Java tutorial
/* * 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.cassandra.gms; import java.io.*; import java.net.InetAddress; import java.util.Collection; import java.util.UUID; import static java.nio.charset.StandardCharsets.ISO_8859_1; import com.google.common.collect.Iterables; import org.apache.cassandra.db.TypeSizes; import org.apache.cassandra.dht.IPartitioner; import org.apache.cassandra.dht.Token; import org.apache.cassandra.io.IVersionedSerializer; import org.apache.cassandra.io.util.DataOutputPlus; import org.apache.cassandra.net.MessagingService; import org.apache.cassandra.utils.FBUtilities; import org.apache.commons.lang3.StringUtils; /** * This abstraction represents the state associated with a particular node which an * application wants to make available to the rest of the nodes in the cluster. * Whenever a piece of state needs to be disseminated to the rest of cluster wrap * the state in an instance of <i>ApplicationState</i> and add it to the Gossiper. * <p> * e.g. if we want to disseminate load information for node A do the following: * </p> * <pre> * {@code * ApplicationState loadState = new ApplicationState(<string representation of load>); * Gossiper.instance.addApplicationState("LOAD STATE", loadState); * } * </pre> */ public class VersionedValue implements Comparable<VersionedValue> { public static final IVersionedSerializer<VersionedValue> serializer = new VersionedValueSerializer(); // this must be a char that cannot be present in any token public final static char DELIMITER = ','; public final static String DELIMITER_STR = new String(new char[] { DELIMITER }); // values for ApplicationState.STATUS public final static String STATUS_BOOTSTRAPPING = "BOOT"; public final static String STATUS_NORMAL = "NORMAL"; public final static String STATUS_LEAVING = "LEAVING"; public final static String STATUS_LEFT = "LEFT"; public final static String STATUS_MOVING = "MOVING"; public final static String REMOVING_TOKEN = "removing"; public final static String REMOVED_TOKEN = "removed"; public final static String HIBERNATE = "hibernate"; public final static String SHUTDOWN = "shutdown"; // values for ApplicationState.REMOVAL_COORDINATOR public final static String REMOVAL_COORDINATOR = "REMOVER"; public final int version; public final String value; private VersionedValue(String value, int version) { assert value != null; // blindly interning everything is somewhat suboptimal -- lots of VersionedValues are unique -- // but harmless, and interning the non-unique ones saves significant memory. (Unfortunately, // we don't really have enough information here in VersionedValue to tell the probably-unique // values apart.) See CASSANDRA-6410. this.value = value.intern(); this.version = version; } private VersionedValue(String value) { this(value, VersionGenerator.getNextVersion()); } public int compareTo(VersionedValue value) { return this.version - value.version; } @Override public String toString() { return "Value(" + value + "," + version + ")"; } public byte[] toBytes() { return value.getBytes(ISO_8859_1); } private static String versionString(String... args) { return StringUtils.join(args, VersionedValue.DELIMITER); } public static class VersionedValueFactory { final IPartitioner partitioner; public VersionedValueFactory(IPartitioner partitioner) { this.partitioner = partitioner; } public VersionedValue cloneWithHigherVersion(VersionedValue value) { return new VersionedValue(value.value); } public VersionedValue bootstrapping(Collection<Token> tokens) { return new VersionedValue(versionString(VersionedValue.STATUS_BOOTSTRAPPING, makeTokenString(tokens))); } public VersionedValue normal(Collection<Token> tokens) { return new VersionedValue(versionString(VersionedValue.STATUS_NORMAL, makeTokenString(tokens))); } private String makeTokenString(Collection<Token> tokens) { return partitioner.getTokenFactory().toString(Iterables.get(tokens, 0)); } public VersionedValue load(double load) { return new VersionedValue(String.valueOf(load)); } public VersionedValue schema(UUID newVersion) { return new VersionedValue(newVersion.toString()); } public VersionedValue leaving(Collection<Token> tokens) { return new VersionedValue(versionString(VersionedValue.STATUS_LEAVING, makeTokenString(tokens))); } public VersionedValue left(Collection<Token> tokens, long expireTime) { return new VersionedValue( versionString(VersionedValue.STATUS_LEFT, makeTokenString(tokens), Long.toString(expireTime))); } public VersionedValue moving(Token token) { return new VersionedValue(VersionedValue.STATUS_MOVING + VersionedValue.DELIMITER + partitioner.getTokenFactory().toString(token)); } public VersionedValue hostId(UUID hostId) { return new VersionedValue(hostId.toString()); } public VersionedValue tokens(Collection<Token> tokens) { ByteArrayOutputStream bos = new ByteArrayOutputStream(); DataOutputStream out = new DataOutputStream(bos); try { TokenSerializer.serialize(partitioner, tokens, out); } catch (IOException e) { throw new RuntimeException(e); } return new VersionedValue(new String(bos.toByteArray(), ISO_8859_1)); } public VersionedValue removingNonlocal(UUID hostId) { return new VersionedValue(versionString(VersionedValue.REMOVING_TOKEN, hostId.toString())); } public VersionedValue removedNonlocal(UUID hostId, long expireTime) { return new VersionedValue( versionString(VersionedValue.REMOVED_TOKEN, hostId.toString(), Long.toString(expireTime))); } public VersionedValue removalCoordinator(UUID hostId) { return new VersionedValue(versionString(VersionedValue.REMOVAL_COORDINATOR, hostId.toString())); } public VersionedValue hibernate(boolean value) { return new VersionedValue(VersionedValue.HIBERNATE + VersionedValue.DELIMITER + value); } public VersionedValue rpcReady(boolean value) { return new VersionedValue(String.valueOf(value)); } public VersionedValue shutdown(boolean value) { return new VersionedValue(VersionedValue.SHUTDOWN + VersionedValue.DELIMITER + value); } public VersionedValue datacenter(String dcId) { return new VersionedValue(dcId); } public VersionedValue rack(String rackId) { return new VersionedValue(rackId); } public VersionedValue rpcaddress(InetAddress endpoint) { return new VersionedValue(endpoint.getHostAddress()); } public VersionedValue releaseVersion() { return new VersionedValue(FBUtilities.getReleaseVersionString()); } public VersionedValue networkVersion() { return new VersionedValue(String.valueOf(MessagingService.current_version)); } public VersionedValue internalIP(String private_ip) { return new VersionedValue(private_ip); } public VersionedValue severity(double value) { return new VersionedValue(String.valueOf(value)); } } private static class VersionedValueSerializer implements IVersionedSerializer<VersionedValue> { public void serialize(VersionedValue value, DataOutputPlus out, int version) throws IOException { out.writeUTF(outValue(value, version)); out.writeInt(value.version); } private String outValue(VersionedValue value, int version) { return value.value; } public VersionedValue deserialize(DataInput in, int version) throws IOException { String value = in.readUTF(); int valVersion = in.readInt(); return new VersionedValue(value, valVersion); } public long serializedSize(VersionedValue value, int version) { return TypeSizes.NATIVE.sizeof(outValue(value, version)) + TypeSizes.NATIVE.sizeof(value.version); } } }