private static void logState(
DegraderLoadBalancerState oldState,
DegraderLoadBalancerState newState,
DegraderLoadBalancerStrategyConfig config,
List<TrackerClientUpdater> trackerClientUpdaters) {
if (_log.isDebugEnabled()) {
_log.debug(
"Strategy updated: newState="
+ newState
+ ", config="
+ config
+ ", HashRing coverage="
+ newState.getRing());
} else {
if (!isOldStateTheSameAsNewState(oldState, newState)
|| !isNewStateHealthy(newState, config, trackerClientUpdaters)) {
_log.info(
"Strategy updated: newState="
+ newState
+ ", oldState ="
+ oldState
+ ", new state's config="
+ config);
}
}
}
@Override
public Ring<URI> getRing(
long clusterGenerationId, int partitionId, List<TrackerClient> trackerClients) {
if (partitionId != DEFAULT_PARTITION_ID) {
throw new UnsupportedOperationException(
"Trying to access partition: " + partitionId + "on an unpartitioned cluster");
}
checkUpdateState(clusterGenerationId, trackerClients);
return _state.getRing();
}
@Override
public TrackerClient getTrackerClient(
Request request,
RequestContext requestContext,
long clusterGenerationId,
int partitionId,
List<TrackerClient> trackerClients) {
if (partitionId != DEFAULT_PARTITION_ID) {
throw new UnsupportedOperationException(
"Trying to access partition: " + partitionId + "on an unpartitioned cluster");
}
debug(
_log,
"getTrackerClient with generation id ",
clusterGenerationId,
" on tracker clients: ",
clusterGenerationId);
if (trackerClients == null || trackerClients.size() == 0) {
warn(_log, "getTrackerClient called with null/empty trackerClients, so returning null");
return null;
}
// only one thread will be allowed to enter updateState.
checkUpdateState(clusterGenerationId, trackerClients);
URI targetHostUri = KeyMapper.TargetHostHints.getRequestContextTargetHost(requestContext);
URI hostHeaderUri = targetHostUri;
// no valid target host header was found in the request
if (targetHostUri == null) {
// Compute the hash code
int hashCode = _hashFunction.hash(request);
// we operate only on URIs to ensure that we never hold on to an old tracker client
// that the cluster manager has removed
targetHostUri = _state.getRing().get(hashCode);
} else {
debug(
_log,
"Degrader honoring target host header in request, skipping hashing. URI: "
+ targetHostUri.toString());
}
TrackerClient client = null;
if (targetHostUri != null) {
// These are the clients that were passed in, NOT necessarily the clients that make up the
// consistent hash ring! Therefore, this linear scan is the best we can do.
for (TrackerClient trackerClient : trackerClients) {
if (trackerClient.getUri().equals(targetHostUri)) {
client = trackerClient;
break;
}
}
if (client == null) {
warn(
_log,
"No client found for "
+ targetHostUri
+ (hostHeaderUri == null
? ", degrader load balancer state is inconsistent with cluster manager"
: ", target host specified is no longer part of cluster"));
}
} else {
warn(_log, "unable to find a URI to use");
}
boolean dropCall = client == null;
if (!dropCall) {
dropCall = client.getDegrader(DEFAULT_PARTITION_ID).checkDrop();
if (dropCall) {
warn(_log, "client's degrader is dropping call for: ", client);
} else {
debug(_log, "returning client: ", client);
}
}
return (!dropCall) ? client : null;
}
