| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.tephra.distributed; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.tephra.TxConstants; |
| import org.apache.thrift.TException; |
| import org.apache.thrift.transport.TFramedTransport; |
| import org.apache.thrift.transport.TSocket; |
| import org.apache.thrift.transport.TTransport; |
| import org.apache.thrift.transport.TTransportException; |
| import org.apache.twill.discovery.Discoverable; |
| import org.apache.twill.discovery.DiscoveryServiceClient; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.Iterator; |
| import java.util.Random; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * An abstract tx client provider that implements common functionality. |
| */ |
| public abstract class AbstractClientProvider implements ThriftClientProvider { |
| |
| private static final Logger LOG = LoggerFactory.getLogger(AbstractClientProvider.class); |
| |
| // Discovery service. If null, no service discovery. |
| private final DiscoveryServiceClient discoveryServiceClient; |
| protected final AtomicBoolean initialized = new AtomicBoolean(false); |
| |
| // the configuration |
| final Configuration configuration; |
| |
| // the endpoint strategy for service discovery. |
| EndpointStrategy endpointStrategy; |
| |
| protected AbstractClientProvider(Configuration configuration, DiscoveryServiceClient discoveryServiceClient) { |
| this.configuration = configuration; |
| this.discoveryServiceClient = discoveryServiceClient; |
| } |
| |
| public void initialize() throws TException { |
| if (initialized.compareAndSet(false, true)) { |
| this.initDiscovery(); |
| } |
| } |
| |
| /** |
| * Initialize the service discovery client, we will reuse that |
| * every time we need to create a new client. |
| */ |
| private void initDiscovery() { |
| if (discoveryServiceClient == null) { |
| LOG.info("No DiscoveryServiceClient provided. Skipping service discovery."); |
| return; |
| } |
| |
| endpointStrategy = new TimeLimitEndpointStrategy( |
| new RandomEndpointStrategy( |
| discoveryServiceClient.discover( |
| configuration.get(TxConstants.Service.CFG_DATA_TX_DISCOVERY_SERVICE_NAME, |
| TxConstants.Service.DEFAULT_DATA_TX_DISCOVERY_SERVICE_NAME))), |
| 2, TimeUnit.SECONDS); |
| } |
| |
| protected TransactionServiceThriftClient newClient() throws TException { |
| return newClient(-1); |
| } |
| |
| protected TransactionServiceThriftClient newClient(int timeout) throws TException { |
| initialize(); |
| String address; |
| int port; |
| |
| if (endpointStrategy == null) { |
| // if there is no discovery service, try to read host and port directly |
| // from the configuration |
| LOG.info("Reading address and port from configuration."); |
| address = configuration.get(TxConstants.Service.CFG_DATA_TX_BIND_ADDRESS, |
| TxConstants.Service.DEFAULT_DATA_TX_BIND_ADDRESS); |
| port = configuration.getInt(TxConstants.Service.CFG_DATA_TX_BIND_PORT, |
| TxConstants.Service.DEFAULT_DATA_TX_BIND_PORT); |
| LOG.info("Service assumed at " + address + ":" + port); |
| } else { |
| Discoverable endpoint = endpointStrategy.pick(); |
| if (endpoint == null) { |
| LOG.error("Unable to discover tx service."); |
| throw new TException("Unable to discover tx service."); |
| } |
| address = endpoint.getSocketAddress().getHostName(); |
| port = endpoint.getSocketAddress().getPort(); |
| LOG.info("Service discovered at " + address + ":" + port); |
| } |
| |
| // now we have an address and port, try to connect a client |
| if (timeout < 0) { |
| timeout = configuration.getInt(TxConstants.Service.CFG_DATA_TX_CLIENT_TIMEOUT, |
| TxConstants.Service.DEFAULT_DATA_TX_CLIENT_TIMEOUT_MS); |
| } |
| LOG.info("Attempting to connect to tx service at " + |
| address + ":" + port + " with timeout " + timeout + " ms."); |
| // thrift transport layer |
| TTransport transport = |
| new TFramedTransport(new TSocket(address, port, timeout)); |
| try { |
| transport.open(); |
| } catch (TTransportException e) { |
| LOG.error("Unable to connect to tx service: " + e.getMessage()); |
| throw e; |
| } |
| // and create a thrift client |
| TransactionServiceThriftClient newClient = new TransactionServiceThriftClient(transport); |
| |
| LOG.info("Connected to tx service at " + |
| address + ":" + port); |
| return newClient; |
| } |
| |
| /** |
| * This class helps picking up an endpoint from a list of Discoverable. |
| */ |
| public interface EndpointStrategy { |
| |
| /** |
| * Picks a {@link Discoverable} using its strategy. |
| * @return A {@link Discoverable} based on the stragegy or {@code null} if no endpoint can be found. |
| */ |
| Discoverable pick(); |
| } |
| |
| /** |
| * An {@link EndpointStrategy} that make sure it picks an endpoint within the given |
| * timeout limit. |
| */ |
| public final class TimeLimitEndpointStrategy implements EndpointStrategy { |
| |
| private final EndpointStrategy delegate; |
| private final long timeout; |
| private final TimeUnit timeoutUnit; |
| |
| public TimeLimitEndpointStrategy(EndpointStrategy delegate, long timeout, TimeUnit timeoutUnit) { |
| this.delegate = delegate; |
| this.timeout = timeout; |
| this.timeoutUnit = timeoutUnit; |
| } |
| |
| @Override |
| public Discoverable pick() { |
| Discoverable pick = delegate.pick(); |
| try { |
| long count = 0; |
| while (pick == null && count++ < timeout) { |
| timeoutUnit.sleep(1); |
| pick = delegate.pick(); |
| } |
| } catch (InterruptedException e) { |
| // Simply propagate the interrupt. |
| Thread.currentThread().interrupt(); |
| } |
| return pick; |
| } |
| } |
| |
| /** |
| * Randomly picks endpoint from the list of available endpoints. |
| */ |
| public final class RandomEndpointStrategy implements EndpointStrategy { |
| |
| private final Iterable<Discoverable> endpoints; |
| |
| /** |
| * Constructs a random endpoint strategy. |
| * @param endpoints Endpoints for the strategy to use. Note that this strategy will |
| * invoke {@link Iterable#iterator()} and traverse through it on |
| * every call to the {@link #pick()} method. One could leverage this |
| * behavior with the live {@link Iterable} as provided by |
| * {@link org.apache.twill.discovery.DiscoveryServiceClient#discover(String)} method. |
| */ |
| public RandomEndpointStrategy(Iterable<Discoverable> endpoints) { |
| this.endpoints = endpoints; |
| } |
| |
| @Override |
| public Discoverable pick() { |
| // Reservoir sampling |
| Discoverable result = null; |
| Iterator<Discoverable> itor = endpoints.iterator(); |
| Random random = new Random(); |
| int count = 0; |
| while (itor.hasNext()) { |
| Discoverable next = itor.next(); |
| if (random.nextInt(++count) == 0) { |
| result = next; |
| } |
| } |
| return result; |
| } |
| } |
| } |
| |