Make route operations execute in O(log n).

This changes the route table to be a sorted table of linked lists of
routes to a given prefix, which makes most route operations behave in
O(log n).  Insertion and flushing of a prefix is still O(n), but these
are fairly rare operations.

A nice side-effect is that the route table is now private to route.c,
which should make it easy to switch to a different data structure in
the future.

babeld.c

@@ -722,13 +722,8 @@ main(int argc, char **argv)
     usleep(roughly(10000));
     gettime(&now);
 
-    /* Uninstall and flush all routes. */
-    while(numroutes > 0) {
-        if(routes[0].installed)
-            uninstall_route(&routes[0]);
-        /* We need to flush the route so interface_up won't reinstall it */
-        flush_route(&routes[0]);
-    }
+    /* We need to flush so interface_up won't try to reinstall. */
+    flush_all_routes();
 
     FOR_ALL_INTERFACES(ifp) {
         if(!if_up(ifp))
@@ -923,6 +918,50 @@ init_signals(void)
 #endif
 }
 
+static void
+dump_route_callback(struct route *route, void *closure)
+{
+    FILE *out = (FILE*)closure;
+    const unsigned char *nexthop =
+        memcmp(route->nexthop, route->neigh->address, 16) == 0 ?
+        NULL : route->nexthop;
+    char channels[100];
+
+    if(route->channels[0] == 0)
+        channels[0] = '\0';
+    else {
+        int k, j = 0;
+        snprintf(channels, 100, " chan (");
+        j = strlen(channels);
+        for(k = 0; k < DIVERSITY_HOPS; k++) {
+            if(route->channels[k] == 0)
+                break;
+            if(k > 0)
+                channels[j++] = ',';
+            snprintf(channels + j, 100 - j, "%d", route->channels[k]);
+            j = strlen(channels);
+        }
+        snprintf(channels + j, 100 - j, ")");
+        if(k == 0)
+            channels[0] = '\0';
+    }
+
+    fprintf(out, "%s metric %d refmetric %d id %s seqno %d%s age %d "
+            "via %s neigh %s%s%s%s\n",
+            format_prefix(route->src->prefix, route->src->plen),
+            route_metric(route), route->refmetric,
+            format_eui64(route->src->id),
+            (int)route->seqno,
+            channels,
+            (int)(now.tv_sec - route->time),
+            route->neigh->ifp->name,
+            format_address(route->neigh->address),
+            nexthop ? " nexthop " : "",
+            nexthop ? format_address(nexthop) : "",
+            route->installed ? " (installed)" :
+            route_feasible(route) ? " (feasible)" : "");
+}
+
 static void
 dump_tables(FILE *out)
 {
@@ -948,45 +987,7 @@ dump_tables(FILE *out)
                 format_prefix(xroutes[i].prefix, xroutes[i].plen),
                 xroutes[i].metric);
     }
-    for(i = 0; i < numroutes; i++) {
-        const unsigned char *nexthop =
-            memcmp(routes[i].nexthop, routes[i].neigh->address, 16) == 0 ?
-            NULL : routes[i].nexthop;
-        char channels[100];
-        if(routes[i].channels[0] == 0)
-            channels[0] = '\0';
-        else {
-            int k, j = 0;
-            snprintf(channels, 100, " chan (");
-            j = strlen(channels);
-            for(k = 0; k < DIVERSITY_HOPS; k++) {
-                if(routes[i].channels[k] == 0)
-                    break;
-                if(k > 0)
-                    channels[j++] = ',';
-                snprintf(channels + j, 100 - j, "%d", routes[i].channels[k]);
-                j = strlen(channels);
-            }
-            snprintf(channels + j, 100 - j, ")");
-            if(k == 0)
-                channels[0] = '\0';
-        }
-
-        fprintf(out, "%s metric %d refmetric %d id %s seqno %d%s age %d "
-                "via %s neigh %s%s%s%s\n",
-                format_prefix(routes[i].src->prefix, routes[i].src->plen),
-                route_metric(&routes[i]), routes[i].refmetric,
-                format_eui64(routes[i].src->id),
-                (int)routes[i].seqno,
-                channels,
-                (int)(now.tv_sec - routes[i].time),
-                routes[i].neigh->ifp->name,
-                format_address(routes[i].neigh->address),
-                nexthop ? " nexthop " : "",
-                nexthop ? format_address(nexthop) : "",
-                routes[i].installed ? " (installed)" :
-                route_feasible(&routes[i]) ? " (feasible)" : "");
-    }
+    for_all_routes(dump_route_callback, out);
     fflush(out);
 }
 

local.c

@@ -222,6 +222,12 @@ local_notify_route(struct route *route, int kind)
     return;
 }
 
