gio/gfilemonitor.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2006-2007 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Author: Alexander Larsson <alexl@redhat.com>
  21  */
  22
  23 #include "config.h"
  24 #include <string.h>
  25
  26 #include "gfilemonitor.h"
  27 #include "gioenumtypes.h"
  28 #include "gfile.h"
  29 #include "gvfs.h"
  30 #include "glibintl.h"
  31
  32
  33 struct _FileChange;
  34 typedef struct _FileChange FileChange;
  35 static void file_change_free (FileChange *change);
  36
  37 /**
  38  * SECTION:gfilemonitor
  39  * @short_description: File Monitor
  40  * @include: gio/gio.h
  41  *
  42  * Monitors a file or directory for changes.
  43  *
  44  * To obtain a #GFileMonitor for a file or directory, use
  45  * g_file_monitor(), g_file_monitor_file(), or
  46  * g_file_monitor_directory().
  47  *
  48  * To get informed about changes to the file or directory you are
  49  * monitoring, connect to the #GFileMonitor::changed signal. The
  50  * signal will be emitted in the <link
  51  * linkend="g-main-context-push-thread-default">thread-default main
  52  * context</link> of the thread that the monitor was created in
  53  * (though if the global default main context is blocked, this may
  54  * cause notifications to be blocked even if the thread-default
  55  * context is still running).
  56  **/
  57
  58 G_LOCK_DEFINE_STATIC(cancelled);
  59
  60 enum {
  61   CHANGED,
  62   LAST_SIGNAL
  63 };
  64
  65 typedef struct {
  66   GFile *file;
  67   guint32 last_sent_change_time; /* 0 == not sent */
  68   guint32 send_delayed_change_at; /* 0 == never */
  69   guint32 send_virtual_changes_done_at; /* 0 == never */
  70 } RateLimiter;
  71
  72 struct _GFileMonitorPrivate {
  73   gboolean cancelled;
  74   int rate_limit_msec;
  75
  76   /* Rate limiting change events */
  77   GHashTable *rate_limiter;
  78
  79   GMutex mutex;
  80   GSource *pending_file_change_source;
  81   GSList *pending_file_changes; /* FileChange */
  82
  83   GSource *timeout;
  84   guint32 timeout_fires_at;
  85
  86   GMainContext *context;
  87 };
  88
  89 enum {
  90   PROP_0,
  91   PROP_RATE_LIMIT,
  92   PROP_CANCELLED
  93 };
  94
  95 /* work around a limitation of the aliasing foo */
  96 #undef g_file_monitor
  97
  98 G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GFileMonitor, g_file_monitor, G_TYPE_OBJECT)
  99
 100 static void
 101 g_file_monitor_set_property (GObject      *object,
 102                              guint         prop_id,
 103                              const GValue *value,
 104                              GParamSpec   *pspec)
 105 {
 106   GFileMonitor *monitor;
 107
 108   monitor = G_FILE_MONITOR (object);
 109
 110   switch (prop_id)
 111     {
 112     case PROP_RATE_LIMIT:
 113       g_file_monitor_set_rate_limit (monitor, g_value_get_int (value));
 114       break;
 115
 116     default:
 117       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 118       break;
 119     }
 120 }
 121
 122 static void
 123 g_file_monitor_get_property (GObject    *object,
 124                              guint       prop_id,
 125                              GValue     *value,
 126                              GParamSpec *pspec)
 127 {
 128   GFileMonitor *monitor;
 129   GFileMonitorPrivate *priv;
 130
 131   monitor = G_FILE_MONITOR (object);
 132   priv = monitor->priv;
 133
 134   switch (prop_id)
 135     {
 136     case PROP_RATE_LIMIT:
 137       g_value_set_int (value, priv->rate_limit_msec);
 138       break;
 139
 140     case PROP_CANCELLED:
 141       G_LOCK (cancelled);
 142       g_value_set_boolean (value, priv->cancelled);
 143       G_UNLOCK (cancelled);
 144       break;
 145
 146     default:
 147       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 148       break;
 149     }
 150 }
 151
 152 #define DEFAULT_RATE_LIMIT_MSECS 800
 153 #define DEFAULT_VIRTUAL_CHANGES_DONE_DELAY_SECS 2
 154
 155 static guint signals[LAST_SIGNAL] = { 0 };
 156
 157 static void
 158 rate_limiter_free (RateLimiter *limiter)
 159 {
 160   g_object_unref (limiter->file);
 161   g_slice_free (RateLimiter, limiter);
 162 }
 163
 164 static void
 165 g_file_monitor_finalize (GObject *object)
 166 {
 167   GFileMonitor *monitor;
 168
 169   monitor = G_FILE_MONITOR (object);
 170
 171   if (monitor->priv->timeout)
 172     {
 173       g_source_destroy (monitor->priv->timeout);
 174       g_source_unref (monitor->priv->timeout);
 175     }
 176
