[tracker] libtracker-miner: Ensure proper task queues when crawling

[Aleksander Morgado <aleksm src gnome org>]

commit 22087297bd7fd9c571c4ccc95c09dacae1cc7608
Author: Aleksander Morgado <aleksander lanedo com>
Date:   Mon Dec 13 18:48:31 2010 +0100

    libtracker-miner: Ensure proper task queues when crawling
    
     If a directory is being crawled (as for example when renaming a directory
     from an ignored name to a non-ignored one), ensure that items found during
     crawling are processed only after any other task on the same paths has
     finished (as for example when we're deleting a whole directory and all its
     contents, which take a lot of time).
    
     To test this, prepare a directory with tons of files inside which is
     monitored by tracker (named 'not-hidden' for example), and then:
        1. $> mv not-hidden .hidden
        2. wait some seconds (previous action should still be processing in the store)
        3. $> mv .hidden not-hidden
        4. The addition of all items found during the crawling of 'not-hidden'
           should wait until the action in step 1 is finished in the store.
    
     Before this patch, for each directory found during crawling we were calling
     item_query_exists() and that was returning TRUE even if it was currently
     being processed to be removed. Also, before this patch, ensuring the mtime
     cache was done querying the store, which was returning items even if they
     were also currently being processed to be removed.

 src/libtracker-miner/tracker-miner-fs.c |   56 ++++++++++++++++++++++++++-----
 1 files changed, 47 insertions(+), 9 deletions(-)
---
diff --git a/src/libtracker-miner/tracker-miner-fs.c b/src/libtracker-miner/tracker-miner-fs.c
index 05fd94e..4db3178 100644
--- a/src/libtracker-miner/tracker-miner-fs.c
+++ b/src/libtracker-miner/tracker-miner-fs.c
@@ -117,6 +117,7 @@ struct _TrackerMinerFSPrivate {
 
 	GQuark          quark_ignore_file;
 	GQuark          quark_attribute_updated;
+	GQuark          quark_check_existence;
 
 	GList          *config_directories;
 
@@ -620,6 +621,7 @@ tracker_miner_fs_init (TrackerMinerFS *object)
 	                  object);
 
 	priv->quark_ignore_file = g_quark_from_static_string ("tracker-ignore-file");
+	priv->quark_check_existence = g_quark_from_static_string ("tracker-check-existence");
 	priv->quark_attribute_updated = g_quark_from_static_string ("tracker-attribute-updated");
 
 	priv->iri_cache = g_hash_table_new_full (g_file_hash,
@@ -2512,6 +2514,24 @@ item_queue_handlers_cb (gpointer user_data)
 		keep_processing = item_remove (fs, file);
 		break;
 	case QUEUE_CREATED:
+		/* Check existence before processing, if requested to do so. */
+		if (g_object_get_qdata (G_OBJECT (file),
+		                        fs->private->quark_check_existence)) {
+			/* Clear the qdata */
+			g_object_set_qdata (G_OBJECT (file),
+			                    fs->private->quark_check_existence,
+			                    GINT_TO_POINTER (FALSE));
+			/* Avoid adding items that already exist, when processing
+			 * a CREATED task (as those generated when crawling) */
+			if (!item_query_exists (fs, file, NULL, NULL)) {
+				keep_processing = item_add_or_update (fs, file);
+				break;
+			}
+			/* If already in store, skip processing the CREATED task */
+			keep_processing = TRUE;
+			break;
+		}
+		/* Else, fall down and treat as QUEUE_UPDATED */
 	case QUEUE_UPDATED:
 		keep_processing = item_add_or_update (fs, file);
 		break;
@@ -2682,6 +2702,21 @@ ensure_mtime_cache (TrackerMinerFS *fs,
 
 	g_hash_table_remove_all (fs->private->mtime_cache);
 
+	/* Hack hack alert!
+	 * Before querying the store, check if the parent directory is scheduled to
+	 * be added, and if so, leave the mtime cache empty.
+	 */
+	if (g_queue_find_custom (fs->private->items_created,
+	                         parent,
+	                         (GCompareFunc)tracker_file_cmp) != NULL) {
+		uri = g_file_get_uri (file);
+		g_debug ("Empty mtime cache for URI '%s' "
+		         "(parent scheduled to be created)",
+		         uri);
+		g_free (uri);
+		return;
+	}
+
 	if (!parent || (!is_parent && file_is_crawl_directory (fs, file))) {
 		/* File is a crawl directory itself, query its mtime directly */
 		uri = g_file_get_uri (file);
@@ -2877,6 +2912,7 @@ should_check_file (TrackerMinerFS *fs,
 	} else {
 		g_signal_emit (fs, signals[CHECK_FILE], 0, file, &should_check);
 	}
+
 	return should_check;
 }
 
@@ -2895,7 +2931,6 @@ should_process_file (TrackerMinerFS *fs,
 			g_queue_push_tail (fs->private->items_deleted,
 			                   g_object_ref (file));
 		}
-
 		return FALSE;
 	}
 
@@ -3254,14 +3289,17 @@ crawler_check_directory_contents_cb (TrackerCrawler *crawler,
 	 * the finished sig?
 	 */
 	if (add_monitor) {
-		if (!item_query_exists (fs, parent, NULL, NULL)) {
-			/* Before adding the monitor, start notifying the store
-			 * about the new directory, so that if any file event comes
-			 * afterwards, the directory is already in store. */
-			g_queue_push_tail (fs->private->items_created,
-			                   g_object_ref (parent));
-			item_queue_handlers_set_up (fs);
-		}
+		/* Set quark so that before trying to add the item we first
+		 * check for its existence. */
+		g_object_set_qdata (G_OBJECT (parent),
+		                    fs->private->quark_check_existence,
+		                    GINT_TO_POINTER (TRUE));
+		/* Before adding the monitor, start notifying the store
+		 * about the new directory, so that if any file event comes
+		 * afterwards, the directory is already in store. */
+		g_queue_push_tail (fs->private->items_created,
+		                   g_object_ref (parent));
+		item_queue_handlers_set_up (fs);
 
 		/* As we already added here, specify that it shouldn't be added
 		 * any more */