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 "gio-marshal.h"
  28 #include "gioenumtypes.h"
  29 #include "gvfs.h"
  30 #include "glibintl.h"
  31
  32 #include "gioalias.h"
  33
  34 /**
  35  * SECTION:gfilemonitor
  36  * @short_description: File Monitor
  37  * @include: gio/gio.h
  38  *
  39  * Monitors a file or directory for changes.
  40  *
  41  * To obtain a #GFileMonitor for a file or directory, use
  42  * g_file_monitor_file() or g_file_monitor_directory().
  43  *
  44  * To get informed about changes to the file or directory you
  45  * are monitoring, connect to the #GFileMonitor::changed signal.
  46  **/
  47
  48 G_LOCK_DEFINE_STATIC(cancelled);
  49
  50 enum {
  51   CHANGED,
  52   LAST_SIGNAL
  53 };
  54
  55 G_DEFINE_ABSTRACT_TYPE (GFileMonitor, g_file_monitor, G_TYPE_OBJECT);
  56
  57 typedef struct {
  58   GFile *file;
  59   guint32 last_sent_change_time; /* 0 == not sent */
  60   guint32 send_delayed_change_at; /* 0 == never */
  61   guint32 send_virtual_changes_done_at; /* 0 == never */
  62 } RateLimiter;
  63
  64 struct _GFileMonitorPrivate {
  65   gboolean cancelled;
  66   int rate_limit_msec;
  67
  68   /* Rate limiting change events */
  69   GHashTable *rate_limiter;
  70
  71   GSource *timeout;
  72   guint32 timeout_fires_at;
  73 };
  74
  75 enum {
  76   PROP_0,
  77   PROP_RATE_LIMIT,
  78   PROP_CANCELLED
  79 };
  80
  81 static void
  82 g_file_monitor_set_property (GObject      *object,
  83                              guint         prop_id,
  84                              const GValue *value,
  85                              GParamSpec   *pspec)
  86 {
  87   GFileMonitor *monitor;
  88
  89   monitor = G_FILE_MONITOR (object);
  90
  91   switch (prop_id)
  92     {
  93     case PROP_RATE_LIMIT:
  94       g_file_monitor_set_rate_limit (monitor, g_value_get_int (value));
  95       break;
  96
  97     default:
  98       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
  99       break;
 100     }
 101 }
 102
 103 static void
 104 g_file_monitor_get_property (GObject    *object,
 105                              guint       prop_id,
 106                              GValue     *value,
 107                              GParamSpec *pspec)
 108 {
 109   GFileMonitor *monitor;
 110   GFileMonitorPrivate *priv;
 111
 112   monitor = G_FILE_MONITOR (object);
 113   priv = monitor->priv;
 114
 115   switch (prop_id)
 116     {
 117     case PROP_RATE_LIMIT:
 118       g_value_set_int (value, priv->rate_limit_msec);
 119       break;
 120
 121     case PROP_CANCELLED:
 122       G_LOCK (cancelled);
 123       g_value_set_boolean (value, priv->cancelled);
 124       G_UNLOCK (cancelled);
 125       break;
 126
 127     default:
 128       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
 129       break;
 130     }
 131 }
 132
 133 #define DEFAULT_RATE_LIMIT_MSECS 800
 134 #define DEFAULT_VIRTUAL_CHANGES_DONE_DELAY_SECS 2
 135
 136 static guint signals[LAST_SIGNAL] = { 0 };
 137
 138 static void
 139 rate_limiter_free (RateLimiter *limiter)
 140 {
 141   g_object_unref (limiter->file);
 142   g_slice_free (RateLimiter, limiter);
 143 }
 144
 145 static void
 146 g_file_monitor_finalize (GObject *object)
 147 {
 148   GFileMonitor *monitor;
 149
 150   monitor = G_FILE_MONITOR (object);
 151
 152   if (monitor->priv->timeout)
 153     {
 154       g_source_destroy (monitor->priv->timeout);
 155       g_source_unref (monitor->priv->timeout);
 156     }
 157
 158   g_hash_table_destroy (monitor->priv->rate_limiter);
 159
 160   if (G_OBJECT_CLASS (g_file_monitor_parent_class)->finalize)
 161     (*G_OBJECT_CLASS (g_file_monitor_parent_class)->finalize) (object);
 162 }
 163
 164 static void
 165 g_file_monitor_dispose (GObject *object)
 166 {
 167   GFileMonitor *monitor;
 168
 169   monitor = G_FILE_MONITOR (object);
 170
 171   /* Make sure we cancel on last unref */
 172   g_file_monitor_cancel (monitor);
 173
 174   if (G_OBJECT_CLASS (g_file_monitor_parent_class)->dispose)
 175     (*G_OBJECT_CLASS (g_file_monitor_parent_class)->dispose) (object);
 176 }
 177
 178 static void
 179 g_file_monitor_class_init (GFileMonitorClass *klass)
 180 {
 181   GObjectClass *object_class;
 182
 183   g_type_class_add_private (klass, sizeof (GFileMonitorPrivate));
 184
 185   object_class = G_OBJECT_CLASS (klass);
 186   object_class->finalize = g_file_monitor_finalize;
 187   object_class->dispose = g_file_monitor_dispose;
 188   object_class->get_property = g_file_monitor_get_property;
 189   object_class->set_property = g_file_monitor_set_property;
 190
 191   /**
 192    * GFileMonitor::changed:
 193    * @monitor: a #GFileMonitor.
