Rip out all the old backend refcounting code, and make backends

unique objects for each VCL which instantiate them.  (Instead we
share TCP connection pools, which are a lot simpler)

Spotted one utterly trivial memory leak along the way.

bin/varnishd/cache/cache_backend.c

@@ -175,15 +175,18 @@ vbe_dir_finish(const struct director *d, struct worker *wrk,
 		VSLb(bo->vsl, SLT_BackendClose, "%d %s", bo->htc->vbc->fd,
 		    bp->display_name);
 		VBT_Close(bp->tcp_pool, &bo->htc->vbc);
-		VBE_DropRefConn(bp, &bo->acct);
+		Lck_Lock(&bp->mtx);
 	} else {
 		VSLb(bo->vsl, SLT_BackendReuse, "%d %s", bo->htc->vbc->fd,
 		    bp->display_name);
 		Lck_Lock(&bp->mtx);
 		VSC_C_main->backend_recycle++;
 		VBT_Recycle(bp->tcp_pool, &bo->htc->vbc);
-		VBE_DropRefLocked(bp, &bo->acct);
 	}
+#define ACCT(foo)	bp->vsc->foo += bo->acct.foo;
+#include "tbl/acct_fields_bereq.h"
+#undef ACCT
+	Lck_Unlock(&bp->mtx);
 	bo->htc->vbc = NULL;
 	bo->htc = NULL;
 }
@@ -356,7 +359,7 @@ VRT_fini_vbe(VRT_CTX, struct director **dp, const struct vrt_backend *vrt)
 	if (vrt->probe != NULL)
 		VBP_Remove(be, vrt->probe);
 
-	VBE_DropRefVcl(be);
+	VBE_Drop(be);
 	free(d->vcl_name);
 	FREE_OBJ(d);
 }

bin/varnishd/cache/cache_backend.h

@@ -61,11 +61,11 @@ struct backend {
 	int			refcount;
 	struct lock		mtx;
 
-	char			*vcl_name;
+	const char		*vcl_name;
 	char			*display_name;
-	char			*ipv4_addr;
-	char			*ipv6_addr;
-	char			*port;
+	const char		*ipv4_addr;
+	const char		*ipv6_addr;
+	const char		*port;
 
 	struct suckaddr		*ipv4;
 	struct suckaddr		*ipv6;
@@ -104,12 +104,9 @@ struct vbc {
 };
 
 /* cache_backend_cfg.c */
-void VBE_DropRefConn(struct backend *, const struct acct_bereq *);
-void VBE_DropRefVcl(struct backend *);
-void VBE_DropRefLocked(struct backend *b, const struct acct_bereq *);
+void VBE_Drop(struct backend *);
 unsigned VBE_Healthy(const struct backend *b, double *changed);
 struct backend *VBE_AddBackend(const struct vrt_backend *vb);
-void VBE_Poll(void);
 
 /* cache_backend_poll.c */
 void VBP_Insert(struct backend *b, struct vrt_backend_probe const *p,

bin/varnishd/cache/cache_backend_cfg.c

@@ -54,97 +54,24 @@ static VTAILQ_HEAD(, backend) backends = VTAILQ_HEAD_INITIALIZER(backends);
 /*--------------------------------------------------------------------
  */
 
-static void
-VBE_Nuke(struct backend *b)
+void
+VBE_Drop(struct backend *b)
 {
 
 	ASSERT_CLI();
+	CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
+
+	b->vsc->vcls--;
 	VTAILQ_REMOVE(&backends, b, list);
 	free(b->ipv4);
-	free(b->ipv4_addr);
 	free(b->ipv6);
-	free(b->ipv6_addr);
-	free(b->port);
+	free(b->display_name);
 	VSM_Free(b->vsc);
 	VBT_Rel(&b->tcp_pool);
 	FREE_OBJ(b);
 	VSC_C_main->n_backend--;
 }
 
