document vslpdir_pick_be arguments

src/vslp_dir.c

@@ -383,6 +383,14 @@ vslpdir_any_healthy(struct vslpdir *vslpd)
 	return (retval);
 }
 
+/*
+ * hash: position on the ring
+ * n_retry:
+ *   0 : choose n-th backend based on number of restarts / retries
+ * >=1 : choose backend number n_retry (1= first)
+ * altsrv_p : use altsrv_p to use next backend
+ * healthy  : consider only healthy backends
+ */
 VCL_BACKEND vslpdir_pick_be(struct vslpdir *vslpd,
 		const struct vrt_ctx *ctx, uint32_t hash,
 		VCL_INT n_retry, VCL_BOOL altsrv_p, VCL_BOOL healthy)