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