'. So we need to jump through hoops.
  37             $defpath = $CFG->dirroot.'/blocks/'.$compparts[1].'/db/events.php';
  38
  39         } else if ($compparts[0] == 'format') {
  40             // Similar to the above, course formats are 'format' while they
  41             // are stored in 'course/format'.
  42             $defpath = $CFG->dirroot.'/course/format/'.$compparts[1].'/db/events.php';
  43
  44         } else if ($compparts[0] == 'gradeimport') {
  45             $defpath = $CFG->dirroot.'/grade/import/'.$compparts[1].'/db/events.php';
  46
  47         } else if ($compparts[0] == 'gradeexport') {
  48             $defpath = $CFG->dirroot.'/grade/export/'.$compparts[1].'/db/events.php';
  49
  50         } else if ($compparts[0] == 'gradereport') {
  51             $defpath = $CFG->dirroot.'/grade/report/'.$compparts[1].'/db/events.php';
  52
  53         } else {
  54             $defpath = $CFG->dirroot.'/'.$component.'/db/events.php';
  55         }
  56     }
  57
  58     $handlers = array();
  59
  60     if (file_exists($defpath)) {
  61         require($defpath);
  62     }
  63
  64     return $handlers;
  65 }
  66
  67 /**
  68  * Gets the capabilities that have been cached in the database for this
  69  * component.
  70  * @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
  71  * @return array of events
  72  *
  73  * INTERNAL - to be used from eventslib only
  74  */
  75 function events_get_cached($component) {
  76     $cachedhandlers = array();
  77
  78     if ($storedhandlers = get_records('events_handlers', 'handlermodule', $component)) {
  79         foreach ($storedhandlers as $handler) {
  80             $cachedhandlers[$handler->eventname] = array (
  81                 'id'              => $handler->id,
  82                 'handlerfile'     => $handler->handlerfile,
  83                 'handlerfunction' => $handler->handlerfunction,
  84                 'schedule'        => $handler->schedule);
  85         }
  86     }
  87
  88     return $cachedhandlers;
  89 }
  90
  91 /**
  92  * We can not removed all event handlers in table, then add them again
  93  * because event handlers could be referenced by queued items
  94  *
  95  * Note that the absence of the db/events.php event definition file
  96  * will cause any queued events for the component to be removed from
  97  * the database.
  98  *
  99  * @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
 100  * @return boolean
 101  */
 102 function events_update_definition($component='moodle') {
 103
 104     // load event definition from events.php
 105     $filehandlers = events_load_def($component);
 106
 107     // load event definitions from db tables
 108     // if we detect an event being already stored, we discard from this array later
 109     // the remaining needs to be removed
 110     $cachedhandlers = events_get_cached($component);
 111
 112     foreach ($filehandlers as $eventname => $filehandler) {
 113         if (!empty($cachedhandlers[$eventname])) {
 114             if ($cachedhandlers[$eventname]['handlerfile'] == $filehandler['handlerfile'] &&
 115                 $cachedhandlers[$eventname]['handlerfunction'] == serialize($filehandler['handlerfunction']) &&
 116                 $cachedhandlers[$eventname]['schedule'] == $filehandler['schedule']) {
 117                 // exact same event handler already present in db, ignore this entry
 118
 119                 unset($cachedhandlers[$eventname]);
 120                 continue;
 121
 122             } else {
 123                 // same event name matches, this event has been updated, update the datebase
 124                 $handler = new object();
 125                 $handler->id              = $cachedhandlers[$eventname]['id'];
 126                 $handler->handlerfile     = $filehandler['handlerfile'];
 127                 $handler->handlerfunction = serialize($filehandler['handlerfunction']); // static class methods stored as array
 128                 $handler->schedule        = $filehandler['schedule'];
 129
 130                 update_record('events_handlers', $handler);
 131
 132                 unset($cachedhandlers[$eventname]);
 133                 continue;
 134             }
 135
 136         } else {
 137             // if we are here, this event handler is not present in db (new)
 138             // add it
 139             $handler = new object();
 140             $handler->eventname       = $eventname;
 141             $handler->handlermodule   = $component;
 142             $handler->handlerfile     = $filehandler['handlerfile'];
 143             $handler->handlerfunction = serialize($filehandler['handlerfunction']); // static class methods stored as array
 144             $handler->schedule        = $filehandler['schedule'];
 145
 146             insert_record('events_handlers', $handler);
 147         }
 148     }
 149
 150     // clean up the left overs, the entries in cachedevents array at this points are deprecated event handlers
 151     // and should be removed, delete from db
 152     events_cleanup($component, $cachedhandlers);
 153
 154     return true;
 155 }
 156
 157 /**
 158  * Remove all event handlers and queued events
 159  * @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
 160  */
 161 function events_uninstall($component) {
 162     $cachedhandlers = events_get_cached($component);
 163     events_cleanup($component, $cachedhandlers);
 164 }
 165
 166 /**
 167  * Deletes cached events that are no longer needed by the component.