 177   g_hash_table_destroy (monitor->priv->rate_limiter);
 178
 179   g_main_context_unref (monitor->priv->context);
 180   g_mutex_clear (&monitor->priv->mutex);
 181
 182   G_OBJECT_CLASS (g_file_monitor_parent_class)->finalize (object);
 183 }
 184
 185 static void
 186 g_file_monitor_dispose (GObject *object)
 187 {
 188   GFileMonitor *monitor;
 189   GFileMonitorPrivate *priv;
 190
 191   monitor = G_FILE_MONITOR (object);
 192   priv = monitor->priv;
 193
 194   if (priv->pending_file_change_source)
 195     {
 196       g_source_destroy (priv->pending_file_change_source);
 197       g_source_unref (priv->pending_file_change_source);
 198       priv->pending_file_change_source = NULL;
 199     }
 200   g_slist_free_full (priv->pending_file_changes, (GDestroyNotify) file_change_free);
 201   priv->pending_file_changes = NULL;
 202
 203   /* Make sure we cancel on last unref */
 204   g_file_monitor_cancel (monitor);
 205
 206   G_OBJECT_CLASS (g_file_monitor_parent_class)->dispose (object);
 207 }
 208
 209 static void
 210 g_file_monitor_class_init (GFileMonitorClass *klass)
 211 {
 212   GObjectClass *object_class;
 213
 214   object_class = G_OBJECT_CLASS (klass);
 215   object_class->finalize = g_file_monitor_finalize;
 216   object_class->dispose = g_file_monitor_dispose;
 217   object_class->get_property = g_file_monitor_get_property;
 218   object_class->set_property = g_file_monitor_set_property;
 219
 220   /**
 221    * GFileMonitor::changed:
 222    * @monitor: a #GFileMonitor.
 223    * @file: a #GFile.
 224    * @other_file: (allow-none): a #GFile or #NULL.
 225    * @event_type: a #GFileMonitorEvent.
 226    *
 227    * Emitted when @file has been changed.
 228    *
 229    * If using #G_FILE_MONITOR_SEND_MOVED flag and @event_type is
 230    * #G_FILE_MONITOR_EVENT_MOVED, @file will be set to a #GFile containing the
 231    * old path, and @other_file will be set to a #GFile containing the new path.
 232    *
 233    * In all the other cases, @other_file will be set to #NULL.
 234    **/
 235   signals[CHANGED] =
 236     g_signal_new (I_("changed"),
 237                   G_TYPE_FILE_MONITOR,
 238                   G_SIGNAL_RUN_LAST,
 239                   G_STRUCT_OFFSET (GFileMonitorClass, changed),
 240                   NULL, NULL,
 241                   NULL,
 242                   G_TYPE_NONE, 3,
 243                   G_TYPE_FILE, G_TYPE_FILE, G_TYPE_FILE_MONITOR_EVENT);
 244
 245   g_object_class_install_property (object_class,
 246                                    PROP_RATE_LIMIT,
 247                                    g_param_spec_int ("rate-limit",
 248                                                      P_("Rate limit"),
 249                                                      P_("The limit of the monitor to watch for changes, in milliseconds"),
 250                                                      0, G_MAXINT,
 251                                                      DEFAULT_RATE_LIMIT_MSECS,
 252                                                      G_PARAM_READWRITE|
 253                                                      G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
 254
 255   g_object_class_install_property (object_class,
 256                                    PROP_CANCELLED,
 257                                    g_param_spec_boolean ("cancelled",
 258                                                          P_("Cancelled"),
 259                                                          P_("Whether the monitor has been cancelled"),
 260                                                          FALSE,
 261                                                          G_PARAM_READABLE|
 262                                                          G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
 263 }
 264
 265 static void
 266 g_file_monitor_init (GFileMonitor *monitor)
 267 {
 268   monitor->priv = g_file_monitor_get_private (monitor);
 269   monitor->priv->rate_limit_msec = DEFAULT_RATE_LIMIT_MSECS;
 270   monitor->priv->rate_limiter = g_hash_table_new_full (g_file_hash, (GEqualFunc)g_file_equal,
 271                                                        NULL, (GDestroyNotify) rate_limiter_free);
 272   monitor->priv->context = g_main_context_ref_thread_default ();
 273   g_mutex_init (&monitor->priv->mutex);
 274 }
 275
 276 /**
 277  * g_file_monitor_is_cancelled:
 278  * @monitor: a #GFileMonitor
 279  *
 280  * Returns whether the monitor is canceled.
