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