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.transport.messages; import com.google.common.annotations.VisibleForTesting; import io.netty.buffer.ByteBuf; import org.apache.cassandra.cql3.ResultSet; import org.apache.cassandra.transport.*; import org.apache.cassandra.utils.MD5Digest; public abstract class ResultMessage extends Message.Response { public static final Message.Codec<ResultMessage> codec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { Kind kind = Kind.fromId(body.readInt()); return kind.subcodec.decode(body, version); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { dest.writeInt(msg.kind.id); msg.kind.subcodec.encode(msg, dest, version); } public int encodedSize(ResultMessage msg, ProtocolVersion version) { return 4 + msg.kind.subcodec.encodedSize(msg, version); } }; public enum Kind { VOID(1, Void.subcodec), ROWS(2, Rows.subcodec), SET_KEYSPACE(3, SetKeyspace.subcodec), PREPARED(4, Prepared.subcodec), SCHEMA_CHANGE(5, SchemaChange.subcodec); public final int id; public final Message.Codec<ResultMessage> subcodec; private static final Kind[] ids; static { int maxId = -1; for (Kind k : Kind.values()) maxId = Math.max(maxId, k.id); ids = new Kind[maxId + 1]; for (Kind k : Kind.values()) { if (ids[k.id] != null) throw new IllegalStateException("Duplicate kind id"); ids[k.id] = k; } } private Kind(int id, Message.Codec<ResultMessage> subcodec) { this.id = id; this.subcodec = subcodec; } public static Kind fromId(int id) { Kind k = ids[id]; if (k == null) throw new ProtocolException(String.format("Unknown kind id %d in RESULT message", id)); return k; } } public final Kind kind; protected ResultMessage(Kind kind) { super(Message.Type.RESULT); this.kind = kind; } public static class Void extends ResultMessage { // Even though we have no specific information here, don't make a // singleton since as each message it has in fact a streamid and connection. public Void() { super(Kind.VOID); } public static final Message.Codec<ResultMessage> subcodec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { return new Void(); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { assert msg instanceof Void; } public int encodedSize(ResultMessage msg, ProtocolVersion version) { return 0; } }; @Override public String toString() { return "EMPTY RESULT"; } } public static class SetKeyspace extends ResultMessage { public final String keyspace; public SetKeyspace(String keyspace) { super(Kind.SET_KEYSPACE); this.keyspace = keyspace; } public static final Message.Codec<ResultMessage> subcodec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { String keyspace = CBUtil.readString(body); return new SetKeyspace(keyspace); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { assert msg instanceof SetKeyspace; CBUtil.writeAsciiString(((SetKeyspace) msg).keyspace, dest); } public int encodedSize(ResultMessage msg, ProtocolVersion version) { assert msg instanceof SetKeyspace; return CBUtil.sizeOfAsciiString(((SetKeyspace) msg).keyspace); } }; @Override public String toString() { return "RESULT set keyspace " + keyspace; } } public static class Rows extends ResultMessage { public static final Message.Codec<ResultMessage> subcodec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { return new Rows(ResultSet.codec.decode(body, version)); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { assert msg instanceof Rows; Rows rowMsg = (Rows) msg; ResultSet.codec.encode(rowMsg.result, dest, version); } public int encodedSize(ResultMessage msg, ProtocolVersion version) { assert msg instanceof Rows; Rows rowMsg = (Rows) msg; return ResultSet.codec.encodedSize(rowMsg.result, version); } }; public final ResultSet result; public Rows(ResultSet result) { super(Kind.ROWS); this.result = result; } @Override public String toString() { return "ROWS " + result; } } public static class Prepared extends ResultMessage { public static final Message.Codec<ResultMessage> subcodec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { MD5Digest id = MD5Digest.wrap(CBUtil.readBytes(body)); MD5Digest resultMetadataId = null; if (version.isGreaterOrEqualTo(ProtocolVersion.V5)) resultMetadataId = MD5Digest.wrap(CBUtil.readBytes(body)); ResultSet.PreparedMetadata metadata = ResultSet.PreparedMetadata.codec.decode(body, version); ResultSet.ResultMetadata resultMetadata = ResultSet.ResultMetadata.EMPTY; if (version.isGreaterThan(ProtocolVersion.V1)) resultMetadata = ResultSet.ResultMetadata.codec.decode(body, version); return new Prepared(id, resultMetadataId, metadata, resultMetadata); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { assert msg instanceof Prepared; Prepared prepared = (Prepared) msg; assert prepared.statementId != null; CBUtil.writeBytes(prepared.statementId.bytes, dest); if (version.isGreaterOrEqualTo(ProtocolVersion.V5)) CBUtil.writeBytes(prepared.resultMetadataId.bytes, dest); ResultSet.PreparedMetadata.codec.encode(prepared.metadata, dest, version); if (version.isGreaterThan(ProtocolVersion.V1)) ResultSet.ResultMetadata.codec.encode(prepared.resultMetadata, dest, version); } public int encodedSize(ResultMessage msg, ProtocolVersion version) { assert msg instanceof Prepared; Prepared prepared = (Prepared) msg; assert prepared.statementId != null; int size = 0; size += CBUtil.sizeOfBytes(prepared.statementId.bytes); if (version.isGreaterOrEqualTo(ProtocolVersion.V5)) size += CBUtil.sizeOfBytes(prepared.resultMetadataId.bytes); size += ResultSet.PreparedMetadata.codec.encodedSize(prepared.metadata, version); if (version.isGreaterThan(ProtocolVersion.V1)) size += ResultSet.ResultMetadata.codec.encodedSize(prepared.resultMetadata, version); return size; } }; public final MD5Digest statementId; public final MD5Digest resultMetadataId; /** Describes the variables to be bound in the prepared statement */ public final ResultSet.PreparedMetadata metadata; /** Describes the results of executing this prepared statement */ public final ResultSet.ResultMetadata resultMetadata; public Prepared(MD5Digest statementId, MD5Digest resultMetadataId, ResultSet.PreparedMetadata metadata, ResultSet.ResultMetadata resultMetadata) { super(Kind.PREPARED); this.statementId = statementId; this.resultMetadataId = resultMetadataId; this.metadata = metadata; this.resultMetadata = resultMetadata; } @VisibleForTesting public Prepared withResultMetadata(ResultSet.ResultMetadata resultMetadata) { return new Prepared(statementId, resultMetadata.getResultMetadataId(), metadata, resultMetadata); } @Override public String toString() { return "RESULT PREPARED " + statementId + " " + metadata + " (resultMetadata=" + resultMetadata + ")"; } } public static class SchemaChange extends ResultMessage { public final Event.SchemaChange change; public SchemaChange(Event.SchemaChange change) { super(Kind.SCHEMA_CHANGE); this.change = change; } public static final Message.Codec<ResultMessage> subcodec = new Message.Codec<ResultMessage>() { public ResultMessage decode(ByteBuf body, ProtocolVersion version) { return new SchemaChange(Event.SchemaChange.deserializeEvent(body, version)); } public void encode(ResultMessage msg, ByteBuf dest, ProtocolVersion version) { assert msg instanceof SchemaChange; SchemaChange scm = (SchemaChange) msg; scm.change.serializeEvent(dest, version); } public int encodedSize(ResultMessage msg, ProtocolVersion version) { assert msg instanceof SchemaChange; SchemaChange scm = (SchemaChange) msg; return scm.change.eventSerializedSize(version); } }; @Override public String toString() { return "RESULT schema change " + change; } } }