[nft PATCH 4/4] segtree: Refactor ei_insert()

[Phil Sutter <phil@nwl.cc>]

With all simplifications in place, reorder the code to streamline it
further. Apart from making the second call to ei_lookup() conditional,
debug output is slightly enhanced.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 src/segtree.c | 63 +++++++++++++++++++++++----------------------------
 1 file changed, 28 insertions(+), 35 deletions(-)

diff --git a/src/segtree.c b/src/segtree.c
index 3c0989e76093a..edec9f4ebf174 100644
--- a/src/segtree.c
+++ b/src/segtree.c
@@ -192,48 +192,41 @@ static int ei_insert(struct list_head *msgs, struct seg_tree *tree,
 {
 	struct elementary_interval *lei, *rei;
 
-	/*
-	 * Lookup the intervals containing the left and right endpoints.
-	 */
 	lei = ei_lookup(tree, new->left);
-	rei = ei_lookup(tree, new->right);
-
-	if (segtree_debug(tree->debug_mask))
-		pr_gmp_debug("insert: [%Zx %Zx]\n", new->left, new->right);
-
-	if (lei != NULL && rei != NULL && lei == rei) {
-		if (!merge)
-			goto err;
-
-		ei_destroy(new);
+	if (lei == NULL) {
+		/* no overlaps, just add the new interval */
+		if (segtree_debug(tree->debug_mask))
+			pr_gmp_debug("insert: [%Zx %Zx]\n",
+				     new->left, new->right);
+		__ei_insert(tree, new);
 		return 0;
-	} else {
-		if (lei != NULL) {
-			if (!merge)
-				goto err;
-			/*
-			 * Left endpoint is within lei, adjust it so we have:
-			 *
-			 * [lei_left, new_right]
-			 */
-			if (segtree_debug(tree->debug_mask)) {
-				pr_gmp_debug("adjust left [%Zx %Zx]\n",
-					     lei->left, lei->right);
-			}
+	}
 
-			mpz_set(lei->right, new->right);
-			ei_destroy(new);
-			return 0;
-		}
+	if (!merge) {
+		errno = EEXIST;
+		return expr_binary_error(msgs, lei->expr, new->expr,
+					 "conflicting intervals specified");
 	}
 
-	__ei_insert(tree, new);
+	/* caller sorted intervals, so rei is either equal to lei or NULL */
+	rei = ei_lookup(tree, new->right);
+	if (rei != lei) {
+		/*
+		 * Left endpoint is within lei, adjust it so we have:
+		 *
+		 * [lei_left, new_right]
+		 */
+		if (segtree_debug(tree->debug_mask))
+			pr_gmp_debug("adjust right: [%Zx %Zx]\n",
+				     lei->left, lei->right);
+		mpz_set(lei->right, new->right);
+	} else if (segtree_debug(tree->debug_mask)) {
+		pr_gmp_debug("skip new: [%Zx %Zx] for old: [%Zx %Zx]\n",
+			     new->left, new->right, lei->left, lei->right);
+	}
 
+	ei_destroy(new);
 	return 0;
-err:
-	errno = EEXIST;
-	return expr_binary_error(msgs, lei->expr, new->expr,
-				 "conflicting intervals specified");
 }
 
 /*
-- 
2.24.1