lib-storage: string sort - Write sort extensions in message sequence order

This optimizes CPU usage by changing inserting into the middle of an array
into an append-only operation.

diff --git a/src/lib-storage/index/index-sort-string.c b/src/lib-storage/index/index-sort-string.c
index 5d23bf0d5bc75549c42ec849e3bd9f8d6edd370a..b873ea3d831a27fcee6fcc06cce8f17ccffa7338 100644 (file)
--- a/src/lib-storage/index/index-sort-string.c
+++ b/src/lib-storage/index/index-sort-string.c
@@ -773,6 +773,8 @@ static void index_sort_write_changed_sort_ids(struct sort_string_context *ctx)
                        lowest_failed_seq = seq;
        }
 
+       ARRAY_TYPE(mail_sort_node) sorted_by_seq;
+       i_array_init(&sorted_by_seq, array_count(&ctx->sorted_nodes));
        /* add the missing sort IDs to index, but only for those sequences
           that are below lowest_failed_seq */
        nodes = array_get(&ctx->sorted_nodes, &count);
@@ -782,9 +784,17 @@ static void index_sort_write_changed_sort_ids(struct sort_string_context *ctx)
                    nodes[i].seq >= lowest_failed_seq)
                        continue;
 
+               array_push_back(&sorted_by_seq, &nodes[i]);
+       }
+       /* update extensions in sequence order so the records are always
+          appended. */
+       array_sort(&sorted_by_seq, sort_node_seq_cmp);
+       nodes = array_get(&sorted_by_seq, &count);
+       for (i = 0; i < count; i++) {
                mail_index_update_ext(itrans, nodes[i].seq, ext_id,
                                      &nodes[i].sort_id, NULL);
        }
+       array_free(&sorted_by_seq);
 }
 
 static int sort_node_cmp(const struct mail_sort_node *n1,