 281  *
 282  * Returns: %TRUE if monitor is canceled. %FALSE otherwise.
 283  **/
 284 gboolean
 285 g_file_monitor_is_cancelled (GFileMonitor *monitor)
 286 {
 287   gboolean res;
 288
 289   g_return_val_if_fail (G_IS_FILE_MONITOR (monitor), FALSE);
 290
 291   G_LOCK (cancelled);
 292   res = monitor->priv->cancelled;
 293   G_UNLOCK (cancelled);
 294
 295   return res;
 296 }
 297
 298 /**
 299  * g_file_monitor_cancel:
 300  * @monitor: a #GFileMonitor.
 301  *
 302  * Cancels a file monitor.
 303  *
 304  * Returns: %TRUE if monitor was cancelled.
 305  **/
 306 gboolean
 307 g_file_monitor_cancel (GFileMonitor* monitor)
 308 {
 309   GFileMonitorClass *klass;
 310
 311   g_return_val_if_fail (G_IS_FILE_MONITOR (monitor), FALSE);
 312
 313   G_LOCK (cancelled);
 314   if (monitor->priv->cancelled)
 315     {
 316       G_UNLOCK (cancelled);
 317       return TRUE;
 318     }
 319
 320   monitor->priv->cancelled = TRUE;
 321   G_UNLOCK (cancelled);
 322
 323   g_object_notify (G_OBJECT (monitor), "cancelled");
 324
 325   klass = G_FILE_MONITOR_GET_CLASS (monitor);
 326   return (* klass->cancel) (monitor);
 327 }
 328
 329 /**
 330  * g_file_monitor_set_rate_limit:
 331  * @monitor: a #GFileMonitor.
 332  * @limit_msecs: a non-negative integer with the limit in milliseconds
 333  *     to poll for changes
 334  *
 335  * Sets the rate limit to which the @monitor will report
 336  * consecutive change events to the same file.
 337  */
 338 void
 339 g_file_monitor_set_rate_limit (GFileMonitor *monitor,
 340                                gint          limit_msecs)
 341 {
 342   GFileMonitorPrivate *priv;
 343
 344   g_return_if_fail (G_IS_FILE_MONITOR (monitor));
 345   g_return_if_fail (limit_msecs >= 0);
 346
 347   priv = monitor->priv;
 348   if (priv->rate_limit_msec != limit_msecs)
 349     {
 350       monitor->priv->rate_limit_msec = limit_msecs;
 351       g_object_notify (G_OBJECT (monitor), "rate-limit");
 352     }
 353 }
 354
 355 struct _FileChange {
 356   GFile             *child;
 357   GFile             *other_file;
 358   GFileMonitorEvent  event_type;
 359 };
 360
 361 static void
 362 file_change_free (FileChange *change)
 363 {
 364   g_object_unref (change->child);
 365   if (change->other_file)
 366     g_object_unref (change->other_file);
 367
 368   g_slice_free (FileChange, change);
 369 }
 370
 371 static gboolean
 372 emit_cb (gpointer data)
 373 {
 374   GFileMonitor *monitor = G_FILE_MONITOR (data);
 375   GSList *pending, *iter;
 376
 377   g_mutex_lock (&monitor->priv->mutex);
 378   pending = g_slist_reverse (monitor->priv->pending_file_changes);
 379   monitor->priv->pending_file_changes = NULL;
 380   if (monitor->priv->pending_file_change_source)
 381     {
 382       g_source_unref (monitor->priv->pending_file_change_source);
 383       monitor->priv->pending_file_change_source = NULL;
 384     }
 385   g_mutex_unlock (&monitor->priv->mutex);
 386
 387   g_object_ref (monitor);
 388   for (iter = pending; iter; iter = iter->next)
 389     {
 390        FileChange *change = iter->data;
 391
 392        g_signal_emit (monitor, signals[CHANGED], 0,
 393                       change->child, change->other_file, change->event_type);
 394        file_change_free (change);
 395     }
 396   g_slist_free (pending);
 397   g_object_unref (monitor);
 398
 399   return FALSE;
 400 }
 401
 402 static void
 403 emit_in_idle (GFileMonitor      *monitor,
 404               GFile             *child,
 405               GFile             *other_file,
 406               GFileMonitorEvent  event_type)
 407 {
 408   GSource *source;
 409   FileChange *change;
 410   GFileMonitorPrivate *priv;
 411
 412   priv = monitor->priv;
 413
 414   change = g_slice_new (FileChange);
 415
 416   change->child = g_object_ref (child);
 417   if (other_file)
 418     change->other_file = g_object_ref (other_file);
 419   else
 420     change->other_file = NULL;
