From 71f8b25d3c22e599b57b33514dd1837f8ab73383 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Fri, 16 Jun 2017 00:04:26 -0700
Subject: [PATCH] chain: refactor getLocator.

---
 lib/blockchain/chain.js | 34 +++++++++++++---------------------
 1 file changed, 13 insertions(+), 21 deletions(-)

diff --git a/lib/blockchain/chain.js b/lib/blockchain/chain.js
index 0dd3c0ff..a3975da5 100644
--- a/lib/blockchain/chain.js
+++ b/lib/blockchain/chain.js
@@ -1844,7 +1844,7 @@ Chain.prototype.getLocator = co(function* getLocator(start) {
  * Calculate chain locator without a lock.
  * @method
  * @private
- * @param {Hash} start
+ * @param {Hash?} start
  * @returns {Promise}
  */
 
@@ -1860,10 +1860,8 @@ Chain.prototype._getLocator = co(function* getLocator(start) {
 
   entry = yield this.db.getEntry(start);
 
-  if (!entry) {
-    hashes.push(start);
-    entry = this.tip;
-  }
+  if (!entry)
+    throw new Error('Tip not found.');
 
   hash = entry.hash;
   height = entry.height;
@@ -1875,29 +1873,23 @@ Chain.prototype._getLocator = co(function* getLocator(start) {
     if (height === 0)
       break;
 
-    height = Math.max(0, height - step);
+    height -= step;
+
+    if (height < 0)
+      height = 0;
 
     if (hashes.length > 10)
       step *= 2;
 
-    if (height === 0) {
-      hash = this.network.genesis.hash;
-      continue;
-    }
-
-    // If we're on the main chain, we can
-    // do a fast lookup of the hash.
     if (main) {
+      // If we're on the main chain, we can
+      // do a fast lookup of the hash.
       hash = yield this.db.getHash(height);
-      continue;
+    } else {
+      entry = yield entry.getAncestor(height);
+      assert(entry);
+      hash = entry.hash;
     }
-
-    entry = yield entry.getAncestor(height);
-
-    if (!entry)
-      break;
-
-    hash = entry.hash;
   }
 
   return hashes;