mirrors/bitcoinj
1
0
Fork 0
mirror of https://github.com/bitcoinj/bitcoinj.git synced 2024-11-20 18:22:12 +01:00
Code Issues Packages Projects Releases Wiki Activity

Improve the block locator we send to remote peers as a temporary hack for the lack of exponential thinning. Patch from Jan. Updates issue 84.

Browse Source
This commit is contained in:
Mike Hearn 2011-10-21 09:57:59 +00:00
parent 0bc87e5804
commit d2e4284930
2 changed files with 19 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/com/google/bitcoin/core/Peer.java
View File

@ -358,12 +358,25 @@ public class Peer {
// TODO: Block locators should be abstracted out rather than special cased here.
List<Sha256Hash> blockLocator = new LinkedList<Sha256Hash>();
// We don't do the exponential thinning here, so if we get onto a fork of the chain we will end up
// redownloading the whole thing again.
// For now we don't do the exponential thinning as suggested here:
// https://en.bitcoin.it/wiki/Protocol_specification#getblocks
// However, this should be taken seriously going forward. The old implementation only added the hash of the
// genesis block and the current chain head, which randomly led us to halt block fetching when ending on a
// chain that turned out not to be the longest. This happened roughly once a week.
// Now we add three hashes to the locator:
// 1. Hash of genesis block
// 2. Hash of the block previous to the chain head
// 3. Hash of the chain head
// This allows our peer to see that we are on the wrong track if we ended up on the wrong side of a chain fork
// if the fork is only one block deep.
blockLocator.add(params.genesisBlock.getHash());
Block topBlock = blockChain.getChainHead().getHeader();
if (!topBlock.equals(params.genesisBlock))
if (!topBlock.equals(params.genesisBlock)) {
if (!topBlock.getPrevBlockHash().equals(params.genesisBlock)){
blockLocator.add(0, topBlock.getPrevBlockHash());
}
blockLocator.add(0, topBlock.getHash());
}
GetBlocksMessage message = new GetBlocksMessage(params, blockLocator, toHash);
conn.writeMessage(message);
}

3
tests/com/google/bitcoin/core/PeerTest.java
View File

@ -136,6 +136,7 @@ public class PeerTest {
List<Sha256Hash> expectedLocator = new ArrayList<Sha256Hash>();
expectedLocator.add(b1.getHash());
expectedLocator.add(b1.getPrevBlockHash());
expectedLocator.add(unitTestParams.genesisBlock.getHash());
assertEquals(message.getValue().getLocator(), expectedLocator);
@ -171,6 +172,7 @@ public class PeerTest {
List<Sha256Hash> expectedLocator = new ArrayList<Sha256Hash>();
expectedLocator.add(b1.getHash());
expectedLocator.add(b1.getPrevBlockHash());
expectedLocator.add(unitTestParams.genesisBlock.getHash());
assertEquals(message.getValue().getLocator(), expectedLocator);
@ -234,6 +236,7 @@ public class PeerTest {
List<Sha256Hash> expectedLocator = new ArrayList<Sha256Hash>();
expectedLocator.add(b1.getHash());
expectedLocator.add(b1.getPrevBlockHash());
expectedLocator.add(unitTestParams.genesisBlock.getHash());
assertEquals(message.getValue().getLocator(), expectedLocator);