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Take ping time into account when performing peer selection.

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This commit is contained in:
Mike Hearn 2012-12-25 01:23:28 +00:00
parent 3197be51ea
commit 273548c863
1 changed files with 31 additions and 7 deletions
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38
core/src/main/java/com/google/bitcoin/core/PeerGroup.java
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@ -1100,8 +1100,26 @@ public class PeerGroup extends AbstractIdleService {
return freqHeights[s - 1];
}
private static class PeerAndPing implements Comparable<PeerAndPing> {
Peer peer;
long pingTime;
public int compareTo(PeerAndPing peerAndPing) {
if (pingTime < peerAndPing.pingTime)
return -1;
else if (pingTime == peerAndPing.pingTime)
return 0;
else
return 1;
}
}
/** Given a list of Peers, return a Peer to be used as the download peer. */
protected Peer selectDownloadPeer(List<Peer> origPeers) {
// Characteristics to select for in order of importance:
// - Chain height is reasonable (majority of nodes)
// - Highest protocol version (more likely to be maintained, have the features we want)
// - Ping time.
List<Peer> peers;
synchronized (origPeers) {
peers = new ArrayList<Peer>(origPeers);
@ -1114,17 +1132,23 @@ public class PeerGroup extends AbstractIdleService {
for (Peer peer : peers) {
if (peer.getBestHeight() == mostCommonChainHeight) candidates.add(peer);
}
// Of the candidates, find the highest protocol version.
// Of the candidates, find the highest protocol version. Snapshot their ping times (so they don't change
// whilst sorting) and then sort to find the lowest.
int highestVersion = 0;
Peer leadingCandidate = null;
for (Peer peer : candidates) {
int v = peer.getPeerVersionMessage().clientVersion;
if (v > highestVersion) {
highestVersion = v;
leadingCandidate = peer;
highestVersion = Math.max(peer.getPeerVersionMessage().clientVersion, highestVersion);
}
List<PeerAndPing> candidates2 = new ArrayList<PeerAndPing>();
for (Peer peer : candidates) {
if (peer.getPeerVersionMessage().clientVersion == highestVersion) {
PeerAndPing pap = new PeerAndPing();
pap.peer = peer;
pap.pingTime = peer.getPingTime();
candidates2.add(pap);
}
}
return leadingCandidate;
Collections.sort(candidates2);
return candidates2.get(0).peer;
}
private static class PeerGroupThreadFactory implements ThreadFactory {