[tracker] libtracker-data: After journal replay modseq must get restored

[Jürg Billeter <juergbi src gnome org>]

commit b1c7260081166884f9ef1b68f7db38cb8fba3eaa
Author: Philip Van Hoof <philip codeminded be>
Date:   Thu Jan 27 13:31:48 2011 +0100

    libtracker-data: After journal replay modseq must get restored
    
    This commit changes how the modification-sequence works, this is
    made public using the tracker:modified property on resource.
    
    Instead of each resource having its own unique modification-
    sequence number, the modification sequences are defined per
    committed transaction that had properties that aren't transient.
    
    This commit also changes the fact that a transaction with only
    transient properties was still adding an empty transaction to
    the journal. With that the modification sequence wouldn't
    restore correctly to original state. It wasn't needed, so this
    change removes the empty transaction in the journal in that
    special case.

 src/libtracker-data/tracker-data-manager.c |    4 +-
 src/libtracker-data/tracker-data-update.c  |   60 ++++++++++++++++++++-------
 2 files changed, 46 insertions(+), 18 deletions(-)
---
diff --git a/src/libtracker-data/tracker-data-manager.c b/src/libtracker-data/tracker-data-manager.c
index 441f396..86e8c08 100644
--- a/src/libtracker-data/tracker-data-manager.c
+++ b/src/libtracker-data/tracker-data-manager.c
@@ -3224,10 +3224,10 @@ tracker_data_manager_init (TrackerDBManagerFlags  flags,
 	GHashTable *uri_id_map = NULL;
 	gchar *busy_status;
 
-	tracker_data_update_init ();
-
 	read_only = (flags & TRACKER_DB_MANAGER_READONLY) ? TRUE : FALSE;
 
+	tracker_data_update_init ();
+
 	/* First set defaults for return values */
 	if (first_time) {
 		*first_time = FALSE;
diff --git a/src/libtracker-data/tracker-data-update.c b/src/libtracker-data/tracker-data-update.c
index 2982848..ffabaa8 100644
--- a/src/libtracker-data/tracker-data-update.c
+++ b/src/libtracker-data/tracker-data-update.c
@@ -151,6 +151,8 @@ static TrackerDataUpdateBuffer update_buffer;
 static TrackerDataUpdateBufferResource *resource_buffer;
 static TrackerDataBlankBuffer blank_buffer;
 static time_t resource_time = 0;
+static gint transaction_modseq = 0;
+static gboolean has_persistent = TRUE;
 
 static GPtrArray *insert_callbacks = NULL;
 static GPtrArray *delete_callbacks = NULL;
@@ -158,7 +160,6 @@ static GPtrArray *commit_callbacks = NULL;
 static GPtrArray *rollback_callbacks = NULL;
 static gint max_service_id = 0;
 static gint max_ontology_id = 0;
-static gint max_modseq = 0;
 
 static gint         ensure_resource_id      (const gchar      *uri,
                                              gboolean         *create);
@@ -413,14 +414,6 @@ tracker_data_update_get_new_service_id (void)
 	}
 }
 
-void
-tracker_data_update_shutdown (void)
-{
-	max_service_id = 0;
-	max_ontology_id = 0;
-	max_modseq = 0;
-}
-
 static gint
 tracker_data_update_get_next_modseq (void)
 {
@@ -428,10 +421,7 @@ tracker_data_update_get_next_modseq (void)
 	TrackerDBInterface *temp_iface;
 	TrackerDBStatement *stmt;
 	GError             *error = NULL;
-
-	if (G_LIKELY (max_modseq != 0)) {
-		return ++max_modseq;
-	}
+	gint                max_modseq = 0;
 
 	temp_iface = tracker_db_manager_get_db_interface ();
 
@@ -459,6 +449,23 @@ tracker_data_update_get_next_modseq (void)
 	return ++max_modseq;
 }
 
+void
+tracker_data_update_shutdown (void)
+{
+	max_service_id = 0;
+	max_ontology_id = 0;
+	transaction_modseq = 0;
+}
+
+static gint
+get_transaction_modseq (void)
+{
+	if (G_UNLIKELY (transaction_modseq == 0)) {
+		transaction_modseq = tracker_data_update_get_next_modseq ();
+	}
+
+	return transaction_modseq;
+}
 
 static TrackerDataUpdateBufferTable *
 cache_table_new (gboolean multiple_values)
@@ -502,7 +509,7 @@ cache_ensure_table (const gchar *table_name,
 		resource_buffer->modified = TRUE;
 
 		g_value_init (&gvalue, G_TYPE_INT64);
-		g_value_set_int64 (&gvalue, tracker_data_update_get_next_modseq ());
+		g_value_set_int64 (&gvalue, get_transaction_modseq ());
 		cache_insert_value ("rdfs:Resource", "tracker:modified", TRUE, &gvalue,
 		                    0,
 		                    FALSE, FALSE, FALSE);
@@ -552,6 +559,10 @@ cache_insert_value (const gchar            *table_name,
 #endif
 	property.date_time = date_time;
 
+	if (!transient) {
+		has_persistent = TRUE;
+	}
+
 	table = cache_ensure_table (table_name, multiple_values, transient);
 	g_array_append_val (table->properties, property);
 }
@@ -586,6 +597,10 @@ cache_delete_value (const gchar            *table_name,
 #endif
 	property.date_time = date_time;
 
+	if (!transient) {
+		has_persistent = TRUE;
+	}
+
 	table = cache_ensure_table (table_name, multiple_values, transient);
 	table->delete_value = TRUE;
 	g_array_append_val (table->properties, property);
@@ -887,7 +902,7 @@ tracker_data_resource_buffer_flush (GError **error)
 				if (strcmp (table_name, "rdfs:Resource") == 0) {
 					g_warn_if_fail	(resource_time != 0);
 					tracker_db_statement_bind_int (stmt, 1, (gint64) resource_time);
-					tracker_db_statement_bind_int (stmt, 2, tracker_data_update_get_next_modseq ());
+					tracker_db_statement_bind_int (stmt, 2, get_transaction_modseq ());
 					param = 3;
 				} else {
 					param = 1;
@@ -2395,6 +2410,8 @@ tracker_data_begin_transaction (GError **error)
 
 	resource_time = time (NULL);
 
+	has_persistent = FALSE;
+
 	if (update_buffer.resource_cache == NULL) {
 		update_buffer.resource_cache = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
 		/* used for normal transactions */
@@ -2459,10 +2476,21 @@ tracker_data_commit_transaction (GError **error)
 	}
 
 	in_transaction = FALSE;
+	get_transaction_modseq ();
+	if (has_persistent) {
+		transaction_modseq++;
+	}
 	in_ontology_transaction = FALSE;
 
 	if (!in_journal_replay) {
-		tracker_db_journal_commit_db_transaction ();
+		if (has_persistent) {
+			tracker_db_journal_commit_db_transaction ();
+		} else {
+			/* If we only had transient properties, then we must not write
+			 * anything to the journal. So we roll it back, but only the
+			 * journal's part. */
+			tracker_db_journal_rollback_transaction ();
+		}
 	}
 	resource_time = 0;