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The MongoDB Java Driver uber-artifact, containing 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.operation;
import com.mongodb.MongoCommandException;
import com.mongodb.MongoException;
import com.mongodb.MongoNamespace;
import com.mongodb.ReadPreference;
import com.mongodb.ServerAddress;
import com.mongodb.ServerCursor;
import com.mongodb.binding.ConnectionSource;
import com.mongodb.connection.Connection;
import com.mongodb.connection.QueryResult;
import com.mongodb.internal.validator.NoOpFieldNameValidator;
import org.bson.BsonArray;
import org.bson.BsonDocument;
import org.bson.BsonInt32;
import org.bson.BsonInt64;
import org.bson.BsonString;
import org.bson.FieldNameValidator;
import org.bson.codecs.BsonDocumentCodec;
import org.bson.codecs.Decoder;
import java.util.List;
import java.util.NoSuchElementException;
import static com.mongodb.assertions.Assertions.isTrueArgument;
import static com.mongodb.assertions.Assertions.notNull;
import static com.mongodb.operation.CursorHelper.getNumberToReturn;
import static com.mongodb.operation.OperationHelper.getMoreCursorDocumentToQueryResult;
import static com.mongodb.internal.operation.ServerVersionHelper.serverIsAtLeastVersionThreeDotTwo;
import static com.mongodb.operation.QueryHelper.translateCommandException;
import static java.util.Collections.singletonList;
class QueryBatchCursor implements BatchCursor {
private static final FieldNameValidator NO_OP_FIELD_NAME_VALIDATOR = new NoOpFieldNameValidator();
private final MongoNamespace namespace;
private final ServerAddress serverAddress;
private final int limit;
private final Decoder decoder;
private final long maxTimeMS;
private int batchSize;
private ConnectionSource connectionSource;
private ServerCursor serverCursor;
private List nextBatch;
private int count;
private volatile boolean closed;
QueryBatchCursor(final QueryResult firstQueryResult, final int limit, final int batchSize, final Decoder decoder) {
this(firstQueryResult, limit, batchSize, decoder, null);
}
QueryBatchCursor(final QueryResult firstQueryResult, final int limit, final int batchSize,
final Decoder decoder, final ConnectionSource connectionSource) {
this(firstQueryResult, limit, batchSize, 0, decoder, connectionSource, null);
}
QueryBatchCursor(final QueryResult firstQueryResult, final int limit, final int batchSize, final long maxTimeMS,
final Decoder decoder, final ConnectionSource connectionSource, final Connection connection) {
isTrueArgument("maxTimeMS >= 0", maxTimeMS >= 0);
this.maxTimeMS = maxTimeMS;
this.namespace = firstQueryResult.getNamespace();
this.serverAddress = firstQueryResult.getAddress();
this.limit = limit;
this.batchSize = batchSize;
this.decoder = notNull("decoder", decoder);
if (firstQueryResult.getCursor() != null) {
notNull("connectionSource", connectionSource);
}
if (connectionSource != null) {
this.connectionSource = connectionSource.retain();
} else {
this.connectionSource = null;
}
initFromQueryResult(firstQueryResult);
if (limitReached()) {
killCursor(connection);
}
if (serverCursor == null && this.connectionSource != null) {
this.connectionSource.release();
this.connectionSource = null;
}
}
@Override
public boolean hasNext() {
if (closed) {
throw new IllegalStateException("Cursor has been closed");
}
if (nextBatch != null) {
return true;
}
if (limitReached()) {
return false;
}
while (serverCursor != null) {
getMore();
if (closed) {
throw new IllegalStateException("Cursor has been closed");
}
if (nextBatch != null) {
return true;
}
}
return false;
}
@Override
public List next() {
if (closed) {
throw new IllegalStateException("Iterator has been closed");
}
if (!hasNext()) {
throw new NoSuchElementException();
}
List retVal = nextBatch;
nextBatch = null;
return retVal;
}
@Override
public void setBatchSize(final int batchSize) {
this.batchSize = batchSize;
}
@Override
public int getBatchSize() {
