Added mutex to protect map pixbuf cache from being corrupted.

Since the ring list and the hash and other house keeping data for the
pixbuf cache are modified by (map download) threads, there are potentional
problems of data corruption. A mutex was added to address the problem.

Signed-off-by: Quy Tonthat <qtonthat@gmail.com>

diff --git a/ChangeLog b/ChangeLog
index ac0bc76d3d2a6f5f150ad74a6e81aabd177bd914..9b14096b6aff57d96c691afed25f2c6b969a9413 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-1-18
+Qut Tonthat <qtonthat@gmail.com>:
+       * Fix a crash bug in mapcache reported by Jocelyn <jocelyn.jaubert@gmail.com>
+       * Added mutex to protect mapcache from being corrupted by threads.
+
 2008-01-04:
 Alex Foobarian <foobarian@gmail.com>:
        * Tuned the v-t diagram drawing

diff --git a/src/mapcache.c b/src/mapcache.c
index 3dd8023a118d7146d9f89cee08a00d44f7584aa5..ffaa3528bcfbfd6fe632f3b20def8f04b5877fd2 100644 (file)
--- a/src/mapcache.c
+++ b/src/mapcache.c
@@ -40,11 +40,14 @@ static guint32 queue_size = 0;
 
 static GHashTable *cache = NULL;
 
+static GMutex *mc_mutex = NULL;
+
 #define HASHKEY_FORMAT_STRING "%d-%d-%d-%d-%d-%d-%.3f-%.3f"
 #define HASHKEY_FORMAT_STRING_NOSHRINK_NOR_ALPHA "%d-%d-%d-%d-%d-"
 
 void a_mapcache_init ()
 {
+  mc_mutex = g_mutex_new();
   cache = g_hash_table_new_full ( g_str_hash, g_str_equal, g_free, g_object_unref );
 }
 
@@ -106,6 +109,7 @@ void a_mapcache_add ( GdkPixbuf *pixbuf, gint x, gint y, gint z, guint8 type, gu
   gchar *key = g_strdup_printf ( HASHKEY_FORMAT_STRING, x, y, z, type, zoom, alpha, xshrinkfactor, yshrinkfactor );
   static int tmp = 0;
 
+  g_mutex_lock(mc_mutex);
   cache_add(key, pixbuf);
 
   if ( queue_size > VIK_CONFIG_MAPCACHE_SIZE ) {
@@ -123,6 +127,7 @@ void a_mapcache_add ( GdkPixbuf *pixbuf, gint x, gint y, gint z, guint8 type, gu
     list_add_entry ( key );
     /* business as usual */
   }
+  g_mutex_unlock(mc_mutex);
 
   if ( (++tmp == 100 ))  { g_print("DEBUG: queue count=%d %u\n", queue_count, queue_size ); tmp=0; }
 }
@@ -147,6 +152,7 @@ void a_mapcache_remove_all_shrinkfactors ( gint x, gint y, gint z, guint8 type,
   g_snprintf ( key, sizeof(key), HASHKEY_FORMAT_STRING_NOSHRINK_NOR_ALPHA, x, y, z, type, zoom );
   len = strlen(key);
 
+  g_mutex_lock(mc_mutex);
   /* TODO: check logic here */
   do {
     tmp = loop->next;
@@ -170,6 +176,7 @@ void a_mapcache_remove_all_shrinkfactors ( gint x, gint y, gint z, guint8 type,
 
   /* loop thru list, looking for the one, compare first whatever chars */
   cache_remove(key);
+  g_mutex_unlock(mc_mutex);
 }
 
 void a_mapcache_uninit ()