 168  * @param $component - examples: 'moodle', 'mod/forum', 'block/quiz_results'
 169  * @param $chachedevents - array of the cached events definitions that will be
 170  * @return int - number of deprecated capabilities that have been removed
 171  *
 172  * INTERNAL - to be used from eventslib only
 173  */
 174 function events_cleanup($component, $cachedhandlers) {
 175     $deletecount = 0;
 176     foreach ($cachedhandlers as $eventname => $cachedhandler) {
 177         if ($qhandlers = get_records('events_queue_handlers', 'handlerid', $cachedhandler['id'])) {
 178             debugging("Removing pending events from queue before deleting of event handler: $component - $eventname");
 179             foreach ($qhandlers as $qhandler) {
 180                 events_dequeue($qhandler);
 181             }
 182         }
 183         if (delete_records('events_handlers', 'eventname', $eventname, 'handlermodule', $component)) {
 184             $deletecount++;
 185         }
 186     }
 187
 188     // reset static handler cache
 189     events_get_handlers('reset');
 190
 191     return $deletecount;
 192 }
 193
 194 /****************** End of Events handler Definition code *******************/
 195
 196 /**
 197  * puts a handler on queue
 198  * @param object handler - event handler object from db
 199  * @param object eventdata - event data object
 200  * @return id number of new queue handler
 201  *
 202  * INTERNAL - to be used from eventslib only
 203  */
 204 function events_queue_handler($handler, $event, $errormessage) {
 205
 206     if ($qhandler = get_record('events_queue_handlers', 'queuedeventid', $event->id, 'handlerid', $handler->id)) {
 207         debugging("Please check code: Event id $event->id is already queued in handler id $qhandler->id");
 208         return $qhandler->id;
 209     }
 210
 211     // make a new queue handler
 212     $qhandler = new object();
 213     $qhandler->queuedeventid  = $event->id;
 214     $qhandler->handlerid      = $handler->id;
 215     $qhandler->errormessage   = addslashes($errormessage);
 216     $qhandler->timemodified   = time();
 217     if ($handler->schedule == 'instant' and $handler->status == 1) {
 218         $qhandler->status     = 1; //already one failed attempt to dispatch this event
 219     } else {
 220         $qhandler->status     = 0;
 221     }
 222
 223     return insert_record('events_queue_handlers', $qhandler);
 224 }
 225
 226 /**
 227  * trigger a single event with a specified handler
 228  * @param handler - hander object from db
 229  * @param eventdata - event dataobject
 230  * @param errormessage - error message indicating problem
 231  * @return bool - success or fail
 232  *
 233  * INTERNAL - to be used from eventslib only
 234  */
 235 function events_dispatch($handler, $eventdata, &$errormessage) {
 236     global $CFG;
 237
 238     $function = unserialize($handler->handlerfunction);
 239
 240     if (is_callable($function)) {
 241         // oki, no need for includes
 242
 243     } else if (file_exists($CFG->dirroot.$handler->handlerfile)) {
 244         include_once($CFG->dirroot.$handler->handlerfile);
 245
 246     } else {
 247         $errormessage = "Handler file of component $handler->handlermodule: $handler->handlerfile can not be found!";
 248         return false;
 249     }
 250
 251     // checks for handler validity
 252     if (is_callable($function)) {
 253         return call_user_func($function, $eventdata);
 254
 255     } else {
 256         $errormessage = "Handler function of component $handler->handlermodule: $handler->handlerfunction not callable function or class method!";
 257         return false;
 258     }
 259 }
 260
 261 /**
 262  * given a queued handler, call the respective event handler to process the event
 263  * @param object qhandler - events_queued_handler object from db
 264  * @return boolean meaning success, or NULL on fatal failure
 265  *
 266  * INTERNAL - to be used from eventslib only
 267  */
 268 function events_process_queued_handler($qhandler) {
 269     global $CFG;
 270
 271     // get handler
 272     if (!$handler = get_record('events_handlers', 'id', $qhandler->handlerid)) {
 273         debugging("Error processing queue handler $qhandler->id, missing handler id: $qhandler->handlerid");
 274         //irrecoverable error, remove broken queue handler
 275         events_dequeue($qhandler);
 276         return NULL;
 277     }
 278
 279     // get event object
