[Patch v3b 9/9] tag-util: optimization of tag application
david at tethera.net
david at tethera.net
Thu Dec 6 17:26:47 PST 2012
From: David Bremner <bremner at debian.org>
The idea is not to bother with restore operations if they don't change
the set of tags. This is actually a relatively common case.
In order to avoid fancy datastructures, this method is quadratic in
the number of tags; at least on my mail database this doesn't seem to
be a big problem.
---
tag-util.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 66 insertions(+)
diff --git a/tag-util.c b/tag-util.c
index 932ee7f..3d54e9e 100644
--- a/tag-util.c
+++ b/tag-util.c
@@ -124,6 +124,69 @@ message_error (notmuch_message_t *message,
fprintf (stderr, "Status: %s\n", notmuch_status_to_string (status));
}
+static int
+makes_changes (notmuch_message_t *message,
+ tag_op_list_t *list,
+ tag_op_flag_t flags)
+{
+
+ size_t i;
+
+ notmuch_tags_t *tags;
+ notmuch_bool_t changes = FALSE;
+
+ /* First, do we delete an existing tag? */
+ changes = FALSE;
+ for (tags = notmuch_message_get_tags (message);
+ ! changes && notmuch_tags_valid (tags);
+ notmuch_tags_move_to_next (tags)) {
+ const char *cur_tag = notmuch_tags_get (tags);
+ int last_op = (flags & TAG_FLAG_REMOVE_ALL) ? -1 : 0;
+
+ /* slight contortions to count down with an unsigned index */
+ for (i = list->count; i-- > 0; /*nothing*/) {
+ if (strcmp (cur_tag, list->ops[i].tag) == 0) {
+ last_op = list->ops[i].remove ? -1 : 1;
+ break;
+ }
+ }
+
+ changes = (last_op == -1);
+ }
+ notmuch_tags_destroy (tags);
+
+ if (changes)
+ return TRUE;
+
+ /* Now check for adding new tags */
+ for (i = 0; i < list->count; i++) {
+ notmuch_bool_t exists = FALSE;
+
+ if (list->ops[i].remove)
+ continue;
+
+ for (tags = notmuch_message_get_tags (message);
+ notmuch_tags_valid (tags);
+ notmuch_tags_move_to_next (tags)) {
+ const char *cur_tag = notmuch_tags_get (tags);
+ if (strcmp (cur_tag, list->ops[i].tag) == 0) {
+ exists = TRUE;
+ break;
+ }
+ }
+ notmuch_tags_destroy (tags);
+
+ /* the following test is conservative,
+ * in the sense it ignores cases like +foo ... -foo
+ * but this is OK from a correctness point of view
+ */
+ if (! exists)
+ return TRUE;
+ }
+ return FALSE;
+
+}
+
notmuch_status_t
tag_op_list_apply (notmuch_message_t *message,
tag_op_list_t *list,
@@ -133,6 +196,9 @@ tag_op_list_apply (notmuch_message_t *message,
notmuch_status_t status = 0;
tag_operation_t *tag_ops = list->ops;
+ if (! (flags & TAG_FLAG_PRE_OPTIMIZED) && ! makes_changes (message, list, flags))
+ return NOTMUCH_STATUS_SUCCESS;
+
status = notmuch_message_freeze (message);
if (status) {
message_error (message, status, "freezing message");
--
1.7.10.4
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