/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.facebook.infrastructure.service;
import com.facebook.infrastructure.db.RowMutation;
import com.facebook.infrastructure.net.EndPoint;
import com.facebook.infrastructure.net.Message;
import com.facebook.infrastructure.net.MessagingService;
import com.facebook.infrastructure.utils.*;
import org.apache.log4j.Logger;
import java.io.IOException;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/*
* This class manages the read repairs . This is a singleton class
* it basically uses the cache table construct to schedule writes that have to be
* made for read repairs.
* A cachetable is created which wakes up every n milliseconds specified by
* expirationTimeInMillis and calls a global hook fn on pending entries
* This fn basically sends the message to the appropriate servers to update them
* with the latest changes.
* Author : Avinash Lakshman ( alakshman@facebook.com) & Prashant Malik ( pmalik@facebook.com )
*/
class ReadRepairManager
{
private static Logger logger_ = Logger.getLogger(ReadRepairManager.class);
private static final long expirationTimeInMillis = 2000;
private static Lock lock_ = new ReentrantLock();
private static ReadRepairManager self_ = null;
/*
* This is the internal class which actually
* implements the global hook fn called by the readrepair manager
*/
static class ReadRepairPerformer implements
ICacheExpungeHook<String, Message>
{
private static Logger logger_ = Logger.getLogger(ReadRepairPerformer.class);
/*
* The hook fn which takes the end point and the row mutation that
* needs to be sent to the end point in order
* to perform read repair.
*/
public void callMe(String target,
Message message)
{
String[] pieces = FBUtilities.strip(target, ":");
EndPoint to = new EndPoint(pieces[0], Integer.parseInt(pieces[1]));
MessagingService.getMessagingInstance().sendOneWay(message, to);
}
}
private ICachetable<String, Message> readRepairTable_ = new Cachetable<String, Message>(expirationTimeInMillis, new ReadRepairManager.ReadRepairPerformer());
protected ReadRepairManager()
{
}
public static ReadRepairManager instance()
{
if (self_ == null)
{
lock_.lock();
try
{
if ( self_ == null )
self_ = new ReadRepairManager();
}
finally
{
lock_.unlock();
}
}
return self_;
}
/*
* This is the fn that should be used to scheule a read repair
* specify a endpoint on whcih the read repair should happen and the row mutaion
* message that has the repaired row.
*/
public void schedule(EndPoint target, RowMutation rm)
{
/*
Message message = new Message(StorageService.getLocalStorageEndPoint(),
StorageService.mutationStage_,
StorageService.readRepairVerbHandler_, new Object[]
{ rowMutationMessage });
*/
try
{
Message message = rm.makeRowMutationMessage(StorageService.readRepairVerbHandler_);
String key = target + ":" + message.getMessageId();
readRepairTable_.put(key, message);
}
catch ( IOException ex )
{
logger_.info(LogUtil.throwableToString(ex));
}
}
}