/*
 * INESC-ID, Instituto de Engenharia de Sistemas e Computadores Investigação e Desevolvimento em Lisboa
 * Copyright 2013 INESC-ID and/or its affiliates and other
 * contributors as indicated by the @author tags. All rights reserved.
 * See the copyright.txt in the distribution for a full listing of
 * individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 3.0 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.infinispan.statetransfer.totalorder;

import org.infinispan.commands.VisitableCommand;
import org.infinispan.commands.tx.CommitCommand;
import org.infinispan.commands.tx.PrepareCommand;
import org.infinispan.commands.tx.RollbackCommand;
import org.infinispan.context.InvocationContext;
import org.infinispan.context.impl.TxInvocationContext;
import org.infinispan.statetransfer.StateTransferLockImpl;
import org.infinispan.util.logging.Log;
import org.infinispan.util.logging.LogFactory;

import java.util.concurrent.TimeoutException;

/**
 * The state transfer lock for Total Order based protocols
 *
 * in the description of the state transfer protocol, the prepares delivered during the state transfer progress
 * should be block until the state transfer ends. In this case we can have 2 options:
 *  - the view is rolled back: the prepare can be processed normally
 *  - the view is committed: the prepare should be retransmitted
 *
 * Note: the commit and rollbacks can pass because they don't change the data
 *       it needs prepare + commit/rollback and the prepares are blocked :)
 *
 * @author Pedro Ruivo
 * @since 5.2
 */
public class TotalOrderStateTransferLockImpl extends StateTransferLockImpl {
   private static final Log log = LogFactory.getLog(TotalOrderStateTransferLockImpl.class);

   @Override
   public boolean acquireForCommand(TxInvocationContext ctx, PrepareCommand command) throws InterruptedException, TimeoutException {
      //NOTE the semantic of acquireForCommand is a little different now!!
      waitForStateTransferToEnd();
      return true;
   }

   @Override
   public void releaseForCommand(TxInvocationContext ctx, PrepareCommand command) {
      //no-op
   }

   /**
    * it blocks prepares if the state transfer is in progress and the prepare has the same cache view than the current
    * cache view (see class description). The prepare is unblocked when the state transfer is finished
    *
    * this method does nothing if no state transfer is in progress.
    *
    * @throws InterruptedException
    */
   private void waitForStateTransferToEnd() throws InterruptedException {
      synchronized (lock) {
         while (areNewTransactionsBlocked()) {
            log.tracef("blocking thread until the until the state transfer has finished");
            lock.wait();
         }
      }
      log.tracef("No state transfer or state transfer has finished. move on...");
   }

   @Override
   public void waitForStateTransferToEnd(InvocationContext ctx, VisitableCommand command, int newCacheViewId) throws TimeoutException, InterruptedException {
      if (command instanceof PrepareCommand || command instanceof CommitCommand || command instanceof RollbackCommand) {
         return; //the prepare commands does not acquire the lock
      }
      super.waitForStateTransferToEnd(ctx, command, newCacheViewId);
   }
}