subtle change to avoid some false positives:

if a server went down for six hours and then came back, we would
complain to it that it's unreachable. now we wait until the third
consecutive descriptor post that we thought it was unreachable,
before complaining to it.


svn:r4891

src/or/dirserv.c

@@ -1290,6 +1290,7 @@ dirserv_orconn_tls_done(const char *address,
     } else { /* correct nickname and digest. mark this router reachable! */
       log_fn(LOG_INFO,"Found router %s to be reachable. Yay.", ri->nickname);
       ri->last_reachable = time(NULL);
+      ri->num_unreachable_notifications = 0;
     }
   }
 }

src/or/or.h

@@ -750,8 +750,13 @@ typedef struct {
 
   /* The below items are used only by authdirservers for
    * reachability testing. */
-  time_t last_reachable; /**< When was the last time we could reach this OR? */
-  time_t testing_since; /**< When did we start testing reachability for this OR? */
+  /** When was the last time we could reach this OR? */
+  time_t last_reachable;
+  /** When did we start testing reachability for this OR? */
+  time_t testing_since;
+  /** 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;
 } routerinfo_t;
 
 /** Contents of a running-routers list */

src/or/routerlist.c

@@ -912,7 +912,7 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg)
         *msg = "Router descriptor was not new.";
         return -1;
       } else {
-        int unreachable;
+        int unreachable = 0;
         log_fn(LOG_DEBUG, "Replacing entry for router '%s/%s' [%s]",
                router->nickname, old_router->nickname,
                hex_str(id_digest,DIGEST_LEN));
@@ -921,13 +921,20 @@ router_add_to_routerlist(routerinfo_t *router, const char **msg)
           /* these carry over when the address and orport are unchanged.*/
           router->last_reachable = old_router->last_reachable;
           router->testing_since = old_router->testing_since;
+          router->num_unreachable_notifications =
+             old_router->num_unreachable_notifications;
         }
-        unreachable = authdir &&
-          dirserv_thinks_router_is_blatantly_unreachable(router, time(NULL));
-        if (unreachable) {
-          log_fn(LOG_WARN, "Notifying server '%s' that it's unreachable. (ContactInfo '%s', platform '%s').",
-           router->nickname, router->contact_info ? router->contact_info : "",
-           router->platform ? router->platform : "");
+        if (authdir &&
+            dirserv_thinks_router_is_blatantly_unreachable(router, time(NULL))) {
+          if (router->num_unreachable_notifications >= 3) {
+            unreachable = 1;
+            log_fn(LOG_WARN, "Notifying server '%s' that it's unreachable. (ContactInfo '%s', platform '%s').",
+              router->nickname, router->contact_info ? router->contact_info : "",
+              router->platform ? router->platform : "");
+          } else {
+            log_fn(LOG_NOTICE,"'%s' may be unreachable -- the %d previous descriptors were thought to be unreachable.", router->nickname, router->num_unreachable_notifications);
+            router->num_unreachable_notifications++;
+          }
         }
         routerinfo_free(old_router);
         smartlist_set(routerlist->routers, i, router);