Stop searching routerlist for routers with the same identity as other routers (on router insert): we already have a map for that. (We need to add an index field to routerinfo_t so we can figure out which point in the routerlist to replace.) Also, add a comment to routerlist.c; arma, please advise?

svn:r8432

ChangeLog

@@ -1,8 +1,9 @@
 Changes in version 0.1.2.2-alpha - 2006-??-??
 
   o Minor Bugfixes
-    - Small performance improvements on parsing and inserting
-      descriptors.
+    - Small performance improvements on parsing descriptors.
+    - Major performance descriptor on inserting descriptors; change
+      algorithm from O(n^2) to O(n). [Mostly.]
     - Make the common memory allocation path faster on machines where
       malloc(0) returns a pointer.
 

src/or/or.h

@@ -928,6 +928,10 @@ typedef struct {
   /** How many times has a descriptor been posted and we believed
    * this router to be unreachable? We only actually warn on the third. */
   int num_unreachable_notifications;
+
+  /** What position is this descriptor within routerlist->routers? -1 for
+   * none. */
+  int routerlist_index;
 } routerinfo_t;
 
 /** Contents of a single router entry in a network status object.

src/or/router.c

@@ -805,6 +805,7 @@ router_rebuild_descriptor(int force)
   }
 
   ri = tor_malloc_zero(sizeof(routerinfo_t));
+  ri->routerlist_index = -1;
   ri->address = tor_dup_addr(addr);
   ri->nickname = tor_strdup(options->Nickname);
   ri->addr = addr;

src/or/routerlist.c

@@ -1343,6 +1343,7 @@ routerlist_insert(routerlist_t *rl, routerinfo_t *ri)
   digestmap_set(rl->desc_digest_map, ri->cache_info.signed_descriptor_digest,
                 &(ri->cache_info));
   smartlist_add(rl->routers, ri);
+  ri->routerlist_index = smartlist_len(rl->routers) - 1;
   router_dir_info_changed();
   // routerlist_assert_ok(rl);
 }
@@ -1356,6 +1357,7 @@ routerlist_insert_old(routerlist_t *rl, routerinfo_t *ri)
     signed_descriptor_t *sd = signed_descriptor_from_routerinfo(ri);
     digestmap_set(rl->desc_digest_map, sd->signed_descriptor_digest, sd);
     smartlist_add(rl->old_routers, sd);
+    ri->routerlist_index = -1;
   } else {
     routerinfo_free(ri);
   }
@@ -1374,7 +1376,13 @@ routerlist_remove(routerlist_t *rl, routerinfo_t *ri, int idx, int make_old)
   idx = _routerlist_find_elt(rl->routers, ri, idx);
   if (idx < 0)
     return;
+  ri->routerlist_index = -1;
   smartlist_del(rl->routers, idx);
+  if (idx < smartlist_len(rl->routers)) {
+    routerinfo_t *r = smartlist_get(rl->routers, idx);
+    r->routerlist_index = idx;
+  }
+
   ri_tmp = digestmap_remove(rl->identity_map, ri->cache_info.identity_digest);
   router_dir_info_changed();
   tor_assert(ri_tmp == ri);
@@ -1423,6 +1431,8 @@ routerlist_replace(routerlist_t *rl, routerinfo_t *ri_old,
   router_dir_info_changed();
   if (idx >= 0) {
     smartlist_set(rl->routers, idx, ri_new);
+    ri_old->routerlist_index = -1;
+    ri_new->routerlist_index = idx;
   } else {
     log_warn(LD_BUG, "Appending entry from routerlist_replace.");
     routerlist_insert(rl, ri_new);
@@ -1606,10 +1616,10 @@ int
 router_add_to_routerlist(routerinfo_t *router, const char **msg,
                          int from_cache, int from_fetch)
 {
-  int i;
   const char *id_digest;
   int authdir = get_options()->AuthoritativeDir;
   int authdir_believes_valid = 0;
+  routerinfo_t *old_router;
 
   tor_assert(msg);
 
