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