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ActiveMQ example source code file (Transaction.java)

This example ActiveMQ source code file (Transaction.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

commit, exception, exception, failed, futuretask, futuretask, in_use_state, io, ioexception, ioexception, iterator, start_state, synchronization, threading, threads, util, xaexception, xaexception

The ActiveMQ Transaction.java source code

/**
 * 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 org.apache.activemq.transaction;

import java.io.IOException;
import java.io.InterruptedIOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.FutureTask;
import javax.transaction.xa.XAException;
import org.apache.activemq.command.TransactionId;
import org.slf4j.Logger;

/**
 * Keeps track of all the actions the need to be done when a transaction does a
 * commit or rollback.
 * 
 * 
 */
public abstract class Transaction {

    public static final byte START_STATE = 0; // can go to: 1,2,3
    public static final byte IN_USE_STATE = 1; // can go to: 2,3
    public static final byte PREPARED_STATE = 2; // can go to: 3
    public static final byte FINISHED_STATE = 3;

    private final ArrayList<Synchronization> synchronizations = new ArrayList();
    private byte state = START_STATE;
    protected FutureTask<?> preCommitTask = new FutureTask(new Callable() {
        public Object call() throws Exception {
            doPreCommit();
            return null;
        }   
    });
    protected FutureTask<?> postCommitTask = new FutureTask(new Callable() {
        public Object call() throws Exception {
            doPostCommit();
            return null;
        }   
    });
    
    public byte getState() {
        return state;
    }

    public void setState(byte state) {
        this.state = state;
    }

    public void addSynchronization(Synchronization r) {
        synchronizations.add(r);
        if (state == START_STATE) {
            state = IN_USE_STATE;
        }
    }

    public void removeSynchronization(Synchronization r) {
        synchronizations.remove(r);
    }

    public void prePrepare() throws Exception {

        // Is it ok to call prepare now given the state of the
        // transaction?
        switch (state) {
        case START_STATE:
        case IN_USE_STATE:
            break;
        default:
            XAException xae = new XAException("Prepare cannot be called now.");
            xae.errorCode = XAException.XAER_PROTO;
            throw xae;
        }

        // // Run the prePrepareTasks
        // for (Iterator iter = prePrepareTasks.iterator(); iter.hasNext();) {
        // Callback r = (Callback) iter.next();
        // r.execute();
        // }
    }
    
    protected void fireBeforeCommit() throws Exception {
        for (Iterator<Synchronization> iter = synchronizations.iterator(); iter.hasNext();) {
            Synchronization s = iter.next();
            s.beforeCommit();
        }
    }

    protected void fireAfterCommit() throws Exception {
        for (Iterator<Synchronization> iter = synchronizations.iterator(); iter.hasNext();) {
            Synchronization s = iter.next();
            s.afterCommit();
        }
    }

    public void fireAfterRollback() throws Exception {
    	Collections.reverse(synchronizations);
        for (Iterator<Synchronization> iter = synchronizations.iterator(); iter.hasNext();) {
            Synchronization s = iter.next();
            s.afterRollback();
        }
    }

    @Override
    public String toString() {
        return super.toString() + "[synchronizations=" + synchronizations + "]";
    }

    public abstract void commit(boolean onePhase) throws XAException, IOException;

    public abstract void rollback() throws XAException, IOException;

    public abstract int prepare() throws XAException, IOException;

    public abstract TransactionId getTransactionId();

    public abstract Logger getLog();
    
    public boolean isPrepared() {
        return getState() == PREPARED_STATE;
    }
    
    public int size() {
        return synchronizations.size();
    }
    
    protected void waitPostCommitDone(FutureTask<?> postCommitTask) throws XAException, IOException {
        try {
            postCommitTask.get();
        } catch (InterruptedException e) {
            throw new InterruptedIOException(e.toString());
        } catch (ExecutionException e) {
            Throwable t = e.getCause();
            if (t instanceof XAException) {
                throw (XAException) t;
            } else if (t instanceof IOException) {
                throw (IOException) t;
            } else {
                throw new XAException(e.toString());
            }
        }    
    }
    
    protected void doPreCommit() throws XAException {
        try {
            fireBeforeCommit();
        } catch (Throwable e) {
            // I guess this could happen. Post commit task failed
            // to execute properly.
            getLog().warn("PRE COMMIT FAILED: ", e);
            XAException xae = new XAException("PRE COMMIT FAILED");
            xae.errorCode = XAException.XAER_RMERR;
            xae.initCause(e);
            throw xae;
        }
    }

    protected void doPostCommit() throws XAException {
        try {
            fireAfterCommit();
        } catch (Throwable e) {
            // I guess this could happen. Post commit task failed
            // to execute properly.
            getLog().warn("POST COMMIT FAILED: ", e);
            XAException xae = new XAException("POST COMMIT FAILED");
            xae.errorCode = XAException.XAER_RMERR;
            xae.initCause(e);
            throw xae;
        }
    }
}




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