@@ -1665,17 +1675,13 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg,
       rs->need_to_mirror = 0;
   });
 
-  /* If we have a router with this name, and the identity key is the same,
-   * choose the newer one. If the identity key has changed, and one of the
-   * routers is named, drop the unnamed ones. (If more than one are named,
-   * drop the old ones.)
-   */
-  for (i = 0; i < smartlist_len(routerlist->routers); ++i) {
-    routerinfo_t *old_router = smartlist_get(routerlist->routers, i);
-    /* XXXX This might be a slow point; can't we just look up in one of the
-     * digestmaps? -NM */
-    if (!memcmp(router->cache_info.identity_digest,
-                old_router->cache_info.identity_digest, DIGEST_LEN)) {
+  /* If we have a router with the same identity key, choose the newer one. */
+  old_router = digestmap_get(routerlist->identity_map,
+                             router->cache_info.identity_digest);
+  if (old_router) {
+    int pos = old_router->routerlist_index;
+    tor_assert(smartlist_get(routerlist->routers, pos) == old_router);
+
     if (router->cache_info.published_on <=
         old_router->cache_info.published_on) {
       /* Same key, but old */
@@ -1719,7 +1725,7 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg,
           router->num_unreachable_notifications++;
         }
       }
-        routerlist_replace(routerlist, old_router, router, i, 1);
+      routerlist_replace(routerlist, old_router, router, pos, 1);
       if (!from_cache) {
         router_append_to_journal(&router->cache_info);
       }
@@ -1730,6 +1736,30 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg,
          "server as unapproved.)");
       return unreachable ? 1 : 0;
     }
+  }
+
+#if 1
+  /* XXXX This block is slow, and could be smarter.  All it does is ensure
+   * that if we have a named server called "Foo", we will never have another
+   * server called "Foo."  router_get_by_nickname() already knows to prefer
+   * named routers, so the problem only arises when there is a named router
+   * called 'foo', but we don't have it.  If, instead, we kept a
+   * name-to-identity-key mapping for each named router in the networkstatus
+   * list, we could eliminate this block.
+   *
+   * Hm. perhaps we should; I don't see how this code is non-broken wrt named
+   * routers. -NM
+   */
+
+  /* If the identity key has changed, and one of the
+   * routers is named, drop the unnamed ones. (If more than one are named,
+   * drop the old ones.)
+   */
+  for (i = 0; i < smartlist_len(routerlist->routers); ++i) {
+    routerinfo_t *old_router = smartlist_get(routerlist->routers, i);
+    if (!memcmp(router->cache_info.identity_digest,
+                old_router->cache_info.identity_digest, DIGEST_LEN)) {
+
     } else if (!strcasecmp(router->nickname, old_router->nickname)) {
       /* nicknames match, keys don't. */
       if (router->is_named) {
@@ -1760,6 +1790,8 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg,
       }
     }
   }
+#endif
+
   /* We haven't seen a router with this name before.  Add it to the end of
    * the list. */
   routerlist_insert(routerlist, router);
@@ -3970,6 +4002,7 @@ routerlist_assert_ok(routerlist_t *rl)
     sd2 = digestmap_get(rl->desc_digest_map,
                         r->cache_info.signed_descriptor_digest);
     tor_assert(&(r->cache_info) == sd2);
+    tor_assert(r->routerlist_index == r_sl_idx);
   });
   SMARTLIST_FOREACH(rl->old_routers, signed_descriptor_t *, sd,
   {

src/or/routerparse.c

@@ -752,6 +752,7 @@ router_parse_entry_from_string(const char *s, const char *end,
   }
 
   router = tor_malloc_zero(sizeof(routerinfo_t));
+  router->routerlist_index = -1;
   if (cache_copy)
     router->cache_info.signed_descriptor_body = tor_strndup(s, end-s);
   router->cache_info.signed_descriptor_len = end-s;