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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.session.SessionContext;
import org.bson.BsonBinaryWriter;
import org.bson.BsonBinaryWriterSettings;
import org.bson.BsonDocument;
import org.bson.BsonElement;
import org.bson.BsonWriter;
import org.bson.BsonWriterSettings;
import org.bson.FieldNameValidator;
import org.bson.codecs.BsonValueCodecProvider;
import org.bson.codecs.Codec;
import org.bson.codecs.Encoder;
import org.bson.codecs.EncoderContext;
import org.bson.codecs.configuration.CodecRegistry;
import org.bson.io.BsonOutput;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import static com.mongodb.assertions.Assertions.notNull;
import static org.bson.codecs.configuration.CodecRegistries.fromProviders;
/**
* Abstract base class for all MongoDB Wire Protocol request messages.
*/
abstract class RequestMessage {
static final AtomicInteger REQUEST_ID = new AtomicInteger(1);
static final int MESSAGE_PROLOGUE_LENGTH = 16;
// Allow an extra 16K to the maximum allowed size of a query or command document, so that, for example,
// a 16M document can be upserted via findAndModify
private static final int DOCUMENT_HEADROOM = 16 * 1024;
private static final CodecRegistry REGISTRY = fromProviders(new BsonValueCodecProvider());
private final String collectionName;
private final MessageSettings settings;
private final int id;
private final OpCode opCode;
private EncodingMetadata encodingMetadata;
static class EncodingMetadata {
private final int firstDocumentPosition;
EncodingMetadata(final int firstDocumentPosition) {
this.firstDocumentPosition = firstDocumentPosition;
}
public int getFirstDocumentPosition() {
return firstDocumentPosition;
}
}
/**
* Gets the next available unique message identifier.
*
* @return the message identifier
*/
public static int getCurrentGlobalId() {
return REQUEST_ID.get();
}
RequestMessage(final OpCode opCode, final MessageSettings settings) {
this(null, opCode, settings);
}
RequestMessage(final OpCode opCode, final int requestId, final MessageSettings settings) {
this(null, opCode, requestId, settings);
}
RequestMessage(final String collectionName, final OpCode opCode, final MessageSettings settings) {
this(collectionName, opCode, REQUEST_ID.getAndIncrement(), settings);
}
private RequestMessage(final String collectionName, final OpCode opCode, final int requestId, final MessageSettings settings) {
this.collectionName = collectionName;
this.settings = settings;
id = requestId;
this.opCode = opCode;
}
/**
* Gets the message id.
*
* @return the message id
*/
public int getId() {
return id;
}
/**
* Gets the op code of the message.
*
* @return the op code
*/
public OpCode getOpCode() {
return opCode;
}
/**
* Gets the message settings.
*
* @return the message settings
*/
public MessageSettings getSettings() {
return settings;
}
/**
* Encoded the message to the given output.
*
* @param bsonOutput the output
* @param sessionContext the session context
*/
public void encode(final BsonOutput bsonOutput, final SessionContext sessionContext) {
notNull("sessionContext", sessionContext);
int messageStartPosition = bsonOutput.getPosition();
writeMessagePrologue(bsonOutput);
EncodingMetadata encodingMetadata = encodeMessageBodyWithMetadata(bsonOutput, sessionContext);
backpatchMessageLength(messageStartPosition, bsonOutput);
this.encodingMetadata = encodingMetadata;
}
/**
* Gets the encoding metadata from the last attempt to encode this message.
*
* @return Get metadata from the last attempt to encode this message. Returns null if there has not yet been an attempt.
*/
public EncodingMetadata getEncodingMetadata() {
return encodingMetadata;
}
/**
* Writes the message prologue to the given output.
*
* @param bsonOutput the output
*/
protected void writeMessagePrologue(final BsonOutput bsonOutput) {
bsonOutput.writeInt32(0); // length: will set this later
bsonOutput.writeInt32(id);
bsonOutput.writeInt32(0); // response to
bsonOutput.writeInt32(opCode.getValue());
}
/**
* Encode the message body to the given output.
*
* @param bsonOutput the output
* @param sessionContext the session context
* @return the encoding metadata
*/
protected abstract EncodingMetadata encodeMessageBodyWithMetadata(BsonOutput bsonOutput, SessionContext sessionContext);
/**
* Appends a document to the message.
*
* @param document the document
* @param bsonOutput the output
* @param validator the field name validator
*/
protected void addDocument(final BsonDocument document, final BsonOutput bsonOutput,
final FieldNameValidator validator) {
addDocument(document, getCodec(document), EncoderContext.builder().build(), bsonOutput, validator,
settings.getMaxDocumentSize() + DOCUMENT_HEADROOM, null);
}
protected void addDocument(final BsonDocument document, final BsonOutput bsonOutput,
final FieldNameValidator validator, final List extraElements) {
addDocument(document, getCodec(document), EncoderContext.builder().build(), bsonOutput, validator,
settings.getMaxDocumentSize() + DOCUMENT_HEADROOM, extraElements);
}
/**
* Appends a document to the message that is intended for storage in a collection.
*
* @param document the document
* @param bsonOutput the output
* @param validator the field name validator
*/
protected void addCollectibleDocument(final BsonDocument document, final BsonOutput bsonOutput, final FieldNameValidator validator) {
addDocument(document, getCodec(document), EncoderContext.builder().isEncodingCollectibleDocument(true).build(), bsonOutput,
validator, settings.getMaxDocumentSize(), null);
}
/**
* Backpatches the message length into the beginning of the message.
*
* @param startPosition the start position of the message
* @param bsonOutput the output
*/
protected void backpatchMessageLength(final int startPosition, final BsonOutput bsonOutput) {
int messageLength = bsonOutput.getPosition() - startPosition;
bsonOutput.writeInt32(bsonOutput.getPosition() - messageLength, messageLength);
}
/**
* Gets the collection name, which may be null for some message types
*
* @return the collection name
*/
protected String getCollectionName() {
return collectionName;
}
@SuppressWarnings("unchecked")
Codec getCodec(final BsonDocument document) {
return (Codec) REGISTRY.get(document.getClass());
}
@SuppressWarnings("unchecked")
private void addDocument(final T obj, final Encoder encoder, final EncoderContext encoderContext,
final BsonOutput bsonOutput, final FieldNameValidator validator, final int maxDocumentSize,
final List extraElements) {
BsonBinaryWriter bsonBinaryWriter = new BsonBinaryWriter(new BsonWriterSettings(), new BsonBinaryWriterSettings(maxDocumentSize),
bsonOutput, validator);
BsonWriter bsonWriter = extraElements == null
? bsonBinaryWriter
: new ElementExtendingBsonWriter(bsonBinaryWriter, extraElements);
encoder.encode(bsonWriter, obj, encoderContext);
}
}