 421   change->event_type = event_type;
 422
 423   g_mutex_lock (&monitor->priv->mutex);
 424   if (!priv->pending_file_change_source)
 425     {
 426       source = g_idle_source_new ();
 427       priv->pending_file_change_source = source;
 428       g_source_set_priority (source, 0);
 429
 430       /* We don't ref monitor here - instead dispose will free any
 431        * pending idles.
 432        */
 433       g_source_set_callback (source, emit_cb, monitor, NULL);
 434       g_source_attach (source, monitor->priv->context);
 435     }
 436   /* We reverse this in the processor */
 437   priv->pending_file_changes = g_slist_prepend (priv->pending_file_changes, change);
 438   g_mutex_unlock (&monitor->priv->mutex);
 439 }
 440
 441 static guint32
 442 get_time_msecs (void)
 443 {
 444   return g_get_monotonic_time () / G_TIME_SPAN_MILLISECOND;
 445 }
 446
 447 static guint32
 448 time_difference (guint32 from, guint32 to)
 449 {
 450   if (from > to)
 451     return 0;
 452   return to - from;
 453 }
 454
 455 /* Change event rate limiting support: */
 456
 457 static RateLimiter *
 458 new_limiter (GFileMonitor *monitor,
 459              GFile             *file)
 460 {
 461   RateLimiter *limiter;
 462
 463   limiter = g_slice_new0 (RateLimiter);
 464   limiter->file = g_object_ref (file);
 465   g_hash_table_insert (monitor->priv->rate_limiter, file, limiter);
 466
 467   return limiter;
 468 }
 469
 470 static void
 471 rate_limiter_send_virtual_changes_done_now (GFileMonitor *monitor,
 472                                             RateLimiter  *limiter)
 473 {
 474   if (limiter->send_virtual_changes_done_at != 0)
 475     {
 476       emit_in_idle (monitor, limiter->file, NULL,
 477                     G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT);
 478       limiter->send_virtual_changes_done_at = 0;
 479     }
 480 }
 481
 482 static void
 483 rate_limiter_send_delayed_change_now (GFileMonitor *monitor,
 484                                       RateLimiter *limiter,
 485                                       guint32 time_now)
 486 {
 487   if (limiter->send_delayed_change_at != 0)
 488     {
 489       emit_in_idle (monitor,
 490                     limiter->file, NULL,
 491                     G_FILE_MONITOR_EVENT_CHANGED);
 492       limiter->send_delayed_change_at = 0;
 493       limiter->last_sent_change_time = time_now;
 494     }
 495 }
 496
 497 typedef struct {
 498   guint32 min_time;
 499   guint32 time_now;
 500   GFileMonitor *monitor;
 501 } ForEachData;
 502
 503 static gboolean
 504 calc_min_time (GFileMonitor *monitor,
 505                RateLimiter *limiter,
 506                guint32 time_now,
 507                guint32 *min_time)
 508 {
 509   gboolean delete_me;
 510   guint32 expire_at;
 511
 512   delete_me = TRUE;
 513
 514   if (limiter->last_sent_change_time != 0)
 515     {
 516       /* Set a timeout at 2*rate limit so that we can clear out the change from the hash eventually */
 517       expire_at = limiter->last_sent_change_time + 2 * monitor->priv->rate_limit_msec;
 518
 519       if (time_difference (time_now, expire_at) > 0)
 520         {
 521           delete_me = FALSE;
 522           *min_time = MIN (*min_time,
 523                            time_difference (time_now, expire_at));
 524         }
 525     }
 526
 527   if (limiter->send_delayed_change_at != 0)
 528     {
 529       delete_me = FALSE;
 530       *min_time = MIN (*min_time,
 531                        time_difference (time_now, limiter->send_delayed_change_at));
 532     }
 533
 534   if (limiter->send_virtual_changes_done_at != 0)
 535     {
 536       delete_me = FALSE;
 537       *min_time = MIN (*min_time,
 538                        time_difference (time_now, limiter->send_virtual_changes_done_at));
 539     }
 540
 541   return delete_me;
 542 }
 543
 544 static gboolean
 545 foreach_rate_limiter_fire (gpointer key,