-/*--------------------------------------------------------------------
- */
-
-void
-VBE_Poll(void)
-{
-	struct backend *b, *b2;
-
-	ASSERT_CLI();
-	VTAILQ_FOREACH_SAFE(b, &backends, list, b2) {
-		assert(
-			b->admin_health == ah_healthy ||
-			b->admin_health == ah_sick ||
-			b->admin_health == ah_probe
-		);
-		if (b->refcount == 0 && b->probe == NULL)
-			VBE_Nuke(b);
-	}
-}
-
-/*--------------------------------------------------------------------
- * Drop a reference to a backend.
- * The last reference must come from the watcher in the CLI thread,
- * as only that thread is allowed to clean up the backend list.
- */
-
-void
-VBE_DropRefLocked(struct backend *b, const struct acct_bereq *acct_bereq)
-{
-	int i;
-
-	CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
-	assert(b->refcount > 0);
-
-	if (acct_bereq != NULL) {
-#define ACCT(foo) \
-		b->vsc->foo += acct_bereq->foo;
-#include "tbl/acct_fields_bereq.h"
-#undef ACCT
-	}
-
-	i = --b->refcount;
-	Lck_Unlock(&b->mtx);
-	if (i > 0)
-		return;
-
-	ASSERT_CLI();
-	VBE_Nuke(b);
-}
-
-void
-VBE_DropRefVcl(struct backend *b)
-{
-
-	CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
-
-	Lck_Lock(&b->mtx);
-	b->vsc->vcls--;
-	VBE_DropRefLocked(b, NULL);
-}
-
-void
-VBE_DropRefConn(struct backend *b, const struct acct_bereq *acct_bereq)
-{
-
-	CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
-
-	Lck_Lock(&b->mtx);
-	assert(b->n_conn > 0);
-	b->n_conn--;
-	b->vsc->conn--;
-	VBE_DropRefLocked(b, acct_bereq);
-}
-
 /*--------------------------------------------------------------------
  * Add a backend/director instance when loading a VCL.
  * If an existing backend is matched, grab a refcount and return.
@@ -161,27 +88,10 @@ VBE_AddBackend(const struct vrt_backend *vb)
 	AN(vb->vcl_name);
 	assert(vb->ipv4_suckaddr != NULL || vb->ipv6_suckaddr != NULL);
 
-	/* Run through the list and see if we already have this backend */
-	VTAILQ_FOREACH(b, &backends, list) {
-		CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
-		if (strcmp(b->vcl_name, vb->vcl_name))
-			continue;
-		if (vb->ipv4_suckaddr != NULL &&
-		    VSA_Compare(b->ipv4, vb->ipv4_suckaddr))
-			continue;
-		if (vb->ipv6_suckaddr != NULL &&
-		    VSA_Compare(b->ipv6, vb->ipv6_suckaddr))
-			continue;
-		b->refcount++;
-		b->vsc->vcls++;
-		return (b);
-	}
-
 	/* Create new backend */
 	ALLOC_OBJ(b, BACKEND_MAGIC);
 	XXXAN(b);
 	Lck_New(&b->mtx, lck_backend);
-	b->refcount = 1;
 
 	bprintf(buf, "%s(%s,%s,%s)",
 	    vb->vcl_name,
@@ -191,16 +101,11 @@ VBE_AddBackend(const struct vrt_backend *vb)
 	b->vsc = VSM_Alloc(sizeof *b->vsc, VSC_CLASS, VSC_type_vbe, buf);
 	b->vsc->vcls++;
 
-
-	/*
-	 * This backend may live longer than the VCL that instantiated it
-	 * so we cannot simply reference the VCL's copy of things.
-	 */
-	REPLACE(b->vcl_name, vb->vcl_name);
+	b->vcl_name =  vb->vcl_name;
 	REPLACE(b->display_name, buf);
-	REPLACE(b->ipv4_addr, vb->ipv4_addr);
-	REPLACE(b->ipv6_addr, vb->ipv6_addr);
-	REPLACE(b->port, vb->port);
+	b->ipv4_addr = vb->ipv4_addr;
+	b->ipv6_addr = vb->ipv6_addr;
+	b->port = vb->port;
 
 	b->tcp_pool = VBT_Ref(vb->vcl_name,
 	    vb->ipv4_suckaddr, vb->ipv6_suckaddr);
@@ -365,7 +270,7 @@ do_list(struct cli *cli, struct backend *b, void *priv)
 	}
 	CHECK_OBJ_NOTNULL(b, BACKEND_MAGIC);
 
-	VCLI_Out(cli, "\n%-30s %-6d", b->display_name, b->refcount);
+	VCLI_Out(cli, "\n%-30s", b->display_name);
 
 	if (b->admin_health == ah_probe)
 		VCLI_Out(cli, " %-10s", "probe");

bin/varnishd/cache/cache_cli.c

@@ -39,7 +39,6 @@
 #include "cache.h"
 #include "common/heritage.h"
 
-#include "cache_backend.h"		// struct vbc
 #include "vcli.h"
 #include "vcli_common.h"
 #include "vcli_priv.h"
@@ -79,7 +78,6 @@ cli_cb_before(const struct cli *cli)
 	ASSERT_CLI();
 	VSL(SLT_CLI, 0, "Rd %s", cli->cmd);
 	VCL_Poll();
-	VBE_Poll();
 	Lck_Lock(&cli_mtx);
 }