From: phk <phk@d4fa192b-c00b-0410-8231-f00ffab90ce4>
Date: Mon, 28 Jan 2008 09:09:12 +0000 (+0000)
Subject: Instead of sleeping as soon as we see a busy object, traverse the rest
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=426553907c07a0f741d66f524395c149f7d9ef6e;p=varnish

Instead of sleeping as soon as we see a busy object, traverse the rest
of the objects on the objecthead to see if there is anything we can use.

This unpessimizes Vary: processing, where we previously might go to sleep
on a busy object despite the fact that we have a good and valid object
with the Vary: we desire.



git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@2390 d4fa192b-c00b-0410-8231-f00ffab90ce4
---

diff --git a/varnish-cache/bin/varnishd/cache_hash.c b/varnish-cache/bin/varnishd/cache_hash.c
index df3fc007..eafa0852 100644
--- a/varnish-cache/bin/varnishd/cache_hash.c
+++ b/varnish-cache/bin/varnishd/cache_hash.c
@@ -173,7 +173,7 @@ HSH_Lookup(struct sess *sp)
 	struct worker *w;
 	struct http *h;
 	struct objhead *oh;
-	struct object *o;
+	struct object *o, *busy_o;
 
 	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
 	CHECK_OBJ_NOTNULL(sp->wrk, WORKER_MAGIC);
@@ -197,12 +197,11 @@ HSH_Lookup(struct sess *sp)
 		LOCK(&oh->mtx);
 	}
 
+	busy_o = NULL;
 	VTAILQ_FOREACH(o, &oh->objects, list) {
 		if (o->busy) {
-			VTAILQ_INSERT_TAIL(&oh->waitinglist, sp, list);
-			sp->objhead = oh;
-			UNLOCK(&oh->mtx);
-			return (NULL);
+			busy_o = o;
+			continue;
 		}
 		if (!o->cacheable)
 			continue;
@@ -221,12 +220,21 @@ HSH_Lookup(struct sess *sp)
 			break;
 	}
 	if (o != NULL) {
+		/* We found an object we like */
 		o->refcnt++;
 		UNLOCK(&oh->mtx);
 		(void)hash->deref(oh);
 		return (o);
 	}
 
+	if (busy_o != NULL) {
+		/* There are one or more busy objects, wait for them */
+		VTAILQ_INSERT_TAIL(&oh->waitinglist, sp, list);
+		sp->objhead = oh;
+		UNLOCK(&oh->mtx);
+		return (NULL);
+	}
+
 	/* Insert (precreated) object in objecthead */
 	o = w->nobj;
 	w->nobj = NULL;