 194    * @file: a #GFile.
 195    * @other_file: a #GFile.
 196    * @event_type: a #GFileMonitorEvent.
 197    *
 198    * Emitted when a file has been changed.
 199    **/
 200   signals[CHANGED] =
 201     g_signal_new (I_("changed"),
 202                   G_TYPE_FILE_MONITOR,
 203                   G_SIGNAL_RUN_LAST,
 204                   G_STRUCT_OFFSET (GFileMonitorClass, changed),
 205                   NULL, NULL,
 206                   _gio_marshal_VOID__OBJECT_OBJECT_ENUM,
 207                   G_TYPE_NONE, 3,
 208                   G_TYPE_FILE, G_TYPE_FILE, G_TYPE_FILE_MONITOR_EVENT);
 209
 210   g_object_class_install_property (object_class,
 211                                    PROP_RATE_LIMIT,
 212                                    g_param_spec_int ("rate-limit",
 213                                                      P_("Rate limit"),
 214                                                      P_("The limit of the monitor to watch for changes, in milliseconds"),
 215                                                      0, G_MAXINT,
 216                                                      DEFAULT_RATE_LIMIT_MSECS,
 217                                                      G_PARAM_READWRITE|
 218                                                      G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
 219
 220   g_object_class_install_property (object_class,
 221                                    PROP_CANCELLED,
 222                                    g_param_spec_boolean ("cancelled",
 223                                                          P_("Cancelled"),
 224                                                          P_("Whether the monitor has been cancelled"),
 225                                                          FALSE,
 226                                                          G_PARAM_READABLE|
 227                                                          G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
 228 }
 229
 230 static void
 231 g_file_monitor_init (GFileMonitor *monitor)
 232 {
 233   monitor->priv = G_TYPE_INSTANCE_GET_PRIVATE (monitor,
 234                                                G_TYPE_FILE_MONITOR,
 235                                                GFileMonitorPrivate);
 236   monitor->priv->rate_limit_msec = DEFAULT_RATE_LIMIT_MSECS;
 237   monitor->priv->rate_limiter = g_hash_table_new_full (g_file_hash, (GEqualFunc)g_file_equal,
 238                                                        NULL, (GDestroyNotify) rate_limiter_free);
 239 }
 240
 241 /**
 242  * g_file_monitor_is_cancelled:
 243  * @monitor: a #GFileMonitor
 244  *
 245  * Returns whether the monitor is canceled.
 246  *
 247  * Returns: %TRUE if monitor is canceled. %FALSE otherwise.
 248  **/
 249 gboolean
 250 g_file_monitor_is_cancelled (GFileMonitor *monitor)
 251 {
 252   gboolean res;
 253
 254   g_return_val_if_fail (G_IS_FILE_MONITOR (monitor), FALSE);
 255
 256   G_LOCK (cancelled);
 257   res = monitor->priv->cancelled;
 258   G_UNLOCK (cancelled);
 259
 260   return res;
 261 }
 262
 263 /**
 264  * g_file_monitor_cancel:
 265  * @monitor: a #GFileMonitor.
 266  *
 267  * Cancels a file monitor.
 268  *
 269  * Returns: %TRUE if monitor was cancelled.
 270  **/
 271 gboolean
 272 g_file_monitor_cancel (GFileMonitor* monitor)
 273 {
 274   GFileMonitorClass *klass;
 275
 276   g_return_val_if_fail (G_IS_FILE_MONITOR (monitor), FALSE);
 277
 278   G_LOCK (cancelled);
 279   if (monitor->priv->cancelled)
 280     {
 281       G_UNLOCK (cancelled);
 282       return TRUE;
 283     }
 284
 285   monitor->priv->cancelled = TRUE;
 286   G_UNLOCK (cancelled);
 287
 288   g_object_notify (G_OBJECT (monitor), "cancelled");
 289
 290   klass = G_FILE_MONITOR_GET_CLASS (monitor);
 291   return (* klass->cancel) (monitor);
 292 }
 293
 294 /**
 295  * g_file_monitor_set_rate_limit:
 296  * @monitor: a #GFileMonitor.
