[tracker/duplicates-after-interrupts] libtracker-miner: loop until a successful query in item_query_exists()

[Aleksander Morgado <aleksm src gnome org>]

commit 5f8b55ae9854e677b5169e806dcb8e1eb7dd890c
Author: Aleksander Morgado <aleksander lanedo com>
Date:   Tue Jul 13 13:10:15 2010 +0200

    libtracker-miner: loop until a successful query in item_query_exists()

 src/libtracker-miner/tracker-miner-fs.c |   48 ++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 13 deletions(-)
---
diff --git a/src/libtracker-miner/tracker-miner-fs.c b/src/libtracker-miner/tracker-miner-fs.c
index 1903257..fddb6a5 100644
--- a/src/libtracker-miner/tracker-miner-fs.c
+++ b/src/libtracker-miner/tracker-miner-fs.c
@@ -72,6 +72,7 @@ typedef struct {
 	gchar *iri;
 	gchar *mime;
 	gboolean get_mime;
+	GError *error;
 } ItemQueryExistsData;
 
 typedef struct {
@@ -1073,17 +1074,15 @@ item_query_exists_cb (GObject      *object,
 	ItemQueryExistsData *data = user_data;
 	TrackerResultIterator *iterator;
 	TrackerMiner *miner;
-	GError *error = NULL;
 	guint n_results;
 
 	miner = TRACKER_MINER (object);
-	iterator = tracker_miner_execute_sparql_finish (miner, result, &error);
+	iterator = tracker_miner_execute_sparql_finish (miner, result, &data->error);
 
 	g_main_loop_quit (data->main_loop);
 
-	if (error) {
-		g_critical ("Could not execute sparql query: %s", error->message);
-		g_error_free (error);
+	/* If any error found during query, like an Interrupt, return */
+	if (data->error) {
 		return;
 	}
 
@@ -1120,9 +1119,11 @@ item_query_exists (TrackerMinerFS  *miner,
                    gchar          **iri,
                    gchar          **mime)
 {
-	gboolean   result;
-	gchar     *sparql, *uri;
+	gboolean result;
+	gchar *sparql;
+	gchar *uri;
 	ItemQueryExistsData data = { 0 };
+	guint n_retries = 0;
 
 	data.get_mime = (mime != NULL);
 
@@ -1137,13 +1138,34 @@ item_query_exists (TrackerMinerFS  *miner,
 	data.main_loop = g_main_loop_new (NULL, FALSE);
 	data.uri = uri;
 
-	tracker_miner_execute_sparql (TRACKER_MINER (miner),
-	                              sparql,
-	                              NULL,
-	                              item_query_exists_cb,
-	                              &data);
+	/* Loop to make sure that we ALWAYS get a successful reply
+	 * here. If we get interrupted, for example, we need to retry.
+	 * This loop will run forever until we get a proper result,
+	 * otherwise we'll end up with duplicates in the store */
+	while (1) {
+		tracker_miner_execute_sparql (TRACKER_MINER (miner),
+		                              sparql,
+		                              NULL,
+		                              item_query_exists_cb,
+		                              &data);
+
+		g_main_loop_run (data.main_loop);
+
+		if (data.error) {
+			/* Note that data.iri and data.mime cannot be
+			 * initialized in this case */
+			g_message ("RETRYING (%u) after failed query for existence of item '%s': '%s'",
+			           ++n_retries,
+			           uri,
+			           data.error->message);
+			g_error_free (data.error);
+			data.error = NULL;
+		} else {
+			/* Successful reply from store, we can safely go on */
+			break;
+		}
+	}
 
-	g_main_loop_run (data.main_loop);
 	result = (data.iri != NULL);
 
 	g_main_loop_unref (data.main_loop);