From 90c7ec80fffbd7b97c67bf7f7fd0486bec38a8c2 Mon Sep 17 00:00:00 2001
From: Mike Hearn <hearn@google.com>
Date: Thu, 21 Apr 2011 06:07:43 +0000
Subject: [PATCH] Replace for loop with an iterator to make the removal case
 clearer. Extend the unit test a bit.

This code will all be changing more in future anyway.
---
 src/com/google/bitcoin/core/BlockChain.java       | 14 +++++++-------
 tests/com/google/bitcoin/core/BlockChainTest.java |  7 +++++--
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/com/google/bitcoin/core/BlockChain.java b/src/com/google/bitcoin/core/BlockChain.java
index 9a6bafc81..c4d7c184b 100644
--- a/src/com/google/bitcoin/core/BlockChain.java
+++ b/src/com/google/bitcoin/core/BlockChain.java
@@ -16,10 +16,10 @@
 
 package com.google.bitcoin.core;
 
-import java.io.File;
 import java.math.BigInteger;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Iterator;
 
 import static com.google.bitcoin.core.Utils.LOG;
 
@@ -186,13 +186,14 @@ public class BlockChain {
      */
     private void tryConnectingUnconnected() throws VerificationException, ScriptException, BlockStoreException {
         // For each block in our unconnected list, try and fit it onto the head of the chain. If we succeed remove it
-        // from the list and keep going. If we changed the head of the list at the end of the round,
-        // try again until we can't fit anything else on the top.
+        // from the list and keep going. If we changed the head of the list at the end of the round try again until
+        // we can't fit anything else on the top.
         int blocksConnectedThisRound;
         do {
             blocksConnectedThisRound = 0;
-            for (int i = 0; i < unconnectedBlocks.size(); i++) {
-                Block block = unconnectedBlocks.get(i);
+            Iterator<Block> iter = unconnectedBlocks.iterator();
+            while (iter.hasNext()) {
+                Block block = iter.next();
                 // Look up the blocks previous.
                 StoredBlock prev = blockStore.get(block.getPrevBlockHash());
                 if (prev == null) {
@@ -202,8 +203,7 @@ public class BlockChain {
                 // Otherwise we can connect it now.
                 // False here ensures we don't recurse infinitely downwards when connecting huge chains.
                 add(block, false);
-                unconnectedBlocks.remove(i);
-                i--;  // The next iteration of the for loop will make "i" point to the right index again.
+                iter.remove();
                 blocksConnectedThisRound++;
             }
             if (blocksConnectedThisRound > 0) {
diff --git a/tests/com/google/bitcoin/core/BlockChainTest.java b/tests/com/google/bitcoin/core/BlockChainTest.java
index 7c739f493..32c3bde9d 100644
--- a/tests/com/google/bitcoin/core/BlockChainTest.java
+++ b/tests/com/google/bitcoin/core/BlockChainTest.java
@@ -25,7 +25,6 @@ import java.math.BigInteger;
 import static org.junit.Assert.*;
 
 // Tests still to write:
-//   - Rest of checkDifficultyTransitions: verify we don't accept invalid transitions.
 //   - Fragmented chains can be joined together.
 //   - Longest testNetChain is selected based on total difficulty not length.
 //   - Many more ...
@@ -78,8 +77,12 @@ public class BlockChainTest {
         Block b3 = b2.createNextBlock(coinbaseTo);
         // Connected.
         assertTrue(chain.add(b1));
-        // Unconnected.
+        // Unconnected but stored. The head of the chain is still b1.
         assertFalse(chain.add(b3));
+        assertEquals(chain.getChainHead().getHeader(), b1.cloneAsHeader());
+        // Add in the middle block.
+        assertTrue(chain.add(b2));
+        assertEquals(chain.getChainHead().getHeader(), b3.cloneAsHeader());
     }
 
     @Test