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The MongoDB Java Driver uber-artifact, containing the legacy driver, the mongodb-driver, mongodb-driver-core, and bson
/*
* Copyright 2008-present MongoDB, 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 com.mongodb.internal.connection;
import com.mongodb.MongoNamespace;
import com.mongodb.ReadPreference;
import com.mongodb.connection.ByteBufferBsonOutput;
import com.mongodb.connection.ClusterConnectionMode;
import com.mongodb.connection.ServerVersion;
import com.mongodb.connection.SplittablePayload;
import com.mongodb.internal.validator.MappedFieldNameValidator;
import com.mongodb.session.SessionContext;
import org.bson.BsonArray;
import org.bson.BsonBinaryWriter;
import org.bson.BsonBoolean;
import org.bson.BsonDocument;
import org.bson.BsonElement;
import org.bson.BsonInt64;
import org.bson.BsonString;
import org.bson.BsonWriter;
import org.bson.FieldNameValidator;
import org.bson.codecs.EncoderContext;
import org.bson.io.BsonOutput;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import static com.mongodb.ReadPreference.primary;
import static com.mongodb.ReadPreference.primaryPreferred;
import static com.mongodb.assertions.Assertions.isTrue;
import static com.mongodb.connection.ClusterConnectionMode.MULTIPLE;
import static com.mongodb.connection.ClusterConnectionMode.SINGLE;
import static com.mongodb.connection.ServerType.SHARD_ROUTER;
import static com.mongodb.internal.connection.BsonWriterHelper.writePayload;
import static com.mongodb.internal.connection.ReadConcernHelper.getReadConcernDocument;
/**
* A command message that uses OP_MSG or OP_QUERY to send the command.
*/
public final class CommandMessage extends RequestMessage {
private final MongoNamespace namespace;
private final BsonDocument command;
private final FieldNameValidator commandFieldNameValidator;
private final ReadPreference readPreference;
private final SplittablePayload payload;
private final FieldNameValidator payloadFieldNameValidator;
private final boolean responseExpected;
private final ClusterConnectionMode clusterConnectionMode;
CommandMessage(final MongoNamespace namespace, final BsonDocument command, final FieldNameValidator commandFieldNameValidator,
final ReadPreference readPreference, final MessageSettings settings) {
this(namespace, command, commandFieldNameValidator, readPreference, settings, true, null, null,
MULTIPLE);
}
CommandMessage(final MongoNamespace namespace, final BsonDocument command, final FieldNameValidator commandFieldNameValidator,
final ReadPreference readPreference, final MessageSettings settings, final boolean responseExpected,
final SplittablePayload payload, final FieldNameValidator payloadFieldNameValidator,
final ClusterConnectionMode clusterConnectionMode) {
super(namespace.getFullName(), getOpCode(settings), settings);
this.namespace = namespace;
this.command = command;
this.commandFieldNameValidator = commandFieldNameValidator;
this.readPreference = readPreference;
this.responseExpected = responseExpected;
this.payload = payload;
this.payloadFieldNameValidator = payloadFieldNameValidator;
this.clusterConnectionMode = clusterConnectionMode;
}
BsonDocument getCommandDocument(final ByteBufferBsonOutput bsonOutput) {
ByteBufBsonDocument byteBufBsonDocument = ByteBufBsonDocument.createOne(bsonOutput,
getEncodingMetadata().getFirstDocumentPosition());
BsonDocument commandBsonDocument;
if (useOpMsg() && containsPayload()) {
commandBsonDocument = byteBufBsonDocument.toBsonDocument();
int payloadStartPosition = getEncodingMetadata().getFirstDocumentPosition()
+ byteBufBsonDocument.getSizeInBytes()
+ 1 // payload type
+ 4 // payload size
+ payload.getPayloadName().getBytes(Charset.forName("UTF-8")).length + 1; // null-terminated UTF-8 payload name
commandBsonDocument.append(payload.getPayloadName(),
new BsonArray(ByteBufBsonDocument.createList(bsonOutput, payloadStartPosition)));
} else {
commandBsonDocument = byteBufBsonDocument;
}
if (commandBsonDocument.containsKey("$query")) {
commandBsonDocument = commandBsonDocument.getDocument("$query");
}
return commandBsonDocument;
}
boolean containsPayload() {
return payload != null;
}
boolean isResponseExpected() {
isTrue("The message must be encoded before determining if a response is expected", getEncodingMetadata() != null);
return !useOpMsg() || requireOpMsgResponse();
}
MongoNamespace getNamespace() {
return namespace;
}
@Override
protected EncodingMetadata encodeMessageBodyWithMetadata(final BsonOutput bsonOutput, final SessionContext sessionContext) {
int messageStartPosition = bsonOutput.getPosition() - MESSAGE_PROLOGUE_LENGTH;
int commandStartPosition;
if (useOpMsg()) {
int flagPosition = bsonOutput.getPosition();
bsonOutput.writeInt32(0); // flag bits
bsonOutput.writeByte(0); // payload type
commandStartPosition = bsonOutput.getPosition();
