Squid-2.3.DEVEL2: ICP timeout selection
    This is an attempt to fix the dynamic ICP timeout selection when one is
    peering with remote parents and have some close-by siblings with a much
    lower ICP rtt. This is done by preferring to calculate the ICP timeout
    based on parents only (based on siblings if there is no alive parents)

Index: squid/src/neighbors.c
diff -u squid/src/neighbors.c:1.1.1.34.2.3 squid/src/neighbors.c:1.1.1.34.2.4
--- squid/src/neighbors.c:1.1.1.34.2.3	Sat Aug  7 19:42:13 1999
+++ squid/src/neighbors.c	Sat Aug  7 19:57:48 1999
@@ -374,6 +374,8 @@
     icp_common_t *query;
     int queries_sent = 0;
     int peers_pinged = 0;
+    int parent_timeout = 0, parent_exprep = 0;
+    int sibling_timeout = 0, sibling_exprep = 0;
 
     if (Config.peers == NULL)
 	return 0;
@@ -383,7 +385,6 @@
     mem->start_ping = current_time;
     mem->ping_reply_callback = callback;
     mem->ircb_data = callback_data;
-    *timeout = 0.0;
     reqnum = icpSetCacheKey(entry->key);
     for (i = 0, p = first_ping; i++ < Config.npeers; p = p->next) {
 	if (p == NULL)
@@ -438,8 +439,13 @@
 	    (*exprep) += p->mcast.n_replies_expected;
 	} else if (neighborUp(p)) {
 	    /* its alive, expect a reply from it */
-	    (*exprep)++;
-	    (*timeout) += p->stats.rtt;
+	    if (neighborType(p, request) == PEER_PARENT) {
+		parent_exprep++;
+		parent_timeout += p->stats.rtt;
+	    } else {
+		sibling_exprep++;
+		sibling_timeout += p->stats.rtt;
+	    }
 	} else {
 	    /* Neighbor is dead; ping it anyway, but don't expect a reply */
 	    /* log it once at the threshold */
@@ -489,14 +495,22 @@
     }
 #endif
     /*
+     * How many replies to expect?
+     */
+    *exprep = parent_exprep + sibling_exprep;
+
+    /*
      * If there is a configured timeout, use it
      */
     if (Config.Timeout.icp_query)
 	*timeout = Config.Timeout.icp_query;
     else {
-	if (*exprep > 0)
-	    (*timeout) = 2 * (*timeout) / (*exprep);
-	else
+	if (*exprep > 0) {
+	    if (parent_exprep)
+		*timeout = 2 * parent_timeout / parent_exprep;
+	    else
+		*timeout = 2 * sibling_timeout / sibling_exprep;
+	} else
 	    *timeout = 2000;	/* 2 seconds */
 	if (Config.Timeout.icp_query_max)
 	    if (*timeout > Config.Timeout.icp_query_max)