 546                            gpointer value,
 547                            gpointer user_data)
 548 {
 549   RateLimiter *limiter = value;
 550   ForEachData *data = user_data;
 551
 552   if (limiter->send_delayed_change_at != 0 &&
 553       time_difference (data->time_now, limiter->send_delayed_change_at) == 0)
 554     rate_limiter_send_delayed_change_now (data->monitor, limiter, data->time_now);
 555
 556   if (limiter->send_virtual_changes_done_at != 0 &&
 557       time_difference (data->time_now, limiter->send_virtual_changes_done_at) == 0)
 558     rate_limiter_send_virtual_changes_done_now (data->monitor, limiter);
 559
 560   return calc_min_time (data->monitor, limiter, data->time_now, &data->min_time);
 561 }
 562
 563 static gboolean
 564 rate_limiter_timeout (gpointer timeout_data)
 565 {
 566   GFileMonitor *monitor = timeout_data;
 567   ForEachData data;
 568   GSource *source;
 569
 570   data.min_time = G_MAXUINT32;
 571   data.monitor = monitor;
 572   data.time_now = get_time_msecs ();
 573   g_hash_table_foreach_remove (monitor->priv->rate_limiter,
 574                                foreach_rate_limiter_fire,
 575                                &data);
 576
 577   /* Remove old timeout */
 578   if (monitor->priv->timeout)
 579     {
 580       g_source_destroy (monitor->priv->timeout);
 581       g_source_unref (monitor->priv->timeout);
 582       monitor->priv->timeout = NULL;
 583       monitor->priv->timeout_fires_at = 0;
 584     }
 585
 586   /* Set up new timeout */
 587   if (data.min_time != G_MAXUINT32)
 588     {
 589       source = g_timeout_source_new (data.min_time + 1); /* + 1 to make sure we've really passed the time */
 590       g_source_set_callback (source, rate_limiter_timeout, monitor, NULL);
 591       g_source_attach (source, monitor->priv->context);
 592
 593       monitor->priv->timeout = source;
 594       monitor->priv->timeout_fires_at = data.time_now + data.min_time;
 595     }
 596
 597   return FALSE;
 598 }
 599
 600 static gboolean
 601 foreach_rate_limiter_update (gpointer key,
 602                              gpointer value,
 603                              gpointer user_data)
 604 {
 605   RateLimiter *limiter = value;
 606   ForEachData *data = user_data;
 607
 608   return calc_min_time (data->monitor, limiter, data->time_now, &data->min_time);
 609 }
 610
 611 static void
 612 update_rate_limiter_timeout (GFileMonitor *monitor,
 613                              guint new_time)
 614 {
 615   ForEachData data;
 616   GSource *source;
 617
 618   if (monitor->priv->timeout_fires_at != 0 && new_time != 0 &&
 619       time_difference (new_time, monitor->priv->timeout_fires_at) == 0)
 620     return; /* Nothing to do, we already fire earlier than that */
 621
 622   data.min_time = G_MAXUINT32;
 623   data.monitor = monitor;
 624   data.time_now = get_time_msecs ();
 625   g_hash_table_foreach_remove (monitor->priv->rate_limiter,
 626                                foreach_rate_limiter_update,
 627                                &data);
 628
 629   /* Remove old timeout */
 630   if (monitor->priv->timeout)
 631     {
 632       g_source_destroy (monitor->priv->timeout);
 633       g_source_unref (monitor->priv->timeout);
 634       monitor->priv->timeout_fires_at = 0;
 635       monitor->priv->timeout = NULL;
 636     }
 637
 638   /* Set up new timeout */
 639   if (data.min_time != G_MAXUINT32)
 640     {
 641       source = g_timeout_source_new (data.min_time + 1);  /* + 1 to make sure we've really passed the time */
 642       g_source_set_callback (source, rate_limiter_timeout, monitor, NULL);
 643       g_source_attach (source, monitor->priv->context);
 644
 645       monitor->priv->timeout = source;
 646       monitor->priv->timeout_fires_at = data.time_now + data.min_time;
 647     }
 648 }
 649
 650 /**
 651  * g_file_monitor_emit_event:
 652  * @monitor: a #GFileMonitor.
