/*
* Copyright © 2014 Cask Data, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package co.cask.cdap.common.guice;
import co.cask.cdap.common.conf.CConfiguration;
import co.cask.cdap.common.conf.Constants;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.inject.Inject;
import com.google.inject.name.Named;
import org.apache.twill.discovery.DiscoveryServiceClient;
import org.apache.twill.discovery.ServiceDiscovered;
import org.apache.twill.discovery.ZKDiscoveryService;
import org.apache.twill.zookeeper.ZKClient;
import org.apache.twill.zookeeper.ZKClients;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.TimeUnit;
/**
* A DiscoveryServiceClient implementation that will namespace correctly for program service discovery.
* Otherwise it'll delegate to default one.
*/
final class ProgramDiscoveryServiceClient implements DiscoveryServiceClient {
private static final Logger LOG = LoggerFactory.getLogger(ProgramDiscoveryServiceClient.class);
private static final long CACHE_EXPIRES_MINUTES = 1;
/**
* Defines the set of program types that are discoverable.
* TODO: We have program type in app-fabric, but here is common. Worth to refactor Type into one place.
*/
private enum DiscoverableProgramType {
PROCEDURE,
WORKFLOW,
WEBAPP,
SERVICE;
private final String prefix;
DiscoverableProgramType() {
prefix = name().toLowerCase() + ".";
}
boolean isPrefixOf(String name) {
return name.startsWith(prefix);
}
}
private final ZKClient zkClient;
private final DiscoveryServiceClient delegate;
private final String twillNamespace;
private final LoadingCache<String, DiscoveryServiceClient> clients;
@Inject
ProgramDiscoveryServiceClient(ZKClient zkClient,
CConfiguration configuration,
@Named("local.discovery.client") DiscoveryServiceClient delegate) {
this.zkClient = zkClient;
this.delegate = delegate;
this.twillNamespace = configuration.get(Constants.CFG_TWILL_ZK_NAMESPACE);
this.clients = CacheBuilder.newBuilder().expireAfterAccess(CACHE_EXPIRES_MINUTES, TimeUnit.MINUTES)
.build(createClientLoader());
}
@Override
public ServiceDiscovered discover(final String name) {
for (DiscoverableProgramType type : DiscoverableProgramType.values()) {
if (type.isPrefixOf(name)) {
return clients.getUnchecked(name).discover(name);
}
}
return delegate.discover(name);
}
private CacheLoader<String, DiscoveryServiceClient> createClientLoader() {
return new CacheLoader<String, DiscoveryServiceClient>() {
@Override
public DiscoveryServiceClient load(String key) throws Exception {
int idx = key.indexOf('.'); // It must be found as checked in the discover method
String ns = String.format("%s/%s%s", twillNamespace, key.substring(0, idx), key.substring(idx));
LOG.debug("Create ZKDiscoveryClient for " + ns);
return new ZKDiscoveryService(ZKClients.namespace(zkClient, ns));
}
};
}
}