Introduce req.hash_always_miss (force cache miss) and req.hash_ignore_busy...

Introduce req.hash_always_miss (force cache miss) and req.hash_ignore_busy (ignore busy objects) variables available in vcl_fetch.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@5170 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache.h

@@ -379,6 +379,9 @@ struct sess {
 	int			esis;
 	int			disable_esi;
 
+	uint8_t			hash_ignore_busy;
+	uint8_t			hash_always_miss;
+
 	struct worker		*wrk;
 
 	socklen_t		sockaddrlen;

bin/varnishd/cache_center.c

@@ -268,6 +268,8 @@ cnt_done(struct sess *sp)
 	memset(&sp->acct_req, 0, sizeof sp->acct_req);
 
 	sp->t_req = NAN;
+	sp->hash_always_miss = 0;
+	sp->hash_ignore_busy = 0;
 
 	if (sp->fd >= 0 && sp->doclose != NULL) {
 		/*

bin/varnishd/cache_hash.c

@@ -402,8 +402,9 @@ HSH_Lookup(struct sess *sp, struct objhead **poh)
 	if (oc == NULL			/* We found no live object */
 	    && grace_oc != NULL		/* There is a grace candidate */
 	    && (busy_oc != NULL		/* Somebody else is already busy */
-	    || !VDI_Healthy(sp->t_req, sp->director, (uintptr_t)oh))) {
-					 /* Or it is impossible to fetch: */
+	    || !VDI_Healthy(sp->t_req, sp->director, (uintptr_t)oh))
+					/* Or it is impossible to fetch */
+	    && !sp->hash_ignore_busy) { /* And we've not been told to ignore busy */
 		o = grace_oc->obj;
 		CHECK_OBJ_NOTNULL(o, OBJECT_MAGIC);
 		if (o->ttl + HSH_Grace(sp->grace) >= sp->t_req)
@@ -415,18 +416,27 @@ HSH_Lookup(struct sess *sp, struct objhead **poh)
 		CHECK_OBJ_NOTNULL(o, OBJECT_MAGIC);
 		assert(oc->objhead == oh);
 
-		/* We found an object we like */
-		oc->refcnt++;
-		if (o->hits < INT_MAX)
-			o->hits++;
-		assert(oh->refcnt > 1);
-		Lck_Unlock(&oh->mtx);
-		assert(hash->deref(oh));
-		*poh = oh;
-		return (oc);
+		if(sp->hash_always_miss) {
+			if (o->ttl >= sp->t_req) {
+				o->ttl = sp->t_req - 1;
+				o->grace = HSH_Grace(sp->grace);
+				EXP_Rearm(o);
+			}
+			o = NULL;
+		} else {
+			/* We found an object we like */
+			oc->refcnt++;
+			if (o->hits < INT_MAX)
+				o->hits++;
+			assert(oh->refcnt > 1);
+			Lck_Unlock(&oh->mtx);
+			assert(hash->deref(oh));
+			*poh = oh;
+			return (oc);
+		}
 	}
 
-	if (busy_oc != NULL) {
+	if (busy_oc != NULL && !sp->hash_ignore_busy) {
 		/* There are one or more busy objects, wait for them */
 		if (sp->esis == 0)
 			VTAILQ_INSERT_TAIL(&oh->waitinglist, sp, list);

bin/varnishd/cache_vrt.c

@@ -736,6 +736,42 @@ VRT_r_req_xid(struct sess *sp)
 	return (p);
 }
 
+/*--------------------------------------------------------------------
+ * req.hash_ignore_busy
+ */
+
+void
+VRT_l_req_hash_ignore_busy(struct sess *sp, unsigned ignore_busy)
+{
+	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
+	sp->hash_ignore_busy = !!ignore_busy;
+}
+
+unsigned
+VRT_r_req_hash_ignore_busy(struct sess *sp)
+{
+	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
+	return sp->hash_ignore_busy;
+}
+
+/*--------------------------------------------------------------------
+ * req.hash_always_miss
+ */
+
+void
+VRT_l_req_hash_always_miss(struct sess *sp, unsigned always_miss)
+{
+	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
+	sp->hash_always_miss = !!always_miss;
+}
+
+unsigned
+VRT_r_req_hash_always_miss(struct sess *sp)
+{
+	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
+	return sp->hash_always_miss;
+}
+
 /*--------------------------------------------------------------------*/
 
