/*
* Copyright (c) 2008-2014 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.connection;
import com.mongodb.MongoInternalException;
import org.bson.io.BsonInput;
import static java.lang.String.format;
/**
* Contains the details of a reply from a MongoDB server.
*
* @mongodb.driver.manual ../meta-driver/latest/legacy/mongodb-wire-protocol/#database-response-messages Database Response Messages
*/
class ReplyHeader {
/**
* The length of the reply header in the MongoDB wire protocol.
*/
public static final int REPLY_HEADER_LENGTH = 36;
private static final int CURSOR_NOT_FOUND_RESPONSE_FLAG = 1;
private static final int QUERY_FAILURE_RESPONSE_FLAG = 2;
private static final int OP_REPLY_OP_CODE = 1;
private static final int MIN_BSON_DOCUMENT_LENGTH = 5;
private final int messageLength;
private final int requestId;
private final int responseTo;
private final int responseFlags;
private final long cursorId;
private final int startingFrom;
private final int numberReturned;
ReplyHeader(final BsonInput header, final int maxMessageLength) {
messageLength = header.readInt32();
requestId = header.readInt32();
responseTo = header.readInt32();
int opCode = header.readInt32();
responseFlags = header.readInt32();
cursorId = header.readInt64();
startingFrom = header.readInt32();
numberReturned = header.readInt32();
if (opCode != OP_REPLY_OP_CODE) {
throw new MongoInternalException(format("The reply message opCode %d does not match the expected opCode %d",
opCode, OP_REPLY_OP_CODE));
}
if (messageLength < REPLY_HEADER_LENGTH) {
throw new MongoInternalException(format("The reply message length %d is less than the mimimum message length %d", messageLength,
REPLY_HEADER_LENGTH));
}
if (messageLength > maxMessageLength) {
throw new MongoInternalException(String.format("The reply message length %d is less than the maximum message length %d",
messageLength, maxMessageLength));
}
if (numberReturned < 0) {
throw new MongoInternalException(format("The reply message number of returned documents, %d, is less than 0", numberReturned));
}
}
/**
* Gets the total size of the message in bytes. This total includes the 4 bytes that holds the message length.
*
* @return the total message size, including all of the header
*/
public int getMessageLength() {
return messageLength;
}
/**
* This is a client or database-generated identifier that uniquely identifies this message. Along with the {@code responseTo} field in
* responses, clients can use this to associate query responses with the originating query.
*
* @return the identifier for this message
*/
public int getRequestId() {
return requestId;
}
/**
* Along with the requestID field in queries, clients can use this to associate query responses with the originating query.
*
* @return the request ID from the original request
*/
public int getResponseTo() {
return responseTo;
}
/**
* Gets additional information about the response.
* <ul>
* <li>0 - <i>CursorNotFound</i>: Set when getMore is called but the cursor id is not valid at the server. Returned with zero
* results.</li>
* <li>1 - <i>QueryFailure</i>: Set when query failed. Results consist of one document containing an "$err" field describing the
* failure.
* <li>2 - <i>ShardConfigStale</i>: Drivers should ignore this. Only mongos will ever see this set, in which case,
* it needs to update config from the server.
* <li>3 - <i>AwaitCapable</i>: Set when the server supports the AwaitData Query option. If it doesn't,
* a client should sleep a little between getMore's of a Tailable cursor. Mongod version 1.6 supports AwaitData and thus always
* sets AwaitCapable.
* <li>4-31 - <i>Reserved</i>: Ignore
* </ul>
*
* @return bit vector - see details above
*/
public int getResponseFlags() {
return responseFlags;
}
/**
* Gets the cursor ID that this response is a part of. If there are no more documents to fetch from the server, the cursor ID will be 0.
* This cursor ID must be used in any messages used to get more data, and also must be closed by the client when no longer needed.
*
* @return cursor ID to use if the client needs to fetch more from the server
*/
public long getCursorId() {
return cursorId;
}
/**
* Returns the position in the cursor that is the start point of this reply.
*
* @return where in the cursor this reply is starting
*/
public int getStartingFrom() {
return startingFrom;
}
/**
* Gets the number of documents to expect in the body of this reply.
*
* @return number of documents in the reply
*/
public int getNumberReturned() {
return numberReturned;
}
/**
* Gets whether this query was performed with a cursor ID that was not valid on the server.
*
* @return true if this reply indicates the request to get more data was performed with a cursor ID that's not valid on the server
*/
public boolean isCursorNotFound() {
return (responseFlags & CURSOR_NOT_FOUND_RESPONSE_FLAG) == CURSOR_NOT_FOUND_RESPONSE_FLAG;
}
/**
* Gets whether the query failed or not.
*
* @return true if this reply indicates the query failed.
*/
public boolean isQueryFailure() {
return (responseFlags & QUERY_FAILURE_RESPONSE_FLAG) == QUERY_FAILURE_RESPONSE_FLAG;
}
}