[4.1] e0fd9ba Add a force_fresh parameter to VBT_Get

[Dag Haavi Finstad]

commit e0fd9ba67e5234b167214658ba83070cb1b5a3ed
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Mon Nov 27 16:26:04 2017 +0100

    Add a force_fresh parameter to VBT_Get
    
    Passing a nonzero value will force a fresh backend connection.

diff --git a/bin/varnishd/cache/cache_backend.c b/bin/varnishd/cache/cache_backend.c
index 905bb13..4133359 100644
--- a/bin/varnishd/cache/cache_backend.c
+++ b/bin/varnishd/cache/cache_backend.c
@@ -91,7 +91,7 @@ vbe_dir_getfd(struct worker *wrk, struct backend *bp, struct busyobj *bo)
 	bo->htc->doclose = SC_NULL;
 
 	FIND_TMO(connect_timeout, tmod, bo, bp);
-	vc = VBT_Get(bp->tcp_pool, tmod, bp, wrk);
+	vc = VBT_Get(bp->tcp_pool, tmod, bp, wrk, 0);
 	if (vc == NULL) {
 		// XXX: Per backend stats ?
 		VSC_C_main->backend_fail++;
diff --git a/bin/varnishd/cache/cache_backend.h b/bin/varnishd/cache/cache_backend.h
index 0bc73ed..d52f2da 100644
--- a/bin/varnishd/cache/cache_backend.h
+++ b/bin/varnishd/cache/cache_backend.h
@@ -126,7 +126,7 @@ int VBT_Open(const struct tcp_pool *tp, double tmo, const struct suckaddr **sa);
 void VBT_Recycle(const struct worker *, struct tcp_pool *, struct vbc **);
 void VBT_Close(struct tcp_pool *tp, struct vbc **vbc);
 struct vbc *VBT_Get(struct tcp_pool *, double tmo, const struct backend *,
-    struct worker *);
+    struct worker *, unsigned force_fresh);
 void VBT_Wait(struct worker *, struct vbc *);
 
 /* cache_vcl.c */
diff --git a/bin/varnishd/cache/cache_backend_tcp.c b/bin/varnishd/cache/cache_backend_tcp.c
index 8e9b660..882d087 100644
--- a/bin/varnishd/cache/cache_backend_tcp.c
+++ b/bin/varnishd/cache/cache_backend_tcp.c
@@ -354,7 +354,7 @@ VBT_Close(struct tcp_pool *tp, struct vbc **vbcp)
 
 struct vbc *
 VBT_Get(struct tcp_pool *tp, double tmo, const struct backend *be,
-    struct worker *wrk)
+    struct worker *wrk, unsigned force_fresh)
 {
 	struct vbc *vbc;
 
@@ -365,7 +365,7 @@ VBT_Get(struct tcp_pool *tp, double tmo, const struct backend *be,
 	Lck_Lock(&tp->mtx);
 	vbc = VTAILQ_FIRST(&tp->connlist);
 	CHECK_OBJ_ORNULL(vbc, VBC_MAGIC);
-	if (vbc == NULL || vbc->state == VBC_STATE_STOLEN)
+	if (force_fresh || vbc == NULL || vbc->state == VBC_STATE_STOLEN)
 		vbc = NULL;
 	else {
 		assert(vbc->tcp_pool == tp);