public TrPeerInfo getPeerForAssimilation() {
if (peers.isEmpty()) {
// We need to use a public peer
final ArrayList<File> publicNodeIdFiles = node.getPublicNodeIdFiles();
final File pubPeerFile =
publicNodeIdFiles.get(TrUtils.rand.nextInt(publicNodeIdFiles.size()));
final TrPeerInfo pnii = Persistence.loadReadOnly(TrPeerInfo.class, pubPeerFile);
return pnii;
} else {
/**
* Here we use a trick to pick peers in proportion to the probability that they will be the
* fastest peer
*/
TrPeerInfo bestPeer = null;
double bestTimeEstimate = Double.MAX_VALUE;
final LinearStat globalSuccessTime = new LinearStat(Integer.MAX_VALUE);
globalSuccessTime.sample(1000);
globalSuccessTime.sample(2000);
for (final TrPeerInfo ifo : peers.values()) {
if (ifo.assimilation.successTimeSqrt.total > 0) {
globalSuccessTime.sample(ifo.assimilation.successTimeSqrt.mean());
}
}
for (final Entry<PhysicalNetworkLocation, TrPeerInfo> e : peers.entrySet()) {
final double guessFailureProb = e.getValue().assimilation.successRate.getBetaRandom();
double guessSuccessTime;
// If we don't have at least 2 samples, use our global success
// time
if (e.getValue().assimilation.successTimeSqrt.total > 2) {
final double guessSuccessTimeSqrt =
e.getValue().assimilation.successTimeSqrt.getNormalRandom();
guessSuccessTime = guessSuccessTimeSqrt * guessSuccessTimeSqrt;
} else {
final double guessSuccessTimeSqrt = globalSuccessTime.getNormalRandom();
guessSuccessTime = guessSuccessTimeSqrt * guessSuccessTimeSqrt;
}
double timeEstimate =
guessSuccessTime
+ AssimilateSessionImpl.RELAY_ASSIMILATION_TIMEOUT_SECONDS
* 1000l
* guessFailureProb;
if (lastAttemptedRelays.contains(e.getValue())) {
timeEstimate *= RECENTLY_ATTEMPTED_PENALTY;
}
if (timeEstimate < bestTimeEstimate) {
bestPeer = e.getValue();
bestTimeEstimate = timeEstimate;
}
}
lastAttemptedRelays.add(bestPeer);
while (lastAttemptedRelays.size() > 5) {
lastAttemptedRelays.poll();
}
return bestPeer;
}
}
/**
* If you need to modify a peer's information you must do it using this method, as it ensures that
* persistent peer information gets persisted
*
* @param addr
* @param updateFunction
*/
public void updatePeerInfo(
final PhysicalNetworkLocation addr, final Function<TrPeerInfo, Void> updateFunction) {
final File pubNodeFile = node.getFileForPublicNode(addr);
if (pubNodeFile.exists()) {
Persistence.loadAndModify(
TrPeerInfo.class,
pubNodeFile,
new Persistence.ModifyBlock<TrPeerInfo>() {
public void run(final TrPeerInfo object, final Modified modified) {
updateFunction.apply(object);
}
});
} else {
updateFunction.apply(peers.get(addr));
}
}
