Withdraw backend VSC counters when VCL is cold

bin/varnishd/cache/cache_backend.c

@@ -332,10 +332,22 @@ VRT_event_vbe(VRT_CTX, enum vcl_event_e ev, const struct director *d,
 	assert(d->priv2 == vrt);
 
 	CAST_OBJ_NOTNULL(be, d->priv, BACKEND_MAGIC);
+	if (ev == VCL_EVENT_WARM) {
+		be->vsc = VSM_Alloc(sizeof *be->vsc,
+		    VSC_CLASS, VSC_type_vbe, be->display_name);
+		AN(be->vsc);
+	}
+
 	if (be->probe != NULL && ev == VCL_EVENT_WARM)
 		VBP_Control(be, 0);
+
 	if (be->probe != NULL && ev == VCL_EVENT_COLD)
 		VBP_Control(be, 1);
+
+	if (ev == VCL_EVENT_COLD) {
+		VSM_Free(be->vsc);
+		be->vsc = NULL;
+	}
 }
 
 void

bin/varnishd/cache/cache_backend_cfg.c

@@ -66,7 +66,7 @@ VBE_DeleteBackend(struct backend *b)
 	free(b->ipv4);
 	free(b->ipv6);
 	free(b->display_name);
-	VSM_Free(b->vsc);
+	AZ(b->vsc);
 	VBT_Rel(&b->tcp_pool);
 	Lck_Delete(&b->mtx);
 	FREE_OBJ(b);
@@ -97,8 +97,6 @@ VBE_AddBackend(const char *vcl, const struct vrt_backend *vb)
 	bprintf(buf, "%s.%s", vcl, vb->vcl_name);
 	REPLACE(b->display_name, buf);
 
-	b->vsc = VSM_Alloc(sizeof *b->vsc, VSC_CLASS, VSC_type_vbe, buf);
-
 	b->vcl_name =  vb->vcl_name;
 	b->ipv4_addr = vb->ipv4_addr;
 	b->ipv6_addr = vb->ipv6_addr;

bin/varnishd/cache/cache_backend_poll.c

@@ -260,8 +260,10 @@ vbp_has_poked(struct vbp_target *vt)
 		    vt->backend->vcl_name, logmsg, bits,
 		    vt->good, vt->probe.threshold, vt->probe.window,
 		    vt->last, vt->avg, vt->resp_buf);
-		if (!vt->disable)
+		if (!vt->disable) {
+			AN(vt->backend->vsc);
 			vt->backend->vsc->happy = vt->happy;
+		}
 	}
 	Lck_Unlock(&vt->mtx);
 }
@@ -457,6 +459,7 @@ VBP_Insert(struct backend *b, const struct vrt_backend_probe *p,
 	b->probe = vt;
 	VTAILQ_INSERT_TAIL(&vbp_list, vt, list);
 	Lck_New(&vt->mtx, lck_backend);
+	vt->disable = 1;
 
 	vt->tcp_pool = VBT_Ref(b->ipv4, b->ipv6);
 	AN(vt->tcp_pool);

bin/varnishtest/tests/v00043.vcl

 varnishtest "vcl.state coverage tests"
 
-server s1 {
+server s1 -repeat 20 {
 	rxreq
 	txresp
+	delay .2
+	close
 } -start
 
-varnish v1 -vcl+backend {} -start
-varnish v1 -vcl+backend {} 
+varnish v1 -vcl {
+	backend default {
+		.host = "${s1_addr}";
+		.probe = { .interval = 1s; .initial = 1;}
+	}
+} -start
 
-varnish v1 -cliok "param.set vcl_cooldown 5"
+varnish v1 -cliok "param.set vcl_cooldown 3"
 
-varnish v1 -cliok "vcl.list"
-varnish v1 -cliok "vcl.use vcl2"
-varnish v1 -cliok "vcl.list"
-delay 5
-varnish v1 -cliok "vcl.list"
-varnish v1 -cliok "vcl.state vcl1 warm"
-varnish v1 -cliok "vcl.list"
+# We only have one vcl yet
+varnish v1 -expect VBE.vcl1.default.happy > 0
+varnish v1 -expect !VBE.vcl2.default.happy
+varnish v1 -cliok "backend.list -p *.*"
+
+varnish v1 -vcl {
+	backend default {
+		.host = "${s1_addr}";
+		.probe = { .interval = 1s; .initial = 1;}
+	}
+}
+
+# Now we have two vcls (and run on the latest loaded)
+varnish v1 -expect VBE.vcl1.default.happy > 0
+varnish v1 -expect VBE.vcl2.default.happy > 0
+
+# Freeze the first VCL
+varnish v1 -cliok "vcl.state vcl1 cold"
+varnish v1 -expect !VBE.vcl1.default.happy
+
+# Set it auto should be a no-op
+varnish v1 -cliok "vcl.state vcl1 auto"
+varnish v1 -expect !VBE.vcl1.default.happy
+
+# Use it, and it should come alive
 varnish v1 -cliok "vcl.use vcl1"
+varnish v1 -expect VBE.vcl1.default.happy > 0
+varnish v1 -expect VBE.vcl2.default.happy > 0
+
+# and the unused one should go cold
+delay 4
+varnish v1 -expect !VBE.vcl2.default.happy 
+
+# Mark the used warm and use it the other
+varnish v1 -cliok "vcl.state vcl1 warm"
 varnish v1 -cliok "vcl.use vcl2"
-delay 5
-varnish v1 -cliok "vcl.list"
+delay 4
+varnish v1 -expect VBE.vcl2.default.happy > 0