 struct sockaddr *

bin/varnishtest/tests/c00037.vtc

+# $Id$
+
+test "Test req.hash_always_miss in vcl_recv"
+
+server s1 {
+        rxreq 
+        txresp -hdr "Inc: 1"
+        rxreq 
+        txresp -hdr "Inc: 2"
+} -start
+
+varnish v1 -vcl+backend { 
+	sub vcl_recv {
+		if (req.http.x-missit == "1") {
+			set req.hash_always_miss = true;
+		}
+	}
+	sub vcl_deliver {
+		if(obj.hits > 0) {
+			set resp.http.X-Cache = "HIT";
+		} else {
+			set resp.http.X-Cache = "MISS";
+		}
+	}
+ } -start 
+
+client c1 {
+	txreq -url "/"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Inc == "1"
+	txreq -url "/"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Inc == "1"
+	txreq -url "/" -hdr "x-missit: 1"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Inc == "2"
+	txreq -url "/"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Inc == "2"
+} -run

bin/varnishtest/tests/c00038.vtc

+# $Id$
+
+test "Test req.hash_ignore_busy in vcl_recv"
+
+server s1 {
+	rxreq 
+	sema r1 sync 2
+	delay 1
+	txresp -hdr "Server: 1"
+} -start
+
+server s2 {
+	rxreq
+	txresp -hdr "Server: 2"
+} -start
+
+varnish v1 -vcl+backend { 
+	sub vcl_recv {
+		if (req.http.x-ignorebusy == "1") {
+			set req.hash_ignore_busy = true;
+		}
+		if (req.http.x-client == "1") {
+			set req.backend = s1;
+		}
+		if (req.http.x-client == "2") {
+			set req.backend = s2;
+		}
+	}
+	sub vcl_deliver {
+		if(obj.hits > 0) {
+			set resp.http.X-Cache = "HIT";
+		} else {
+			set resp.http.X-Cache = "MISS";
+		}
+	}
+} -start 
+
+client c1 {
+	txreq -url "/" -hdr "x-client: 1"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Server == "1"
+} -start
+
+client c2 {
+    sema r1 sync 2
+	txreq -url "/" -hdr "x-client: 2" -hdr "x-ignorebusy: 1"
+	txreq -url "/" -hdr "x-client: 2"
+	rxresp
+	expect resp.status == 200
+	expect resp.http.Server == "2"
+} -start
+
+client c1 -wait
+client c2 -wait

doc/sphinx/reference/vcl.rst

@@ -514,6 +514,12 @@ req.backend.healthy
 req.http.header
   The corresponding HTTP header.
 
+req.hash_always_miss
+  Force a cache miss for this request.
+
+req.hash_ignore_busy
+  Ignore any busy object during cache lookup.
+
 The following variables are available while preparing a backend
 request (either for a cache miss or for pass or pipe mode):
 

lib/libvcl/generate.py

@@ -196,6 +196,18 @@ sp_variables = (
 		( ),
 		'const struct sess *'
 	),
+	('req.hash_ignore_busy',
+		'BOOL',
+		( 'recv',),
+		( 'recv',),
+		'struct sess *'
+	),
+	('req.hash_always_miss',
+		'BOOL',
+		( 'recv',),
+		( 'recv',),
+		'struct sess *'
+	),
 	('bereq.request',
 		'STRING',
 		( 'pipe', 'pass', 'miss', 'fetch',),