Package com.atomikos.persistence.imp

Source Code of com.atomikos.persistence.imp.FileLogStream

/**
* Copyright (C) 2000-2010 Atomikos <info@atomikos.com>
*
* This code ("Atomikos TransactionsEssentials"), by itself,
* is being distributed under the
* Apache License, Version 2.0 ("License"), a copy of which may be found at
* http://www.atomikos.com/licenses/apache-license-2.0.txt .
* You may not use this file except in compliance with the License.
*
* While the License grants certain patent license rights,
* those patent license rights only extend to the use of
* Atomikos TransactionsEssentials by itself.
*
* This code (Atomikos TransactionsEssentials) contains certain interfaces
* in package (namespace) com.atomikos.icatch
* (including com.atomikos.icatch.Participant) which, if implemented, may
* infringe one or more patents held by Atomikos.
* It should be appreciated that you may NOT implement such interfaces;
* licensing to implement these interfaces must be obtained separately from Atomikos.
*
* 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.
*/

package com.atomikos.persistence.imp;

import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.StreamCorruptedException;
import java.util.Enumeration;
import java.util.Vector;

import com.atomikos.logging.Logger;
import com.atomikos.logging.LoggerFactory;
import com.atomikos.persistence.LogException;
import com.atomikos.persistence.LogStream;
import com.atomikos.persistence.Recoverable;

/**
* A file implementation of a LogStream.
*/

public class FileLogStream extends AbstractLogStream implements LogStream {
  private static final Logger LOGGER = LoggerFactory.createLogger(FileLogStream.class);

  // keeps track of the latest output stream returned
  // from writeCheckpoint, so that it can be closed ( invalidated )
  // if necessary.

  private ObjectOutputStream ooutput_;

  private boolean corrupt_;

  // true if error on checkpoint; second call of recover
  // not allowed, otherwise suffix_ will be wrong
  // especially since checkpoint failed.

  public FileLogStream(String baseDir, String baseName) throws IOException {
    super(baseDir, baseName);
  }

  void markAsCorrupt() {
    corrupt_ = true;
  }

  public synchronized Vector<Recoverable> recover() throws LogException {

    if (corrupt_)
      throw new LogException("Instance might be corrupted");

    Vector<Recoverable> ret = new Vector<Recoverable>();
    InputStream in = null;

    try {
      FileInputStream f = file_.openLastValidVersionForReading();

      in = f;

      ObjectInputStream ins = new ObjectInputStream(in);
      int count = 0;
      if (LOGGER.isInfoEnabled()) {
        LOGGER.logInfo("Starting read of logfile " + file_.getCurrentVersionFileName());
      }

      while (in.available() > 0) {
        // if crashed, then unproper closing might cause endless blocking!
        // therefore, we check if avaible first.
        count++;
        Recoverable nxt = (Recoverable) ins.readObject();

        ret.addElement(nxt);
        if (count % 10 == 0) {
          LOGGER.logInfo(".");
        }

      }
      LOGGER.logInfo("Done read of logfile");

    } catch (java.io.EOFException unexpectedEOF) {
      LOGGER.logDebug("Unexpected EOF - logfile not closed properly last time?", unexpectedEOF);
      // merely return what was read so far...
    } catch (StreamCorruptedException unexpectedEOF) {
      LOGGER.logDebug("Unexpected EOF - logfile not closed properly last time?", unexpectedEOF);
      // merely return what was read so far...
    } catch (ObjectStreamException unexpectedEOF) {
      LOGGER.logDebug("Unexpected EOF - logfile not closed properly last time?", unexpectedEOF);
      // merely return what was read so far...
    } catch (FileNotFoundException firstStart) {
      // the file could not be opened for reading;
      // merely return the default empty vector
    } catch (Exception e) {
      String msg = "Error in recover";
      LOGGER.logWarning(msg, e);
      throw new LogException(msg, e);
    } finally {
      try {
        if (in != null)
          in.close();

      } catch (IOException io) {
        throw new LogException("Error in recover", io);
      }
    }

    return ret;
  }

  public synchronized void writeCheckpoint(Enumeration elements) throws LogException {

    // first, make sure that any pending output stream handles
    // in the client are invalidated
    closeOutput();

    try {
      // open the new output file
      // NOTE: after restart, any previous and failed checkpoint files
      // will be overwritten here. That is perfectly OK.
      output_ = file_.openNewVersionForWriting();
      ooutput_ = new ObjectOutputStream(new BufferedOutputStream(output_,4096));
      while (elements != null && elements.hasMoreElements()) {
        Object next = elements.nextElement();
        ooutput_.writeObject(next);
      }
      ooutput_.flush();
      output_.flush();
      output_.getFD().sync();
      // NOTE: we do NOT close the object output, since the client
      // will probably want to write more!
      // Thus, we return the open stream to the client.
      // Any closing will be done later, during cleanup if necessary.

      if (corrupt_) {
        throw new LogException("Instance corrupted");
      }

      try {
        file_.discardBackupVersion();
      } catch (IOException errorOnDelete) {
        markAsCorrupt();
        // should restart
        throw new LogException("Old file could not be deleted");
      }
    } catch (Exception e) {
      throw new LogException("Error during checkpointing", e);
    }

  }

  public synchronized void flushObject(Object o, boolean shouldSync) throws LogException {
    if (ooutput_ == null)
      throw new LogException("Not Initialized or already closed");
    try {
      ooutput_.writeObject(o);
      output_.flush();
      ooutput_.flush();
      if (shouldSync)
        output_.getFD().sync();
    } catch (IOException e) {
      throw new LogException(e.getMessage(), e);
    }
  }

}
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