From 5996da6a1d2eb11ac45d9d578618b9350e58593d Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sat, 13 Feb 1999 21:29:01 +0000
Subject: [PATCH] Implemented garbage collection of routing tables to delete
 orphaned network nodes having no routes attached. Such cleanup must be done
 from event handler since most functions manipulating the routing tables
 expect network entries won't disappear from under their hands and it's also
 probably faster when done asynchronously.

---
 nest/rt-table.c | 46 ++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 38 insertions(+), 8 deletions(-)

diff --git a/nest/rt-table.c b/nest/rt-table.c
index 73b679d5..621a8353 100644
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -14,11 +14,20 @@
 #include "nest/route.h"
 #include "nest/protocol.h"
 #include "lib/resource.h"
+#include "lib/event.h"
 
 rtable master_table;
 static slab *rte_slab;
 
-void
+#define RT_GC_MIN_TIME 5		/* FIXME: Make configurable */
+#define RT_GC_MIN_COUNT 100
+
+static pool *rt_table_pool;
+static event *rt_gc_event;
+static bird_clock_t rt_last_gc;
+static int rt_gc_counter;
+
+static void
 rte_init(struct fib_node *N)
 {
   net *n = (net *) N;
@@ -206,6 +215,8 @@ rte_update(net *net, struct proto *p, rte *new)
 		}
 	      r->next = net->routes;
 	      net->routes = r;
+	      if (!r && rt_gc_counter++ >= RT_GC_MIN_COUNT && rt_last_gc + RT_GC_MIN_TIME <= now)
+		ev_schedule(rt_gc_event);
 	    }
 	}
       if (new)				/* Link in the new non-optimal route */
@@ -280,19 +291,32 @@ rt_dump_all(void)
   rt_dump(&master_table);
 }
 
+static void
+rt_gc(void *unused)
+{
+  DBG("Entered routing table garbage collector after %d seconds and %d deletes\n", (int)(now - rt_last_gc), rt_gc_counter);
+  rt_prune(&master_table);
+  rt_last_gc = now;
+  rt_gc_counter = 0;
+}
+
 void
 rt_init(void)
 {
   rta_init();
+  rt_table_pool = rp_new(&root_pool, "Routing tables");
   rt_setup(&master_table, "master");
-  rte_slab = sl_new(&root_pool, sizeof(rte));
+  rte_slab = sl_new(rt_table_pool, sizeof(rte));
+  rt_last_gc = now;
+  rt_gc_event = ev_new(rt_table_pool);
+  rt_gc_event->hook = rt_gc;
 }
 
 void
 rt_prune(rtable *tab)
 {
   struct fib_iterator fit;
-  int cnt = 0;
+  int rcnt = 0, rdel = 0, ncnt = 0, ndel = 0;
 
   DBG("Pruning route table %s\n", tab->name);
   while (tab)
@@ -303,17 +327,23 @@ rt_prune(rtable *tab)
 	{
 	  net *n = (net *) f;
 	  rte *e;
-	  for (e=n->routes; e; e=e->next)
+	  ncnt++;
+	  for (e=n->routes; e; e=e->next, rcnt++)
 	    if (e->attrs->proto->core_state != FS_HAPPY)
 	      {
-		FIB_ITERATE_PUT(&fit, f);
 		rte_discard(e);
-		cnt++;
-		goto again;
+		rdel++;
 	      }
+	  if (!n->routes)		/* Orphaned FIB entry? */
+	    {
+	      FIB_ITERATE_PUT(&fit, f);
+	      fib_delete(&tab->fib, f);
+	      ndel++;
+	      goto again;
+	    }
 	}
       FIB_ITERATE_END(f);
       tab = tab->sibling;
     }
-  DBG("Pruned %d routes\n", cnt);
+  DBG("Pruned %d of %d routes and %d of %d networks\n", rcnt, rdel, ncnt, ndel);
 }