Implement a getxid method that doesn't require full resurrection

of zombie objects.

bin/varnishd/storage/storage_persistent_silo.c

@@ -365,6 +365,35 @@ smp_loaded_st(const struct smp_sc *sc, const struct smp_seg *sg,
 	return (0);
 }
 
+/*---------------------------------------------------------------------
+ * objcore methods for persistent objects
+ */
+
+static unsigned __match_proto__(getxid_f)
+smp_oc_getxid(struct worker *wrk, struct objcore *oc)
+{
+	struct object *o;
+	struct smp_seg *sg;
+	struct smp_object *so;
+
+	(void)wrk;
+	CHECK_OBJ_NOTNULL(oc, OBJCORE_MAGIC);
+
+	CAST_OBJ_NOTNULL(sg, oc->priv, SMP_SEG_MAGIC);
+	so = smp_find_so(sg, oc->priv2);
+
+	o = (void*)(sg->sc->base + so->ptr);
+	/*
+	 * The object may not be in this segment since we allocate it
+	 * In a separate operation than the smp_object.  We could check
+	 * that it is in a later segment, but that would be complicated.
+	 * XXX: For now, be happy if it is inside th silo
+	 */
+	ASSERT_PTR_IN_SILO(sg->sc, o);
+	CHECK_OBJ_NOTNULL(o, OBJECT_MAGIC);
+	return (o->xid);
+}
+
 /*---------------------------------------------------------------------
  * objcore methods for persistent objects
  */
@@ -506,6 +535,7 @@ smp_oc_getlru(const struct objcore *oc)
 }
 
 static struct objcore_methods smp_oc_methods = {
+	.getxid =		smp_oc_getxid,
 	.getobj =		smp_oc_getobj,
 	.updatemeta =		smp_oc_updatemeta,
 	.freeobj =		smp_oc_freeobj,