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