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