/*
* 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.operation;
import com.mongodb.ServerAddress;
import com.mongodb.async.AsyncBatchCursor;
import com.mongodb.async.SingleResultCallback;
import com.mongodb.binding.AsyncConnectionSource;
import com.mongodb.binding.AsyncReadBinding;
import com.mongodb.binding.ConnectionSource;
import com.mongodb.binding.ReadBinding;
import com.mongodb.connection.AsyncConnection;
import com.mongodb.connection.Connection;
import com.mongodb.connection.ConnectionDescription;
import com.mongodb.connection.QueryResult;
import com.mongodb.operation.CommandOperationHelper.CommandTransformer;
import org.bson.BsonDocument;
import org.bson.BsonInt32;
import org.bson.BsonInt64;
import org.bson.codecs.Decoder;
import java.util.concurrent.TimeUnit;
import static com.mongodb.assertions.Assertions.notNull;
import static com.mongodb.internal.async.ErrorHandlingResultCallback.errorHandlingCallback;
import static com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocol;
import static com.mongodb.operation.CommandOperationHelper.executeWrappedCommandProtocolAsync;
import static com.mongodb.operation.OperationHelper.AsyncCallableWithConnectionAndSource;
import static com.mongodb.operation.OperationHelper.LOGGER;
import static com.mongodb.operation.OperationHelper.releasingCallback;
import static com.mongodb.operation.OperationHelper.withConnection;
/**
* An operation that provides a cursor allowing iteration through the metadata of all the databases for a MongoClient.
*
* @param <T> the document type
* @since 3.0
*/
public class ListDatabasesOperation<T> implements AsyncReadOperation<AsyncBatchCursor<T>>, ReadOperation<BatchCursor<T>> {
private final Decoder<T> decoder;
private long maxTimeMS;
/**
* Construct a new instance.
*
* @param decoder the decoder to use for the results
*/
public ListDatabasesOperation(final Decoder<T> decoder) {
this.decoder = notNull("decoder", decoder);
}
/**
* Gets the maximum execution time on the server for this operation. The default is 0, which places no limit on the execution time.
*
* @param timeUnit the time unit to return the result in
* @return the maximum execution time in the given time unit
* @mongodb.driver.manual reference/operator/meta/maxTimeMS/ Max Time
*/
public long getMaxTime(final TimeUnit timeUnit) {
notNull("timeUnit", timeUnit);
return timeUnit.convert(maxTimeMS, TimeUnit.MILLISECONDS);
}
/**
* Sets the maximum execution time on the server for this operation.
*
* @param maxTime the max time
* @param timeUnit the time unit, which may not be null
* @return this
* @mongodb.driver.manual reference/operator/meta/maxTimeMS/ Max Time
*/
public ListDatabasesOperation<T> maxTime(final long maxTime, final TimeUnit timeUnit) {
notNull("timeUnit", timeUnit);
this.maxTimeMS = TimeUnit.MILLISECONDS.convert(maxTime, timeUnit);
return this;
}
/**
* Executing this will return a list of all the databases names in the MongoDB instance.
*
* @param binding the binding.
* @return a List of Strings of the names of all the databases in the MongoDB instance.
*/
@Override
public BatchCursor<T> execute(final ReadBinding binding) {
return withConnection(binding, new OperationHelper.CallableWithConnectionAndSource<BatchCursor<T>>() {
@Override
public BatchCursor<T> call(final ConnectionSource source, final Connection connection) {
return executeWrappedCommandProtocol(binding, "admin", getCommand(),
CommandResultDocumentCodec.create(decoder, "databases"), connection, transformer(source, connection));
}
});
}
@Override
public void executeAsync(final AsyncReadBinding binding, final SingleResultCallback<AsyncBatchCursor<T>> callback) {
withConnection(binding, new AsyncCallableWithConnectionAndSource() {
@Override
public void call(final AsyncConnectionSource source, final AsyncConnection connection, final Throwable t) {
SingleResultCallback<AsyncBatchCursor<T>> errHandlingCallback = errorHandlingCallback(callback, LOGGER);
if (t != null) {
errHandlingCallback.onResult(null, t);
} else {
executeWrappedCommandProtocolAsync(binding, "admin", getCommand(),
CommandResultDocumentCodec.create(decoder, "databases"), connection, asyncTransformer(source, connection),
releasingCallback(errHandlingCallback, connection));
}
}
});
}
private CommandTransformer<BsonDocument, BatchCursor<T>> transformer(final ConnectionSource source, final Connection connection) {
return new CommandTransformer<BsonDocument, BatchCursor<T>>() {
@Override
public BatchCursor<T> apply(final BsonDocument result, final ServerAddress serverAddress) {
return new QueryBatchCursor<T>(createQueryResult(result, connection.getDescription()), 0, 0, decoder, source);
}
};
}
private CommandTransformer<BsonDocument, AsyncBatchCursor<T>> asyncTransformer(final AsyncConnectionSource source,
final AsyncConnection connection) {
return new CommandTransformer<BsonDocument, AsyncBatchCursor<T>>() {
@Override
public AsyncBatchCursor<T> apply(final BsonDocument result, final ServerAddress serverAddress) {
return new AsyncQueryBatchCursor<T>(createQueryResult(result, connection.getDescription()), 0, 0, 0, decoder, source,
connection);
}
};
}
@SuppressWarnings("unchecked")
private QueryResult<T> createQueryResult(final BsonDocument result, final ConnectionDescription description) {
return new QueryResult<T>(null, BsonDocumentWrapperHelper.<T>toList(result, "databases"), 0,
description.getServerAddress());
}
private BsonDocument getCommand() {
BsonDocument command = new BsonDocument("listDatabases", new BsonInt32(1));
if (maxTimeMS > 0) {
command.put("maxTimeMS", new BsonInt64(maxTimeMS));
}
return command;
}
}