 280     if (!$event = get_record('events_queue', 'id', $qhandler->queuedeventid)) {
 281         // can't proceed with no event object - might happen when two crons running at the same time
 282         debugging("Error processing queue handler $qhandler->id, missing event id: $qhandler->queuedeventid");
 283         //irrecoverable error, remove broken queue handler
 284         events_dequeue($qhandler);
 285         return NULL;
 286     }
 287
 288     // call the function specified by the handler
 289     $errormessage = 'Unknown error';
 290     if (events_dispatch($handler, unserialize($event->eventdata), $errormessage)) {
 291         //everything ok
 292         events_dequeue($qhandler);
 293         return true;
 294
 295     } else {
 296         //dispatching failed
 297         $qh = new object();
 298         $qh->id           = $qhandler->id;
 299         $qh->errormessage = addslashes($errormessage);
 300         $qh->timemodified = time();
 301         $qh->status       = $qhandler->status + 1;
 302         update_record('events_queue_handlers', $qh);
 303         return false;
 304     }
 305 }
 306
 307 /**
 308  * removes this queued handler from the events_queued_handler table
 309  * removes events_queue record from events_queue if no more references to this event object exists
 310  * @param object qhandler - events_queued_handler object from db
 311  *
 312  * INTERNAL - to be used from eventslib only
 313  */
 314 function events_dequeue($qhandler) {
 315     // first delete the queue handler
 316     delete_records('events_queue_handlers', 'id', $qhandler->id);
 317
 318     // if no more queued handler is pointing to the same event - delete the event too
 319     if (!record_exists('events_queue_handlers', 'queuedeventid', $qhandler->queuedeventid)) {
 320         delete_records('events_queue', 'id', $qhandler->queuedeventid);
 321     }
 322 }
 323
 324 /**
 325  * Returns hanflers for given event. Uses caching for better perf.
 326  * @param string $eventanme name of even or 'reset'
 327  * @return mixed array of handlers or false otherwise
 328  *
 329  * INTERNAL - to be used from eventslib only
 330  */
 331 function events_get_handlers($eventname) {
 332     static $handlers = array();
 333
 334     if ($eventname == 'reset') {
 335         $handlers = array();
 336         return false;
 337     }
 338
 339     if (!array_key_exists($eventname, $handlers)) {
 340         $handlers[$eventname] = get_records('events_handlers', 'eventname', $eventname);
 341     }
 342
 343     return $handlers[$eventname];
 344 }
 345
 346 /****** Public events API starts here, do not use functions above in 3rd party code ******/
 347
 348
 349 /**
 350  * Events cron will try to empty the events queue by processing all the queued events handlers
 351  * @param string eventname - empty means all
 352  * @return number of dispatched+removed broken events
 353  *
 354  * PUBLIC
 355  */
 356 function events_cron($eventname='') {
 357     global $CFG;
 358
 359     $failed = array();
 360     $processed = 0;
 361
 362     if ($eventname) {
 363         $sql = "SELECT qh.* FROM {$CFG->prefix}events_queue_handlers qh, {$CFG->prefix}events_handlers h
 364                 WHERE qh.handlerid = h.id AND h.eventname='$eventname'
 365                 ORDER BY qh.id";
 366     } else {
 367         $sql = "SELECT * FROM {$CFG->prefix}events_queue_handlers
 368                 ORDER BY id";
 369     }
 370
 371     if ($rs = get_recordset_sql($sql)) {
 372         while ($qhandler = rs_fetch_next_record($rs)) {
 373             if (in_array($qhandler->handlerid, $failed)) {
 374                 // do not try to dispatch any later events when one already failed
 375                 continue;
 376             }
 377             $status = events_process_queued_handler($qhandler);
 378             if ($status === false) {
 379                 $failed[] = $qhandler->handlerid;
 380             } else {
 381                 $processed++;
 382             }
 383         }
 384         rs_close($rs);
 385     }
 386     return $processed;
 387 }
 388
 389
 390 /**
 391  * Function to call all eventhandlers when triggering an event
 392  * @param eventname - name of the event
 393  * @param eventdata - event data object (without magic quotes)
 394  * @return number of failed events
 395  *
 396  * PUBLIC
 397  */
 398 function events_trigger($eventname, $eventdata) {
 399     global $CFG, $USER;
 400
 401     $failedcount = 0; // number of failed events.
