inotify-kernel.c

this is a glib for c language

  
  if (is_dir)
    {
      switch (mask)
	{
	case IN_ACCESS:
	  return "ACCESS (dir)";
	case IN_MODIFY:
	  return "MODIFY (dir)";
	case IN_ATTRIB:
	  return "ATTRIB (dir)";
	case IN_CLOSE_WRITE:
	  return "CLOSE_WRITE (dir)";
	case IN_CLOSE_NOWRITE:
	  return "CLOSE_NOWRITE (dir)"; 
	case IN_OPEN:
	  return "OPEN (dir)";
	case IN_MOVED_FROM:
	  return "MOVED_FROM (dir)";
	case IN_MOVED_TO:
	  return "MOVED_TO (dir)";
	case IN_DELETE:
	  return "DELETE (dir)";
	case IN_CREATE:
	  return "CREATE (dir)";
	case IN_DELETE_SELF:
	  return "DELETE_SELF (dir)";
	case IN_UNMOUNT:
	  return "UNMOUNT (dir)";
	case IN_Q_OVERFLOW:
	  return "Q_OVERFLOW (dir)";
	case IN_IGNORED:
	  return "IGNORED (dir)";
	default:
	  return "UNKNOWN_EVENT (dir)";
	}
    }
  else
    {
      switch (mask)
	{
	case IN_ACCESS:
	  return "ACCESS";
	case IN_MODIFY:
	  return "MODIFY";
	case IN_ATTRIB:
	  return "ATTRIB";
	case IN_CLOSE_WRITE:
	  return "CLOSE_WRITE";
	case IN_CLOSE_NOWRITE:
	  return "CLOSE_NOWRITE";
	case IN_OPEN:
	  return "OPEN";
	case IN_MOVED_FROM:
	  return "MOVED_FROM";
	case IN_MOVED_TO:
	  return "MOVED_TO";
	case IN_DELETE:
	  return "DELETE";
	case IN_CREATE:
	  return "CREATE";
	case IN_DELETE_SELF:
	  return "DELETE_SELF";
	case IN_UNMOUNT:
	  return "UNMOUNT";
	case IN_Q_OVERFLOW:
	  return "Q_OVERFLOW";
	case IN_IGNORED:
	  return "IGNORED";
	default:
	  return "UNKNOWN_EVENT";
	}
    }
}


static void
ik_read_events (gsize  *buffer_size_out, 
                gchar **buffer_out)
{
  static gchar *buffer = NULL;
  static gsize buffer_size;
  
  /* Initialize the buffer on our first call */
  if (buffer == NULL)
    {
      buffer_size = AVERAGE_EVENT_SIZE;
      buffer_size *= MAX_QUEUED_EVENTS;
      buffer = g_malloc (buffer_size);
    }

  *buffer_size_out = 0;
  *buffer_out = NULL;
  
  memset (buffer, 0, buffer_size);

  if (g_io_channel_read_chars (inotify_read_ioc, (char *)buffer, buffer_size, buffer_size_out, NULL) != G_IO_STATUS_NORMAL) {
    /* error reading */
  }
  *buffer_out = buffer;
}

static gboolean
ik_read_callback (gpointer user_data)
{
  gchar *buffer;
  gsize buffer_size, buffer_i, events;
  
  G_LOCK (inotify_lock);
  ik_read_events (&buffer_size, &buffer);
  
  buffer_i = 0;
  events = 0;
  while (buffer_i < buffer_size)
    {
      struct inotify_event *event;
      gsize event_size;
      event = (struct inotify_event *)&buffer[buffer_i];
      event_size = sizeof(struct inotify_event) + event->len;
      g_queue_push_tail (events_to_process, ik_event_internal_new (ik_event_new (&buffer[buffer_i])));
      buffer_i += event_size;
      events++;
    }
  
  /* If the event process callback is off, turn it back on */
  if (!process_eq_running && events)
    {
      process_eq_running = TRUE;
      g_timeout_add (PROCESS_EVENTS_TIME, ik_process_eq_callback, NULL);
    }
  
  G_UNLOCK (inotify_lock);
  
  return TRUE;
}

static gboolean
g_timeval_lt (GTimeVal *val1, 
              GTimeVal *val2)
{
  if (val1->tv_sec < val2->tv_sec)
    return TRUE;
  
  if (val1->tv_sec > val2->tv_sec)
    return FALSE;
  
  /* val1->tv_sec == val2->tv_sec */
  if (val1->tv_usec < val2->tv_usec)
    return TRUE;
  
  return FALSE;
}

static gboolean
g_timeval_eq (GTimeVal *val1, 
              GTimeVal *val2)
{
  return (val1->tv_sec == val2->tv_sec) && (val1->tv_usec == val2->tv_usec);
}

static void
ik_pair_events (ik_event_internal_t *event1, 
                ik_event_internal_t *event2)
{
  g_assert (event1 && event2);
  /* We should only be pairing events that have the same cookie */
  g_assert (event1->event->cookie == event2->event->cookie);
  /* We shouldn't pair an event that already is paired */
  g_assert (event1->pair == NULL && event2->pair == NULL);
  