 297  * @limit_msecs: a integer with the limit in milliseconds to
 298  * poll for changes.
 299  *
 300  * Sets the rate limit to which the @monitor will report
 301  * consecutive change events to the same file.
 302  *
 303  **/
 304 void
 305 g_file_monitor_set_rate_limit (GFileMonitor *monitor,
 306                                int           limit_msecs)
 307 {
 308   GFileMonitorPrivate *priv;
 309
 310   g_return_if_fail (G_IS_FILE_MONITOR (monitor));
 311
 312   priv = monitor->priv;
 313   if (priv->rate_limit_msec != limit_msecs)
 314     {
 315       monitor->priv->rate_limit_msec = limit_msecs;
 316       g_object_notify (G_OBJECT (monitor), "rate-limit");
 317     }
 318 }
 319
 320 typedef struct {
 321   GFileMonitor      *monitor;
 322   GFile             *child;
 323   GFile             *other_file;
 324   GFileMonitorEvent  event_type;
 325 } FileChange;
 326
 327 static gboolean
 328 emit_cb (gpointer data)
 329 {
 330   FileChange *change = data;
 331   g_signal_emit (change->monitor, signals[CHANGED], 0,
 332                  change->child, change->other_file, change->event_type);
 333   return FALSE;
 334 }
 335
 336 static void
 337 file_change_free (FileChange *change)
 338 {
 339   g_object_unref (change->monitor);
 340   g_object_unref (change->child);
 341   if (change->other_file)
 342     g_object_unref (change->other_file);
 343
 344   g_slice_free (FileChange, change);
 345 }
 346
 347 static void
 348 emit_in_idle (GFileMonitor      *monitor,
 349               GFile             *child,
 350               GFile             *other_file,
 351               GFileMonitorEvent  event_type)
 352 {
 353   GSource *source;
 354   FileChange *change;
 355
 356   change = g_slice_new (FileChange);
 357
 358   change->monitor = g_object_ref (monitor);
 359   change->child = g_object_ref (child);
 360   if (other_file)
 361     change->other_file = g_object_ref (other_file);
 362   else
 363     change->other_file = NULL;
 364   change->event_type = event_type;
 365
 366   source = g_idle_source_new ();
 367   g_source_set_priority (source, 0);
 368
 369   g_source_set_callback (source, emit_cb, change, (GDestroyNotify)file_change_free);
 370   g_source_attach (source, NULL);
 371   g_source_unref (source);
 372 }
 373
 374 static guint32
 375 get_time_msecs (void)
 376 {
 377   return g_thread_gettime() / (1000 * 1000);
 378 }
 379
 380 static guint32
 381 time_difference (guint32 from, guint32 to)
 382 {
 383   if (from > to)
 384     return 0;
 385   return to - from;
 386 }
 387
 388 /* Change event rate limiting support: */
 389
 390 static RateLimiter *
 391 new_limiter (GFileMonitor *monitor,
 392              GFile             *file)
 393 {
 394   RateLimiter *limiter;
 395
 396   limiter = g_slice_new0 (RateLimiter);
 397   limiter->file = g_object_ref (file);
 398   g_hash_table_insert (monitor->priv->rate_limiter, file, limiter);
 399
 400   return limiter;
 401 }
 402
 403 static void
 404 rate_limiter_send_virtual_changes_done_now (GFileMonitor *monitor,
 405                                             RateLimiter  *limiter)
 406 {
 407   if (limiter->send_virtual_changes_done_at != 0)
 408     {
 409       emit_in_idle (monitor, limiter->file, NULL,
 410                     G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT);
 411       limiter->send_virtual_changes_done_at = 0;
 412     }
 413 }
 414
 415 static void
 416 rate_limiter_send_delayed_change_now (GFileMonitor *monitor,
 417                                       RateLimiter *limiter,
 418                                       guint32 time_now)
 419 {
 420   if (limiter->send_delayed_change_at != 0)
 421     {
 422       emit_in_idle (monitor,
 423                     limiter->file, NULL,
 424                     G_FILE_MONITOR_EVENT_CHANGED);
 425       limiter->send_delayed_change_at = 0;
 426       limiter->last_sent_change_time = time_now;
 427     }
 428 }
 429
 430 typedef struct {
 431   guint32 min_time;
 432   guint32 time_now;
 433   GFileMonitor *monitor;
 434 } ForEachData;
 435
 436 static gboolean
 437 calc_min_time (GFileMonitor *monitor,
 438                RateLimiter *limiter,
 439                guint32 time_now,
 440                guint32 *min_time)
 441 {
 442   gboolean delete_me;
 443   guint32 expire_at;
 444
 445   delete_me = TRUE;
 446
 447   if (limiter->last_sent_change_time != 0)
 448     {
 449       /* Set a timeout at 2*rate limit so that we can clear out the change from the hash eventualy */
 450       expire_at = limiter->last_sent_change_time + 2 * monitor->priv->rate_limit_msec;
 451
 452       if (time_difference (time_now, expire_at) > 0)