return batchSize;
}
@Override
public void remove() {
throw new UnsupportedOperationException("Not implemented yet!");
}
@Override
public void close() {
if (!closed) {
closed = true;
try {
killCursor();
} finally {
if (connectionSource != null) {
connectionSource.release();
}
}
}
}
@Override
public List tryNext() {
if (closed) {
throw new IllegalStateException("Cursor has been closed");
}
if (!tryHasNext()) {
return null;
}
return next();
}
boolean tryHasNext() {
if (nextBatch != null) {
return true;
}
if (limitReached()) {
return false;
}
if (serverCursor != null) {
getMore();
}
return nextBatch != null;
}
@Override
public ServerCursor getServerCursor() {
if (closed) {
throw new IllegalStateException("Iterator has been closed");
}
return serverCursor;
}
@Override
public ServerAddress getServerAddress() {
if (closed) {
throw new IllegalStateException("Iterator has been closed");
}
return serverAddress;
}
private void getMore() {
Connection connection = connectionSource.getConnection();
try {
if (serverIsAtLeastVersionThreeDotTwo(connection.getDescription())) {
try {
initFromCommandResult(connection.command(namespace.getDatabaseName(),
asGetMoreCommandDocument(),
NO_OP_FIELD_NAME_VALIDATOR,
ReadPreference.primary(),
CommandResultDocumentCodec.create(decoder, "nextBatch"),
connectionSource.getSessionContext()));
} catch (MongoCommandException e) {
throw translateCommandException(e, serverCursor);
}
} else {
QueryResult getMore = connection.getMore(namespace, serverCursor.getId(),
getNumberToReturn(limit, batchSize, count), decoder);
initFromQueryResult(getMore);
}
if (limitReached()) {
killCursor(connection);
}
if (serverCursor == null) {
this.connectionSource.release();
this.connectionSource = null;
}
} finally {
connection.release();
}
}
private BsonDocument asGetMoreCommandDocument() {
BsonDocument document = new BsonDocument("getMore", new BsonInt64(serverCursor.getId()))
.append("collection", new BsonString(namespace.getCollectionName()));
int batchSizeForGetMoreCommand = Math.abs(getNumberToReturn(limit, this.batchSize, count));
if (batchSizeForGetMoreCommand != 0) {
document.append("batchSize", new BsonInt32(batchSizeForGetMoreCommand));
}
if (maxTimeMS != 0) {
document.append("maxTimeMS", new BsonInt64(maxTimeMS));
}
return document;
}
private void initFromQueryResult(final QueryResult queryResult) {
serverCursor = queryResult.getCursor();
nextBatch = queryResult.getResults().isEmpty() ? null : queryResult.getResults();
count += queryResult.getResults().size();
}
private void initFromCommandResult(final BsonDocument getMoreCommandResultDocument) {
QueryResult queryResult = getMoreCursorDocumentToQueryResult(getMoreCommandResultDocument.getDocument("cursor"),
connectionSource.getServerDescription().getAddress());
initFromQueryResult(queryResult);
}
private boolean limitReached() {
return Math.abs(limit) != 0 && count >= Math.abs(limit);
}
private void killCursor() {
if (serverCursor != null) {
try {
Connection connection = connectionSource.getConnection();
try {
killCursor(connection);
} finally {
connection.release();
}
} catch (MongoException e) {
// Ignore exceptions from calling killCursor
}
}
}
private void killCursor(final Connection connection) {
if (serverCursor != null) {
notNull("connection", connection);
if (serverIsAtLeastVersionThreeDotTwo(connection.getDescription())) {
connection.command(namespace.getDatabaseName(), asKillCursorsCommandDocument(), NO_OP_FIELD_NAME_VALIDATOR,
ReadPreference.primary(), new BsonDocumentCodec(), connectionSource.getSessionContext());
} else {
connection.killCursor(namespace, singletonList(serverCursor.getId()));
}
serverCursor = null;
}
}
private BsonDocument asKillCursorsCommandDocument() {
return new BsonDocument("killCursors", new BsonString(namespace.getCollectionName()))
.append("cursors", new BsonArray(singletonList(new BsonInt64(serverCursor.getId()))));
}
}
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