 653  * @child: a #GFile.
 654  * @other_file: a #GFile.
 655  * @event_type: a set of #GFileMonitorEvent flags.
 656  *
 657  * Emits the #GFileMonitor::changed signal if a change
 658  * has taken place. Should be called from file monitor
 659  * implementations only.
 660  *
 661  * The signal will be emitted from an idle handler (in the <link
 662  * linkend="g-main-context-push-thread-default">thread-default main
 663  * context</link>).
 664  **/
 665 void
 666 g_file_monitor_emit_event (GFileMonitor      *monitor,
 667                            GFile             *child,
 668                            GFile             *other_file,
 669                            GFileMonitorEvent  event_type)
 670 {
 671   guint32 time_now, since_last;
 672   gboolean emit_now;
 673   RateLimiter *limiter;
 674
 675   g_return_if_fail (G_IS_FILE_MONITOR (monitor));
 676   g_return_if_fail (G_IS_FILE (child));
 677
 678   limiter = g_hash_table_lookup (monitor->priv->rate_limiter, child);
 679
 680   if (event_type != G_FILE_MONITOR_EVENT_CHANGED)
 681     {
 682       if (limiter)
 683         {
 684           rate_limiter_send_delayed_change_now (monitor, limiter, get_time_msecs ());
 685           if (event_type == G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT)
 686             limiter->send_virtual_changes_done_at = 0;
 687           else
 688             rate_limiter_send_virtual_changes_done_now (monitor, limiter);
 689           update_rate_limiter_timeout (monitor, 0);
 690         }
 691       emit_in_idle (monitor, child, other_file, event_type);
 692     }
 693   else
 694     {
 695       /* Changed event, rate limit */
 696       time_now = get_time_msecs ();
 697       emit_now = TRUE;
 698
 699       if (limiter)
 700         {
 701           since_last = time_difference (limiter->last_sent_change_time, time_now);
 702           if (since_last < monitor->priv->rate_limit_msec)
 703             {
 704               /* We ignore this change, but arm a timer so that we can fire it later if we
 705                  don't get any other events (that kill this timeout) */
 706               emit_now = FALSE;
 707               if (limiter->send_delayed_change_at == 0)
 708                 {
 709                   limiter->send_delayed_change_at = time_now + monitor->priv->rate_limit_msec;
 710                   update_rate_limiter_timeout (monitor, limiter->send_delayed_change_at);
 711                 }
 712             }
 713         }
 714
 715       if (limiter == NULL)
 716         limiter = new_limiter (monitor, child);
 717
 718       if (emit_now)
 719         {
 720           emit_in_idle (monitor, child, other_file, event_type);
 721
 722           limiter->last_sent_change_time = time_now;
 723           limiter->send_delayed_change_at = 0;
 724           /* Set a timeout of 2*rate limit so that we can clear out the change from the hash eventually */
 725           update_rate_limiter_timeout (monitor, time_now + 2 * monitor->priv->rate_limit_msec);
 726         }
 727
 728       /* Schedule a virtual change done. This is removed if we get a real one, and
 729          postponed if we get more change events. */
 730
 731       limiter->send_virtual_changes_done_at = time_now + DEFAULT_VIRTUAL_CHANGES_DONE_DELAY_SECS * 1000;
 732       update_rate_limiter_timeout (monitor, limiter->send_virtual_changes_done_at);
 733     }
 734 }