Rather than potentially making multiple passes over the same type of
data in the database, reorganize upgrade around each type of data that
may be upgraded.  This eliminates code duplication, will make
multi-version upgrades faster, and will let us improve progress
reporting.
---
 lib/database.cc | 71 +++++++++++++++++++++------------------------------------
 1 file changed, 26 insertions(+), 45 deletions(-)

diff --git a/lib/database.cc b/lib/database.cc
index 1dd2cd9..155cbac 100644
--- a/lib/database.cc
+++ b/lib/database.cc
@@ -1243,11 +1243,9 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
     /* Perform the upgrade in a transaction. */
     db->begin_transaction (true);
 
-    /* Before version 1, each message document had its filename in the
-     * data field. Copy that into the new format by calling
-     * notmuch_message_add_filename.
-     */
-    if (new_features & NOTMUCH_FEATURE_FILE_TERMS) {
+    /* Perform per-message upgrades. */
+    if (new_features &
+	(NOTMUCH_FEATURE_FILE_TERMS | NOTMUCH_FEATURE_BOOL_FOLDER)) {
 	notmuch_query_t *query = notmuch_query_create (notmuch, "");
 	notmuch_messages_t *messages;
 	notmuch_message_t *message;
@@ -1266,13 +1264,28 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
 
 	    message = notmuch_messages_get (messages);
 
-	    filename = _notmuch_message_talloc_copy_data (message);
-	    if (filename && *filename != '\0') {
-		_notmuch_message_add_filename (message, filename);
-		_notmuch_message_clear_data (message);
+	    /* Before version 1, each message document had its
+	     * filename in the data field. Copy that into the new
+	     * format by calling notmuch_message_add_filename.
+	     */
+	    if (new_features & NOTMUCH_FEATURE_FILE_TERMS) {
+		filename = _notmuch_message_talloc_copy_data (message);
+		if (filename && *filename != '\0') {
+		    _notmuch_message_add_filename (message, filename);
+		    _notmuch_message_clear_data (message);
+		    _notmuch_message_sync (message);
+		}
+		talloc_free (filename);
+	    }
+
+	    /* Prior to version 2, the "folder:" prefix was
+	     * probabilistic and stemmed. Change it to the current
+	     * boolean prefix. Add "path:" prefixes while at it.
+	     */
+	    if (new_features & NOTMUCH_FEATURE_BOOL_FOLDER) {
+		_notmuch_message_upgrade_folder (message);
 		_notmuch_message_sync (message);
 	    }
-	    talloc_free (filename);
 
 	    notmuch_message_destroy (message);
 
@@ -1282,7 +1295,9 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
 	notmuch_query_destroy (query);
     }
 
-    /* Also, before version 1 we stored directory timestamps in
+    /* Perform per-directory upgrades. */
+
+    /* Before version 1 we stored directory timestamps in
      * XTIMESTAMP documents instead of the current XDIRECTORY
      * documents. So copy those as well. */
     if (new_features & NOTMUCH_FEATURE_DIRECTORY_DOCS) {
@@ -1324,40 +1339,6 @@ notmuch_database_upgrade (notmuch_database_t *notmuch,
 	}
     }
 
-    /*
-     * Prior to version 2, the "folder:" prefix was probabilistic and
-     * stemmed. Change it to the current boolean prefix. Add "path:"
-     * prefixes while at it.
-     */
-    if (new_features & NOTMUCH_FEATURE_BOOL_FOLDER) {
-	notmuch_query_t *query = notmuch_query_create (notmuch, "");
-	notmuch_messages_t *messages;
-	notmuch_message_t *message;
-
-	count = 0;
-	total = notmuch_query_count_messages (query);
-
-	for (messages = notmuch_query_search_messages (query);
-	     notmuch_messages_valid (messages);
-	     notmuch_messages_move_to_next (messages)) {
-	    if (do_progress_notify) {
-		progress_notify (closure, (double) count / total);
-		do_progress_notify = 0;
-	    }
-
-	    message = notmuch_messages_get (messages);
-
-	    _notmuch_message_upgrade_folder (message);
-	    _notmuch_message_sync (message);
-
-	    notmuch_message_destroy (message);
-
-	    count++;
-	}
-
-	notmuch_query_destroy (query);
-    }
-
     notmuch->features = target_features;
     db->set_metadata ("features", _print_features (local, notmuch->features));
     db->set_metadata ("version", STRINGIFY (NOTMUCH_DATABASE_VERSION));
-- 
2.0.0