 453         {
 454           delete_me = FALSE;
 455           *min_time = MIN (*min_time,
 456                            time_difference (time_now, expire_at));
 457         }
 458     }
 459
 460   if (limiter->send_delayed_change_at != 0)
 461     {
 462       delete_me = FALSE;
 463       *min_time = MIN (*min_time,
 464                        time_difference (time_now, limiter->send_delayed_change_at));
 465     }
 466
 467   if (limiter->send_virtual_changes_done_at != 0)
 468     {
 469       delete_me = FALSE;
 470       *min_time = MIN (*min_time,
 471                        time_difference (time_now, limiter->send_virtual_changes_done_at));
 472     }
 473
 474   return delete_me;
 475 }
 476
 477 static gboolean
 478 foreach_rate_limiter_fire (gpointer key,
 479                            gpointer value,
 480                            gpointer user_data)
 481 {
 482   RateLimiter *limiter = value;
 483   ForEachData *data = user_data;
 484
 485   if (limiter->send_delayed_change_at != 0 &&
 486       time_difference (data->time_now, limiter->send_delayed_change_at) == 0)
 487     rate_limiter_send_delayed_change_now (data->monitor, limiter, data->time_now);
 488
 489   if (limiter->send_virtual_changes_done_at != 0 &&
 490       time_difference (data->time_now, limiter->send_virtual_changes_done_at) == 0)
 491     rate_limiter_send_virtual_changes_done_now (data->monitor, limiter);
 492
 493   return calc_min_time (data->monitor, limiter, data->time_now, &data->min_time);
 494 }
 495
 496 static gboolean
 497 rate_limiter_timeout (gpointer timeout_data)
 498 {
 499   GFileMonitor *monitor = timeout_data;
 500   ForEachData data;
 501   GSource *source;
 502
 503   data.min_time = G_MAXUINT32;
 504   data.monitor = monitor;
 505   data.time_now = get_time_msecs ();
 506   g_hash_table_foreach_remove (monitor->priv->rate_limiter,
 507                                foreach_rate_limiter_fire,
 508                                &data);
 509
 510   /* Remove old timeout */
 511   if (monitor->priv->timeout)
 512     {
 513       g_source_destroy (monitor->priv->timeout);
 514       g_source_unref (monitor->priv->timeout);
 515       monitor->priv->timeout = NULL;
 516       monitor->priv->timeout_fires_at = 0;
 517     }
 518
 519   /* Set up new timeout */
 520   if (data.min_time != G_MAXUINT32)
 521     {
 522       source = g_timeout_source_new (data.min_time + 1); /* + 1 to make sure we've really passed the time */
 523       g_source_set_callback (source, rate_limiter_timeout, monitor, NULL);
 524       g_source_attach (source, NULL);
 525
 526       monitor->priv->timeout = source;
 527       monitor->priv->timeout_fires_at = data.time_now + data.min_time;
 528     }
 529
 530   return FALSE;
 531 }
 532
 533 static gboolean
 534 foreach_rate_limiter_update (gpointer key,
 535                              gpointer value,
 536                              gpointer user_data)
 537 {
 538   RateLimiter *limiter = value;
 539   ForEachData *data = user_data;
 540
 541   return calc_min_time (data->monitor, limiter, data->time_now, &data->min_time);
 542 }
 543
 544 static void
 545 update_rate_limiter_timeout (GFileMonitor *monitor,
 546                              guint new_time)
 547 {
 548   ForEachData data;
 549   GSource *source;
 550
 551   if (monitor->priv->timeout_fires_at != 0 && new_time != 0 &&
 552       time_difference (new_time, monitor->priv->timeout_fires_at) == 0)
 553     return; /* Nothing to do, we already fire earlier than that */
 554
 555   data.min_time = G_MAXUINT32;
 556   data.monitor = monitor;
 557   data.time_now = get_time_msecs ();
 558   g_hash_table_foreach_remove (monitor->priv->rate_limiter,
 559                                foreach_rate_limiter_update,
 560                                &data);
 561
 562   /* Remove old timeout */
 563   if (monitor->priv->timeout)
 564     {
 565       g_source_destroy (monitor->priv->timeout);
 566       g_source_unref (monitor->priv->timeout);
 567       monitor->priv->timeout_fires_at = 0;
 568       monitor->priv->timeout = NULL;
 569     }
 570
 571   /* Set up new timeout */
 572   if (data.min_time != G_MAXUINT32)
 573     {
 574       source = g_timeout_source_new (data.min_time + 1);  /* + 1 to make sure we've really passed the time */
 575       g_source_set_callback (source, rate_limiter_timeout, monitor, NULL);
 576       g_source_attach (source, NULL);
 577
 578       monitor->priv->timeout = source;
 579       monitor->priv->timeout_fires_at = data.time_now + data.min_time;
 580     }
 581 }
 582
 583 /**
 584  * g_file_monitor_emit_event:
 585  * @monitor: a #GFileMonitor.
