gio/kqueue/kqueue-missing.c

   1 /*******************************************************************************
   2   Copyright (c) 2011, 2012 Dmitry Matveev <me@dmitrymatveev.co.uk>
   3
   4   Permission is hereby granted, free of charge, to any person obtaining a copy
   5   of this software and associated documentation files (the "Software"), to deal
   6   in the Software without restriction, including without limitation the rights
   7   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8   copies of the Software, and to permit persons to whom the Software is
   9   furnished to do so, subject to the following conditions:
  10
  11   The above copyright notice and this permission notice shall be included in
  12   all copies or substantial portions of the Software.
  13
  14   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  20   THE SOFTWARE.
  21 *******************************************************************************/
  22
  23 #include <glib.h>
  24
  25 #include "kqueue-helper.h"
  26 #include "kqueue-sub.h"
  27 #include "kqueue-missing.h"
  28
  29
  30 #define SCAN_MISSING_TIME 4 /* 1/4 Hz */
  31
  32 static gboolean km_scan_missing (gpointer user_data);
  33
  34 static gboolean km_debug_enabled = FALSE;
  35 #define KM_W if (km_debug_enabled) g_warning
  36
  37 static GSList *missing_subs_list = NULL;
  38 G_LOCK_DEFINE_STATIC (missing_lock);
  39
  40 static volatile gboolean scan_missing_running = FALSE;
  41 static on_create_cb file_appeared_callback;
  42
  43
  44 /**
  45  * _km_init:
  46  * @cb: a callback function. It will be called when a watched file
  47  *     will appear.
  48  *
  49  * Initialize the kqueue-missing module (optional).
  50  **/
  51 void
  52 _km_init (on_create_cb cb)
  53 {
  54   file_appeared_callback = cb;
  55 }
  56
  57
  58 /**
  59  * _km_add_missing:
  60  * @sub: a #kqueue_sub
  61  *
  62  * Adds a subscription to the missing files list.
  63  **/
  64 void
  65 _km_add_missing (kqueue_sub *sub)
  66 {
  67   G_LOCK (missing_lock);
  68   if (g_slist_find (missing_subs_list, sub))
  69     {
  70       KM_W ("asked to add %s to missing list but it's already on the list!\n", sub->filename);
  71       return;
  72     }
  73
  74   KM_W ("adding %s to missing list\n", sub->filename);
  75   missing_subs_list = g_slist_prepend (missing_subs_list, sub);
  76   G_UNLOCK (missing_lock);
  77
  78   if (!scan_missing_running)
  79     {
  80       scan_missing_running = TRUE;
  81       g_timeout_add_seconds (SCAN_MISSING_TIME, km_scan_missing, NULL);
  82     }
  83 }
  84
  85
  86 /**
  87  * km_scan_missing:
  88  * @user_data: unused
  89  *
  90  * The core missing files watching routine.
  91  *
  92  * Traverses through a list of missing files, tries to start watching each with
  93  * kqueue, removes the appropriate entry and invokes a user callback if the file
  94  * has appeared.
  95  *
  96  * Returns: %FALSE if no missing files left, %TRUE otherwise.
  97  **/
  98 static gboolean
  99 km_scan_missing (gpointer user_data)
 100 {
 101   GSList *head;
 102   GSList *not_missing = NULL;
 103   gboolean retval = FALSE;
 104
 105   G_LOCK (missing_lock);
 106
 107   if (missing_subs_list)
 108     KM_W ("we have a job");
 109
 110   for (head = missing_subs_list; head; head = head->next)
 111     {
 112       kqueue_sub *sub = (kqueue_sub *) head->data;
 113       g_assert (sub != NULL);
 114       g_assert (sub->filename != NULL);
 115
 116       if (_kh_start_watching (sub))
 117         {
 118           KM_W ("file %s now exists, starting watching", sub->filename);
 119           if (file_appeared_callback)
 120             file_appeared_callback (sub);
 121           not_missing = g_slist_prepend (not_missing, head);
 122         }
 123     }
 124
 125   for (head = not_missing; head; head = head->next)
 126     {
 127       GSList *link = (GSList *) head->data;
 128       missing_subs_list = g_slist_remove_link (missing_subs_list, link);
 129     }
 130   g_slist_free (not_missing);
 131
 132   if (missing_subs_list == NULL)
 133     {
 134       scan_missing_running = FALSE;
 135       retval = FALSE;
 136     }
 137   else
 138     retval = TRUE;
 139
 140   G_UNLOCK (missing_lock);
 141   return retval;
 142 }
 143
 144
 145 /**
 146  * _km_remove:
 147  * @sub: a #kqueue_sub
 148  *
 149  * Removes a subscription from a list of missing files.
 150  **/
 151 void
 152 _km_remove (kqueue_sub *sub)
 153 {
 154   G_LOCK (missing_lock);
 155   missing_subs_list = g_slist_remove (missing_subs_list, sub);
 156   G_UNLOCK (missing_lock);
 157 }