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