Sort index optimization: Don't write changes to sort IDs if we're doing it

only to give sort ID space to expunged messages.

--HG--
branch : HEAD

diff --git a/src/lib-storage/index/index-sort-string.c b/src/lib-storage/index/index-sort-string.c
index bad706ce012c76204dd10b15b0dd518291140245..f420229713fbfa4464ce800517ee1e3afb6c0941 100644 (file)
--- a/src/lib-storage/index/index-sort-string.c
+++ b/src/lib-storage/index/index-sort-string.c
@@ -34,6 +34,7 @@ struct sort_string_context {
        unsigned int first_missing_sort_id_idx;
 
        uint32_t ext_id, last_seq, highest_reset_id;
+       uint32_t lowest_nonexpunged_zero;
 
        unsigned int regetting:1;
        unsigned int have_all_wanted:1;
@@ -157,6 +158,14 @@ static void index_sort_node_add(struct sort_string_context *ctx,
                node->sort_id = 0;
        } else {
                node->sort_id = data == NULL ? 0 : *(const uint32_t *)data;
+               if (node->sort_id == 0) {
+                       if (ctx->lowest_nonexpunged_zero > node->seq ||
+                           ctx->lowest_nonexpunged_zero == 0)
+                               ctx->lowest_nonexpunged_zero = node->seq;
+               } else {
+                       i_assert(ctx->lowest_nonexpunged_zero == 0 ||
+                                ctx->lowest_nonexpunged_zero > node->seq);
+               }
        }
 
        if (node->sort_id != 0) {
@@ -669,6 +678,12 @@ static void index_sort_add_missing(struct sort_string_context *ctx)
                        next_seq = seqs[i] + 1;
                }
        }
+
+       if (ctx->lowest_nonexpunged_zero == 0) {
+               /* we're handling only expunged zeros. if it causes us to
+                  renumber some existing sort IDs, don't save them. */
+               ctx->no_writing = TRUE;
+       }
 }
 
 void index_sort_list_finish_string(struct mail_search_sort_program *program)