[PATCH 1/3] new: Do not defer maildir flag synchronization during the first run

[Michal Sojka <sojkam1@fel.cvut.cz>]

When notmuch new is run for the first time, it is not necessary to defer
maildir flags synchronization to later because we already know that no
files will be removed.

Performing the maildinr flag synchronization immediately after the
message is added to the database has the advantage that the message is
likely hot in the disk cache so the synchronization is faster.
Additionally, we also save one database query for each message, which
must be performed when the operation is deferred.

Without this patchi, the first notmuch new of 200k messages (3 GB) took
1h and 46m out of which 20m was maildir flags synchronization. With this
patch, the whole operation took only 1h and 36m.
---
 notmuch-new.c |   36 ++++++++++++++++++++++++++----------
 1 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/notmuch-new.c b/notmuch-new.c
index cdf8513..a2af045 100644
--- a/notmuch-new.c
+++ b/notmuch-new.c
@@ -420,19 +420,35 @@ add_files_recursive (notmuch_database_t *notmuch,
 	    state->added_messages++;
 	    for (tag=state->new_tags; *tag != NULL; tag++)
 	        notmuch_message_add_tag (message, *tag);
-	    /* Defer sync of maildir flags until after old filenames
-	     * are removed in the case of a rename. */
-	    if (state->synchronize_flags == TRUE)
-		_filename_list_add (state->message_ids_to_sync,
-				    notmuch_message_get_message_id (message));
+	    if (state->synchronize_flags == TRUE) {
+		if (!state->total_files) {
+		    /* Defer sync of maildir flags until after old filenames
+		     * are removed in the case of a rename. */
+		    _filename_list_add (state->message_ids_to_sync,
+					notmuch_message_get_message_id (message));
+		} else {
+		    /* During the first notmuch new we synchronize
+		     * flags immediately, while the message is hot in
+		     * disk cache. */
+		    notmuch_message_maildir_flags_to_tags (message);
+		}
+	    }
 	    break;
 	/* Non-fatal issues (go on to next file) */
 	case NOTMUCH_STATUS_DUPLICATE_MESSAGE_ID:
-	    /* Defer sync of maildir flags until after old filenames
-	     * are removed in the case of a rename. */
-	    if (state->synchronize_flags == TRUE)
-		_filename_list_add (state->message_ids_to_sync,
-				    notmuch_message_get_message_id (message));
+	    if (state->synchronize_flags == TRUE) {
+		if (!state->total_files) {
+		    /* Defer sync of maildir flags until after old filenames
+		     * are removed in the case of a rename. */
+		    _filename_list_add (state->message_ids_to_sync,
+					notmuch_message_get_message_id (message));
+		} else {
+		    /* During the first notmuch new we synchronize
+		     * flags immediately, while the message is hot in
+		     * disk cache. */
+		    notmuch_message_maildir_flags_to_tags (message);
+		}
+	    }
 	    break;
 	case NOTMUCH_STATUS_FILE_NOT_EMAIL:
 	    fprintf (stderr, "Note: Ignoring non-mail file: %s\n",
-- 
1.7.2.3