 586  * @child: a #GFile.
 587  * @other_file: a #GFile.
 588  * @event_type: a set of #GFileMonitorEvent flags.
 589  *
 590  * Emits the #GFileMonitor::changed signal if a change
 591  * has taken place. Should be called from file monitor
 592  * implementations only.
 593  *
 594  * The signal will be emitted from an idle handler.
 595  **/
 596 void
 597 g_file_monitor_emit_event (GFileMonitor      *monitor,
 598                            GFile             *child,
 599                            GFile             *other_file,
 600                            GFileMonitorEvent  event_type)
 601 {
 602   guint32 time_now, since_last;
 603   gboolean emit_now;
 604   RateLimiter *limiter;
 605
 606   g_return_if_fail (G_IS_FILE_MONITOR (monitor));
 607   g_return_if_fail (G_IS_FILE (child));
 608
 609   limiter = g_hash_table_lookup (monitor->priv->rate_limiter, child);
 610
 611   if (event_type != G_FILE_MONITOR_EVENT_CHANGED)
 612     {
 613       if (limiter)
 614         {
 615           rate_limiter_send_delayed_change_now (monitor, limiter, get_time_msecs ());
 616           if (event_type == G_FILE_MONITOR_EVENT_CHANGES_DONE_HINT)
 617             limiter->send_virtual_changes_done_at = 0;
 618           else
 619             rate_limiter_send_virtual_changes_done_now (monitor, limiter);
 620           update_rate_limiter_timeout (monitor, 0);
 621         }
 622       emit_in_idle (monitor, child, other_file, event_type);
 623     }
 624   else
 625     {
 626       /* Changed event, rate limit */
 627       time_now = get_time_msecs ();
 628       emit_now = TRUE;
 629
 630       if (limiter)
 631         {
 632           since_last = time_difference (limiter->last_sent_change_time, time_now);
 633           if (since_last < monitor->priv->rate_limit_msec)
 634             {
 635               /* We ignore this change, but arm a timer so that we can fire it later if we
 636                  don't get any other events (that kill this timeout) */
 637               emit_now = FALSE;
 638               if (limiter->send_delayed_change_at == 0)
 639                 {
 640                   limiter->send_delayed_change_at = time_now + monitor->priv->rate_limit_msec;
 641                   update_rate_limiter_timeout (monitor, limiter->send_delayed_change_at);
 642                 }
 643             }
 644         }
 645
 646       if (limiter == NULL)
 647         limiter = new_limiter (monitor, child);
 648
 649       if (emit_now)
 650         {
 651           emit_in_idle (monitor, child, other_file, event_type);
 652
 653           limiter->last_sent_change_time = time_now;
 654           limiter->send_delayed_change_at = 0;
 655           /* Set a timeout of 2*rate limit so that we can clear out the change from the hash eventualy */
 656           update_rate_limiter_timeout (monitor, time_now + 2 * monitor->priv->rate_limit_msec);
 657         }
 658
 659       /* Schedule a virtual change done. This is removed if we get a real one, and
 660          postponed if we get more change events. */
 661
 662       limiter->send_virtual_changes_done_at = time_now + DEFAULT_VIRTUAL_CHANGES_DONE_DELAY_SECS * 1000;
 663       update_rate_limiter_timeout (monitor, limiter->send_virtual_changes_done_at);
 664     }
 665 }
 666
 667 #define __G_FILE_MONITOR_C__
 668 #include "gioaliasdef.c"