From: Andre Noll <maan@systemlinux.org>
Date: Sat, 30 Mar 2013 21:30:54 +0000 (+0000)
Subject: btr: Simplify btr_node_status().
X-Git-Tag: v0.5.1~9^2
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=bcea04fa816d0c0eb5469af6117b1014de8f87ca;hp=072391fccbd052334dbd836d451f2be0a74a0685

btr: Simplify btr_node_status().

This changes btr_node_status() to check for errors before looking
at queue sizes. In certain cases this avoids to call the possibly
expensive btr_get_output_queue_size().

If no more input is going to arrive for an internal node whose output
queue is full, btr_node_status() now returns EOF immediately, which
is better than the previous scheme where we waited for the output
queue to become empty before returning EOF.
---

diff --git a/buffer_tree.c b/buffer_tree.c
index 84dc933a..56ab2b24 100644
--- a/buffer_tree.c
+++ b/buffer_tree.c
@@ -1203,21 +1203,20 @@ int btr_node_status(struct btr_node *btrn, size_t min_iqs,
 	size_t iqs;
 
 	assert(btrn);
-	if (type != BTR_NT_LEAF) {
-		if (btr_no_children(btrn))
-			return -E_BTR_NO_CHILD;
-		if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
-			return 0;
-	}
-	if (type != BTR_NT_ROOT) {
-		if (btr_eof(btrn))
-			return -E_BTR_EOF;
-		iqs = btr_get_input_queue_size(btrn);
-		if (iqs == 0) /* we have a parent, because not eof */
-			return 0;
-		if (iqs < min_iqs && !btr_no_parent(btrn))
-			return 0;
-	}
+	if (type != BTR_NT_LEAF && btr_no_children(btrn))
+		return -E_BTR_NO_CHILD;
+	if (type != BTR_NT_ROOT && btr_eof(btrn))
+		return -E_BTR_EOF;
+
+	if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
+		return 0;
+	if (type == BTR_NT_ROOT)
+		return 1;
+	iqs = btr_get_input_queue_size(btrn);
+	if (iqs == 0) /* we have a parent, because not eof */
+		return 0;
+	if (iqs < min_iqs && !btr_no_parent(btrn))
+		return 0;
 	return 1;
 }