/*
* 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.binding;
import com.mongodb.MongoInternalException;
import com.mongodb.MongoTimeoutException;
import com.mongodb.ReadPreference;
import com.mongodb.async.SingleResultCallback;
import com.mongodb.connection.AsyncConnection;
import com.mongodb.connection.Cluster;
import com.mongodb.connection.Server;
import com.mongodb.connection.ServerDescription;
import com.mongodb.selector.ReadPreferenceServerSelector;
import com.mongodb.selector.WritableServerSelector;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import static com.mongodb.ReadPreference.primary;
import static com.mongodb.assertions.Assertions.isTrue;
import static com.mongodb.assertions.Assertions.notNull;
/**
* An asynchronous binding that ensures that all reads use the same connection, and all writes use the same connection.
*
* <p>If the readPreference is {#link ReadPreference.primary()} then all reads and writes will use the same connection.</p>
*/
public class AsyncSingleConnectionBinding extends AbstractReferenceCounted implements AsyncReadWriteBinding {
private final ReadPreference readPreference;
private AsyncConnection readConnection;
private AsyncConnection writeConnection;
private volatile Server readServer;
private volatile Server writeServer;
/**
* Create a new binding with the given cluster.
*
* @param cluster a non-null Cluster which will be used to select a server to bind to
* @param maxWaitTime the maximum time to wait for a connection to become available.
* @param timeUnit a non-null TimeUnit for the maxWaitTime
*/
public AsyncSingleConnectionBinding(final Cluster cluster, final long maxWaitTime, final TimeUnit timeUnit) {
this(cluster, primary(), maxWaitTime, timeUnit);
}
/**
* Create a new binding with the given cluster.
*
* @param cluster a non-null Cluster which will be used to select a server to bind to
* @param readPreference the readPreference for reads, if not primary a separate connection will be used for reads
* @param maxWaitTime the maximum time to wait for a connection to become available.
* @param timeUnit a non-null TimeUnit for the maxWaitTime
*/
public AsyncSingleConnectionBinding(final Cluster cluster, final ReadPreference readPreference,
final long maxWaitTime, final TimeUnit timeUnit) {
notNull("cluster", cluster);
this.readPreference = notNull("readPreference", readPreference);
final CountDownLatch latch = new CountDownLatch(2);
cluster.selectServerAsync(new WritableServerSelector(), new SingleResultCallback<Server>() {
@Override
public void onResult(final Server result, final Throwable t) {
if (t == null) {
writeServer = result;
latch.countDown();
}
}
});
cluster.selectServerAsync(new ReadPreferenceServerSelector(readPreference), new SingleResultCallback<Server>() {
@Override
public void onResult(final Server result, final Throwable t) {
if (t == null) {
readServer = result;
latch.countDown();
}
}
});
awaitLatch(maxWaitTime, timeUnit, latch);
if (writeServer == null || readServer == null) {
throw new MongoInternalException("Failure to select server");
}
final CountDownLatch writeServerLatch = new CountDownLatch(1);
writeServer.getConnectionAsync(new SingleResultCallback<AsyncConnection>() {
@Override
public void onResult(final AsyncConnection result, final Throwable t) {
writeConnection = result;
writeServerLatch.countDown();
}
});
awaitLatch(maxWaitTime, timeUnit, writeServerLatch);
if (writeConnection == null) {
throw new MongoInternalException("Failure to get connection");
}
final CountDownLatch readServerLatch = new CountDownLatch(1);
readServer.getConnectionAsync(new SingleResultCallback<AsyncConnection>() {
@Override
public void onResult(final AsyncConnection result, final Throwable t) {
readConnection = result;
readServerLatch.countDown();
}
});
awaitLatch(maxWaitTime, timeUnit, readServerLatch);
if (readConnection == null) {
throw new MongoInternalException("Failure to get connection");
}
}
private void awaitLatch(final long maxWaitTime, final TimeUnit timeUnit, final CountDownLatch latch) {
try {
if (!latch.await(maxWaitTime, timeUnit)) {
throw new MongoTimeoutException("Failed to get servers");
}
} catch (InterruptedException e) {
throw new MongoInternalException(e.getMessage(), e);
}
}
@Override
public AsyncReadWriteBinding retain() {
super.retain();
return this;
}
@Override
public ReadPreference getReadPreference() {
return readPreference;
}
@Override
public void getReadConnectionSource(final SingleResultCallback<AsyncConnectionSource> callback) {
isTrue("open", getCount() > 0);
if (readPreference == primary()) {
getWriteConnectionSource(callback);
} else {
callback.onResult(new SingleAsyncConnectionSource(readServer, readConnection), null);
}
}
@Override
public void getWriteConnectionSource(final SingleResultCallback<AsyncConnectionSource> callback) {
isTrue("open", getCount() > 0);
callback.onResult(new SingleAsyncConnectionSource(writeServer, writeConnection), null);
}
@Override
public void release() {
super.release();
if (getCount() == 0) {
readConnection.release();
writeConnection.release();
}
}
private final class SingleAsyncConnectionSource extends AbstractReferenceCounted implements AsyncConnectionSource {
private final Server server;
private final AsyncConnection connection;
private SingleAsyncConnectionSource(final Server server, final AsyncConnection connection) {
this.server = server;
this.connection = connection;
AsyncSingleConnectionBinding.this.retain();
}
@Override
public ServerDescription getServerDescription() {
return server.getDescription();
}
@Override
public void getConnection(final SingleResultCallback<AsyncConnection> callback) {
isTrue("open", super.getCount() > 0);
callback.onResult(connection.retain(), null);
}
public AsyncConnectionSource retain() {
super.retain();
return this;
}
@Override
public void release() {
super.release();
if (super.getCount() == 0) {
AsyncSingleConnectionBinding.this.release();
}
}
}
}