  /* Pair the internal structures and the ik_event_t structures */
  event1->pair = event2;
  event1->event->pair = event2->event;
  
  if (g_timeval_lt (&event1->hold_until, &event2->hold_until))
    event1->hold_until = event2->hold_until;
  
  event2->hold_until = event1->hold_until;
}

static void
ik_event_add_microseconds (ik_event_internal_t *event, 
                           glong                ms)
{
  g_assert (event);
  g_time_val_add (&event->hold_until, ms);
}

static gboolean
ik_event_ready (ik_event_internal_t *event)
{
  GTimeVal tv;
  g_assert (event);
  
  g_get_current_time (&tv);
  
  /* An event is ready if,
   *
   * it has no cookie -- there is nothing to be gained by holding it
   * or, it is already paired -- we don't need to hold it anymore
   * or, we have held it long enough
   */
  return
    event->event->cookie == 0 ||
    event->pair != NULL ||
    g_timeval_lt (&event->hold_until, &tv) ||
    g_timeval_eq (&event->hold_until, &tv);
}

static void
ik_pair_moves (gpointer data, 
               gpointer user_data)
{
  ik_event_internal_t *event = (ik_event_internal_t *)data;
  
  if (event->seen == TRUE || event->sent == TRUE)
    return;
  
  if (event->event->cookie != 0)
    {
      /* When we get a MOVED_FROM event we delay sending the event by
       * MOVE_HOLD_UNTIL_TIME microseconds. We need to do this because a
       * MOVED_TO pair _might_ be coming in the near future */
      if (event->event->mask & IN_MOVED_FROM)
	{
	  g_hash_table_insert (cookie_hash, GINT_TO_POINTER (event->event->cookie), event);
	  /* because we don't deliver move events there is no point in waiting for the match right now. */
	  ik_event_add_microseconds (event, MOVE_HOLD_UNTIL_TIME);
	}
      else if (event->event->mask & IN_MOVED_TO)
	{
	  /* We need to check if we are waiting for this MOVED_TO events cookie to pair it with
	   * a MOVED_FROM */
	  ik_event_internal_t *match = NULL;
	  match = g_hash_table_lookup (cookie_hash, GINT_TO_POINTER (event->event->cookie));
	  if (match)
	    {
	      g_hash_table_remove (cookie_hash, GINT_TO_POINTER (event->event->cookie));
	      ik_pair_events (match, event);
	    }
	}
    }
  event->seen = TRUE;
}

static void
ik_process_events (void)
{
  g_queue_foreach (events_to_process, ik_pair_moves, NULL);

  while (!g_queue_is_empty (events_to_process))
    {
      ik_event_internal_t *event = g_queue_peek_head (events_to_process);
      
      /* This must have been sent as part of a MOVED_TO/MOVED_FROM */
      if (event->sent)
	{
	  /* Pop event */
	  g_queue_pop_head (events_to_process);
	  /* Free the internal event structure */
	  g_free (event);
	  continue;
	}
      
      /* The event isn't ready yet */
      if (!ik_event_ready (event))
	break;
      
      /* Pop it */
      event = g_queue_pop_head (events_to_process);
      
      /* Check if this is a MOVED_FROM that is also sitting in the cookie_hash */
      if (event->event->cookie && event->pair == NULL &&
	  g_hash_table_lookup (cookie_hash, GINT_TO_POINTER (event->event->cookie)))
	g_hash_table_remove (cookie_hash, GINT_TO_POINTER (event->event->cookie));
      
      if (event->pair)
	{
	  /* We send out paired MOVED_FROM/MOVED_TO events in the same event buffer */
	  /* g_assert (event->event->mask == IN_MOVED_FROM && event->pair->event->mask == IN_MOVED_TO); */
	  /* Copy the paired data */
	  event->pair->sent = TRUE;
	  event->sent = TRUE;
	  ik_move_matches++;
	}
      else if (event->event->cookie)
	{
	  /* If we couldn't pair a MOVED_FROM and MOVED_TO together, we change
	   * the event masks */
	  /* Changeing MOVED_FROM to DELETE and MOVED_TO to create lets us make
	   * the gaurantee that you will never see a non-matched MOVE event */
	  
	  if (event->event->mask & IN_MOVED_FROM)
	    {
	      event->event->mask = IN_DELETE|(event->event->mask & IN_ISDIR);
	      ik_move_misses++; /* not super accurate, if we aren't watching the destination it still counts as a miss */
	    }
	  if (event->event->mask & IN_MOVED_TO)
	    event->event->mask = IN_CREATE|(event->event->mask & IN_ISDIR);
	}
      
      /* Push the ik_event_t onto the event queue */
      g_queue_push_tail (event_queue, event->event);
      /* Free the internal event structure */
      g_free (event);
    }
}

static gboolean
ik_process_eq_callback (gpointer user_data)
{
  gboolean res;
  
  /* Try and move as many events to the event queue */
  G_LOCK (inotify_lock);
  ik_process_events ();
  
  while (!g_queue_is_empty (event_queue))
    {
      ik_event_t *event = g_queue_pop_head (event_queue);
      
      user_cb (event);
    }

  res = TRUE;
  
  if (g_queue_get_length (events_to_process) == 0)
    {
      process_eq_running = FALSE;
      res = FALSE;
    }
  
  G_UNLOCK (inotify_lock);
  
  return res;
}