addDocument(getCommandToEncode(), bsonOutput, commandFieldNameValidator, getExtraElements(sessionContext));
if (payload != null) {
bsonOutput.writeByte(1); // payload type
int payloadBsonOutputStartPosition = bsonOutput.getPosition();
bsonOutput.writeInt32(0); // size
bsonOutput.writeCString(payload.getPayloadName());
writePayload(new BsonBinaryWriter(bsonOutput, payloadFieldNameValidator), bsonOutput, getSettings(),
messageStartPosition, payload);
int payloadBsonOutputLength = bsonOutput.getPosition() - payloadBsonOutputStartPosition;
bsonOutput.writeInt32(payloadBsonOutputStartPosition, payloadBsonOutputLength);
}
// Write the flag bits
bsonOutput.writeInt32(flagPosition, getOpMsgFlagBits());
} else {
bsonOutput.writeInt32(getOpQueryFlagBits());
bsonOutput.writeCString(namespace.getFullName());
bsonOutput.writeInt32(0);
bsonOutput.writeInt32(-1);
commandStartPosition = bsonOutput.getPosition();
if (payload == null) {
addDocument(getCommandToEncode(), bsonOutput, commandFieldNameValidator, null);
} else {
addDocumentWithPayload(bsonOutput, messageStartPosition);
}
}
return new EncodingMetadata(commandStartPosition);
}
private FieldNameValidator getPayloadArrayFieldNameValidator() {
Map rootMap = new HashMap();
rootMap.put(payload.getPayloadName(), payloadFieldNameValidator);
return new MappedFieldNameValidator(commandFieldNameValidator, rootMap);
}
private void addDocumentWithPayload(final BsonOutput bsonOutput, final int messageStartPosition) {
BsonBinaryWriter bsonBinaryWriter = new BsonBinaryWriter(bsonOutput, getPayloadArrayFieldNameValidator());
BsonWriter bsonWriter = new SplittablePayloadBsonWriter(bsonBinaryWriter, bsonOutput, messageStartPosition, getSettings(), payload);
BsonDocument commandToEncode = getCommandToEncode();
getCodec(commandToEncode).encode(bsonWriter, commandToEncode, EncoderContext.builder().build());
}
private int getOpMsgFlagBits() {
return getOpMsgResponseExpectedFlagBit();
}
private int getOpMsgResponseExpectedFlagBit() {
if (requireOpMsgResponse()) {
return 0;
} else {
return 1 << 1;
}
}
private boolean requireOpMsgResponse() {
if (responseExpected) {
return true;
} else {
return payload != null && payload.hasAnotherSplit();
}
}
private int getOpQueryFlagBits() {
return getOpQuerySlaveOkFlagBit();
}
private int getOpQuerySlaveOkFlagBit() {
if (isSlaveOk()) {
return 1 << 2;
} else {
return 0;
}
}
private boolean isSlaveOk() {
return (readPreference != null && readPreference.isSlaveOk()) || isDirectConnectionToNonShardRouter();
}
private boolean isDirectConnectionToNonShardRouter() {
return clusterConnectionMode == SINGLE && getSettings().getServerType() != SHARD_ROUTER;
}
private boolean useOpMsg() {
return getOpCode().equals(OpCode.OP_MSG);
}
private BsonDocument getCommandToEncode() {
BsonDocument commandToEncode = command;
if (!useOpMsg() && readPreference != null && !readPreference.equals(primary())) {
commandToEncode = new BsonDocument("$query", command).append("$readPreference", readPreference.toDocument());
}
return commandToEncode;
}
private List getExtraElements(final SessionContext sessionContext) {
List extraElements = new ArrayList();
extraElements.add(new BsonElement("$db", new BsonString(new MongoNamespace(getCollectionName()).getDatabaseName())));
if (sessionContext.getClusterTime() != null) {
extraElements.add(new BsonElement("$clusterTime", sessionContext.getClusterTime()));
}
if (sessionContext.hasSession() && responseExpected) {
extraElements.add(new BsonElement("lsid", sessionContext.getSessionId()));
}
boolean firstMessageInTransaction = sessionContext.notifyMessageSent();
if (sessionContext.hasActiveTransaction()) {
extraElements.add(new BsonElement("txnNumber", new BsonInt64(sessionContext.getTransactionNumber())));
if (firstMessageInTransaction) {
extraElements.add(new BsonElement("startTransaction", BsonBoolean.TRUE));
addReadConcernDocument(extraElements, sessionContext);
}
extraElements.add(new BsonElement("autocommit", BsonBoolean.FALSE));
}
if (readPreference != null) {
if (!readPreference.equals(primary())) {
extraElements.add(new BsonElement("$readPreference", readPreference.toDocument()));
} else if (isDirectConnectionToNonShardRouter()) {
extraElements.add(new BsonElement("$readPreference", primaryPreferred().toDocument()));
}
}
return extraElements;
}
private void addReadConcernDocument(final List extraElements, final SessionContext sessionContext) {
BsonDocument readConcernDocument = getReadConcernDocument(sessionContext);
if (!readConcernDocument.isEmpty()) {
extraElements.add(new BsonElement("readConcern", readConcernDocument));
}
}
private static OpCode getOpCode(final MessageSettings settings) {
return isServerVersionAtLeastThreeDotSix(settings) ? OpCode.OP_MSG : OpCode.OP_QUERY;
}
private static boolean isServerVersionAtLeastThreeDotSix(final MessageSettings settings) {
return settings.getServerVersion().compareTo(new ServerVersion(3, 6)) >= 0;
}
}