+static void
+local_notify_route_callback(struct route *route, void *closure)
+{
+    local_notify_route(route, LOCAL_ADD);
+}
+
 void
 local_notify_all()
 {
@@ -242,8 +248,7 @@ local_notify_all()
     }
     for(i = 0; i < numxroutes; i++)
         local_notify_xroute(&xroutes[i], LOCAL_ADD);
-    for(i = 0; i < numroutes; i++)
-        local_notify_route(&routes[i], LOCAL_ADD);
+    for_all_routes(local_notify_route_callback, NULL);
     return;
 
  fail:

message.c

@@ -1082,12 +1082,17 @@ buffer_update(struct interface *ifp,
     ifp->num_buffered_updates++;
 }
 
+void
+buffer_update_callback(struct route *route, void *closure)
+{
+    buffer_update((struct interface*)closure,
+                  route->src->prefix, route->src->plen);
+}
+
 void
 send_update(struct interface *ifp, int urgent,
             const unsigned char *prefix, unsigned char plen)
 {
-    int i;
-
     if(ifp == NULL) {
         struct interface *ifp_aux;
         struct route *route;
@@ -1118,11 +1123,7 @@ send_update(struct interface *ifp, int urgent,
             send_self_update(ifp);
             if(!parasitic) {
                 debugf("Sending update to %s for any.\n", ifp->name);
-                for(i = 0; i < numroutes; i++)
-                    if(routes[i].installed)
-                        buffer_update(ifp,
-                                      routes[i].src->prefix,
-                                      routes[i].src->plen);
+                for_all_installed_routes(buffer_update_callback, ifp);
             }
         }
         set_timeout(&ifp->update_timeout, ifp->update_interval);

route.h

 /*
-Copyright (c) 2007, 2008 by Juliusz Chroboczek
+Copyright (c) 2007-2011 by Juliusz Chroboczek
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -39,10 +39,10 @@ struct route {
     unsigned short hold_time;    /* in seconds */
     short installed;
     unsigned char channels[DIVERSITY_HOPS];
+    struct route *next;
 };
 
-extern struct route *routes;
-extern int numroutes, maxroutes;
+extern struct route **routes;
 extern int kernel_metric, allow_duplicates;
 extern int diversity_kind, diversity_factor;
 extern int keep_unfeasible;
@@ -70,8 +70,12 @@ struct route *find_route(const unsigned char *prefix, unsigned char plen,
 struct route *find_installed_route(const unsigned char *prefix,
                                    unsigned char plen);
 void flush_route(struct route *route);
+void flush_all_routes(void);
 void flush_neighbour_routes(struct neighbour *neigh);
 void flush_interface_routes(struct interface *ifp, int v4only);
+void for_all_routes(void (*f)(struct route*, void*), void *closure);
+void for_all_installed_routes(void (*f)(struct route*, void*), void *closure);
+struct route *find_route_with_source(struct source *src);
 void install_route(struct route *route);
 void uninstall_route(struct route *route);
 void switch_route(struct route *old, struct route *new);

source.c

@@ -46,8 +46,10 @@ find_source(const unsigned char *id, const unsigned char *p, unsigned char plen,
             continue;
         if(memcmp(src->id, id, 8) != 0)
             continue;
-        if(source_match(src, p, plen))
-           return src;
+        if(src->plen != plen)
+            continue;
+        if(memcmp(src->prefix, p, 16) == 0)
+            return src;
     }
 
     if(!create)
@@ -73,15 +75,10 @@ find_source(const unsigned char *id, const unsigned char *p, unsigned char plen,
 int
 flush_source(struct source *src)
 {
-    int i;
-
     /* This is absolutely horrible -- it makes expire_sources quadratic.
        But it's not called very often. */
-
-    for(i = 0; i < numroutes; i++) {
-        if(routes[i].src == src)
-            return 0;
-    }
+    if(find_route_with_source(src))
+        return 0;
 
     if(srcs == src) {
         srcs = src->next;
@@ -96,19 +93,6 @@ flush_source(struct source *src)
     return 1;
 }
 
-int
-source_match(struct source *src,
-             const unsigned char *p, unsigned char plen)
-{
-    if(src->plen != plen)
-        return 0;
-    if(src->prefix[15] != p[15])
-        return 0;
-    if(memcmp(src->prefix, p, 16) != 0)
-        return 0;
-    return 1;
-}
-
 void
 update_source(struct source *src,
               unsigned short seqno, unsigned short metric)

source.h

@@ -32,9 +32,6 @@ struct source {
     time_t time;
 };
 
-int source_match(struct source *src,
-                 const unsigned char *p, unsigned char plen)
-    ATTRIBUTE ((pure));
 struct source *find_source(const unsigned char *id,
                            const unsigned char *p,
                            unsigned char plen,