Change calling convention of HSH_Lookup() so the return value

is what major case we hit, and the returned obj/busyobj goes into
pointer arguments.

bin/varnishd/cache/cache_hash.c

@@ -327,8 +327,9 @@ hsh_insert_busyobj(struct worker *wrk, struct objhead *oh)
  *
  */
 
-struct objcore *
-HSH_Lookup(struct req *req, int wait_for_busy, int always_insert)
+enum lookup_e
+HSH_Lookup(struct req *req, struct objcore **ocp, struct busyobj **bop,
+    int wait_for_busy, int always_insert)
 {
 	struct worker *wrk;
 	struct objhead *oh;
@@ -338,6 +339,11 @@ HSH_Lookup(struct req *req, int wait_for_busy, int always_insert)
 	double exp_entered;
 	int busy_found;
 
+	AN(ocp);
+	*ocp = NULL;
+	AN(bop);
+	*bop = NULL;
+
 	CHECK_OBJ_NOTNULL(req, REQ_MAGIC);
 	wrk = req->wrk;
 	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
@@ -368,10 +374,10 @@ HSH_Lookup(struct req *req, int wait_for_busy, int always_insert)
 
 	if (always_insert) {
 		/* Insert new objcore in objecthead and release mutex */
-		oc = hsh_insert_busyobj(wrk, oh);
+		*ocp = hsh_insert_busyobj(wrk, oh);
 		/* NB: no deref of objhead, new object inherits reference */
 		Lck_Unlock(&oh->mtx);
-		return (oc);
+		return (HSH_MISS);
 	}
 
 	assert(oh->refcnt > 0);
@@ -448,7 +454,8 @@ HSH_Lookup(struct req *req, int wait_for_busy, int always_insert)
 		assert(HSH_DerefObjHead(&wrk->stats, &oh));
 		if (!cache_param->obj_readonly && o->hits < INT_MAX)
 			o->hits++;
-		return (oc);
+		*ocp = oc;
+		return (HSH_HIT);
 	}
 
 	if (busy_found) {
@@ -480,14 +487,14 @@ HSH_Lookup(struct req *req, int wait_for_busy, int always_insert)
 		 */
 		req->hash_objhead = oh;
 		Lck_Unlock(&oh->mtx);
-		return (NULL);
+		return (HSH_BUSY);
 	}
 
 	/* Insert (precreated) objcore in objecthead and release mutex */
-	oc = hsh_insert_busyobj(wrk, oh);
+	*ocp = hsh_insert_busyobj(wrk, oh);
 	/* NB: no deref of objhead, new object inherits reference */
 	Lck_Unlock(&oh->mtx);
-	return (oc);
+	return (HSH_MISS);
 }
 
 /*---------------------------------------------------------------------

bin/varnishd/cache/cache_req_fsm.c

@@ -740,6 +740,7 @@ cnt_lookup(struct worker *wrk, struct req *req)
 	struct object *o;
 	struct objhead *oh;
 	struct busyobj *bo;
+	enum lookup_e lr;
 
 	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
 	CHECK_OBJ_NOTNULL(req, REQ_MAGIC);
@@ -751,11 +752,11 @@ cnt_lookup(struct worker *wrk, struct req *req)
 	VRY_Prep(req);
 
 	AZ(req->objcore);
-	oc = HSH_Lookup(req,
+	lr = HSH_Lookup(req, &oc, &bo,
 	    req->esi_level == 0 ? 1 : 0,
 	    req->hash_always_miss ? 1 : 0
 	);
-	if (oc == NULL) {
+	if (lr == HSH_BUSY) {
 		/*
 		 * We lost the session to a busy object, disembark the
 		 * worker thread.   We return to STP_LOOKUP when the busy

bin/varnishd/hash/hash_slinger.h

@@ -30,6 +30,8 @@
 
 struct sess;
 struct req;
+struct objcore;
+struct busyobj;
 struct worker;
 struct object;
 
@@ -51,9 +53,19 @@ struct hash_slinger {
 	hash_deref_f		*deref;
 };
 
+enum lookup_e {
+	HSH_MISS,
+	HSH_BUSY,
+	HSH_HIT,
+	HSH_EXP,
+	HSH_EXPBUSY
+};
+
 /* cache_hash.c */
 void HSH_Cleanup(struct worker *w);
-struct objcore *HSH_Lookup(struct req *, int wait_for_busy, int always_insert);
+enum lookup_e HSH_Lookup(struct req *, struct objcore **, struct busyobj **,
+    int wait_for_busy, int always_insert);
+// struct objcore *HSH_Lookup(struct req *, int wait_for_busy, int always_insert);
 void HSH_Ref(struct objcore *o);
 void HSH_Drop(struct worker *, struct object **);
 void HSH_Init(const struct hash_slinger *slinger);