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