task #7497: Sort lists (pcb, netif, ...) for faster access UDP: move a (connected) pcb selected for input to the front of the list of pcbs so that it is found faster next time. Same for RAW pcbs that have eaten a packet.

CHANGELOG

@@ -19,6 +19,12 @@ HISTORY
 
   ++ New features:
 
+  2007-11-30 Simon Goldschmidt
+  * udp.c, raw.c: task #7497: Sort lists (pcb, netif, ...) for faster access
+    UDP: move a (connected) pcb selected for input to the front of the list of
+    pcbs so that it is found faster next time. Same for RAW pcbs that have eaten
+    a packet.
+
   2007-11-28 Simon Goldschmidt
   * etharp.c, stats.c, stats.h, opt.h: Introduced ETHARP_STATS
 

src/core/raw.c

@@ -77,7 +77,7 @@ static struct raw_pcb *raw_pcbs;
 u8_t
 raw_input(struct pbuf *p, struct netif *inp)
 {
-  struct raw_pcb *pcb;
+  struct raw_pcb *pcb, *prev;
   struct ip_hdr *iphdr;
   s16_t proto;
   u8_t eaten = 0;
@@ -87,6 +87,7 @@ raw_input(struct pbuf *p, struct netif *inp)
   iphdr = p->payload;
   proto = IPH_PROTO(iphdr);
 
+  prev = NULL;
   pcb = raw_pcbs;
   /* loop through all raw pcbs until the packet is eaten by one */
   /* this allows multiple pcbs to match against the packet by design */
@@ -100,11 +101,19 @@ raw_input(struct pbuf *p, struct netif *inp)
           /* receive function ate the packet */
           p = NULL;
           eaten = 1;
+          if (prev != NULL) {
+          /* move the pcb to the front of raw_pcbs so that is
+             found faster next time */
+            prev->next = pcb->next;
+            pcb->next = raw_pcbs;
+            raw_pcbs = pcb;
+          }
         }
       }
       /* no receive callback function was set for this raw PCB */
       /* drop the packet */
     }
+    prev = pcb;
     pcb = pcb->next;
   }
   return eaten;

src/core/udp.c

@@ -85,7 +85,7 @@ void
 udp_input(struct pbuf *p, struct netif *inp)
 {
   struct udp_hdr *udphdr;
-  struct udp_pcb *pcb;
+  struct udp_pcb *pcb, *prev;
   struct udp_pcb *uncon_pcb;
   struct ip_hdr *iphdr;
   u16_t src, dest;
@@ -149,6 +149,7 @@ udp_input(struct pbuf *p, struct netif *inp)
   } else
 #endif /* LWIP_DHCP */
   {
+    prev = NULL;
     local_match = 0;
     uncon_pcb = NULL;
     /* Iterate through the UDP pcb list for a matching pcb.
@@ -187,8 +188,18 @@ udp_input(struct pbuf *p, struct netif *inp)
           (ip_addr_isany(&pcb->remote_ip) ||
            ip_addr_cmp(&(pcb->remote_ip), &(iphdr->src)))) {
         /* the first fully matching PCB */
+        if (prev != NULL) {
+          /* move the pcb to the front of udp_pcbs so that is
+             found faster next time */
+          prev->next = pcb->next;
+          pcb->next = udp_pcbs;
+          udp_pcbs = pcb;
+        } else {
+          UDP_STATS_INC(udp.cachehit);
+        }
         break;
       }
+      prev = pcb;
     }
     /* no fully matching pcb found? then look for an unconnected pcb */
     if (pcb == NULL) {