 402     $event = false;
 403
 404     // pull out all registered event handlers
 405     if ($handlers = events_get_handlers($eventname)) {
 406         foreach ($handlers as $handler) {
 407
 408            $errormessage = '';
 409
 410            if ($handler->schedule == 'instant') {
 411                 if ($handler->status) {
 412                     //check if previous pending events processed
 413                     if (!record_exists('events_queue_handlers', 'handlerid', $handler->id)) {
 414                         // ok, queue is empty, lets reset the status back to 0 == ok
 415                         $handler->status = 0;
 416                         set_field('events_handlers', 'status', 0, 'id', $handler->id);
 417                     }
 418                 }
 419
 420                 // dispatch the event only if instant schedule and status ok
 421                 if (!$handler->status) {
 422                     $errormessage = 'Unknown error';;
 423                     if (events_dispatch($handler, $eventdata, $errormessage)) {
 424                         continue;
 425                     }
 426                     // set error count to 1 == send next instant into cron queue
 427                     set_field('events_handlers', 'status', 1, 'id', $handler->id);
 428
 429                 } else {
 430                     // increment the error status counter
 431                     $handler->status++;
 432                     set_field('events_handlers', 'status', $handler->status, 'id', $handler->id);
 433                 }
 434
 435                 // update the failed counter
 436                 $failedcount ++;
 437
 438             } else if ($handler->schedule == 'cron') {
 439                 //ok - use queuing of events only
 440
 441             } else {
 442                 // unknown schedule - fallback to cron type
 443                 debugging("Unknown handler schedule type: $handler->schedule");
 444             }
 445
 446             // if even type is not instant, or dispatch failed, queue it
 447             if ($event === false) {
 448                 $event = new object();
 449                 $event->userid      = $USER->id;
 450                 $event->eventdata   = addslashes(serialize($eventdata));
 451                 $event->timecreated = time();
 452                 if (debugging()) {
 453                     $dump = '';
 454                     $callers = debug_backtrace();
 455                     foreach ($callers as $caller) {
 456                         $dump .= 'line ' . $caller['line'] . ' of ' . substr($caller['file'], strlen($CFG->dirroot) + 1);
 457                         if (isset($caller['function'])) {
 458                             $dump .= ': call to ';
 459                             if (isset($caller['class'])) {
 460                                 $dump .= $caller['class'] . $caller['type'];
 461                             }
 462                             $dump .= $caller['function'] . '()';
 463                         }
 464                         $dump .= "\n";
 465                     }
 466                     $event->stackdump = addslashes($dump);
 467                } else {
 468                     $event->stackdump = '';
 469                 }
 470                 $event->id = insert_record('events_queue', $event);
 471             }
 472             events_queue_handler($handler, $event, $errormessage);
 473         }
 474     } else {
 475         //debugging("No handler found for event: $eventname");
 476     }
 477
 478     return $failedcount;
 479 }
 480
 481 /**
 482  * checks if an event is registered for this component
 483  * @param string eventname - name of the event
 484  * @param string component - component name, can be mod/data or moodle
 485  * @return bool
 486  *
 487  * PUBLIC
 488  */
 489 function events_is_registered($eventname, $component) {
 490     return record_exists('events_handlers', 'handlermodule', $component, 'eventname', $eventname);
 491 }
 492
 493 /**
 494  * checks if an event is queued for processing - either cron handlers attached or failed instant handlers
 495  * @param string eventname - name of the event
 496  * @return int number of queued events
 497  *
 498  * PUBLIC
 499  */
 500 function events_pending_count($eventname) {
 501     global $CFG;
 502
 503     $sql = "SELECT COUNT(*) FROM {$CFG->prefix}events_queue_handlers qh, {$CFG->prefix}events_handlers h
 504             WHERE qh.handlerid = h.id AND h.eventname='$eventname'";
 505     return count_records_sql($sql);
 506 }
 507 ?>