Mercurial > hg > blitz_stable
diff src/org/prevayler/implementation/CommandInputStream.java @ 0:3dc0c5604566
Initial checkin of blitz 2.0 fcs - no installer yet.
author | Dan Creswell <dan.creswell@gmail.com> |
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date | Sat, 21 Mar 2009 11:00:06 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/org/prevayler/implementation/CommandInputStream.java Sat Mar 21 11:00:06 2009 +0000 @@ -0,0 +1,109 @@ +/* + The copyright of all source code included in this Prevayler distribution is + held by Klaus Wuestefeld, except the files that specifically state otherwise. + All rights are reserved. "PREVAYLER" is a trademark of Klaus Wuestefeld. + + + BSD License: + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions are met: + + - Redistributions of source code must retain the above copyright notice, this + list of conditions and the following disclaimer. + + - Redistributions in binary form must reproduce the above copyright notice, + this list of conditions and the following disclaimer in the documentation + and/or other materials provided with the distribution. + + - Neither the name of Prevayler nor the names of its contributors may be used + to endorse or promote products derived from this software without specific + prior written permission. + + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + POSSIBILITY OF SUCH DAMAGE. +*/ + +package org.prevayler.implementation; + +import java.io.*; +import org.prevayler.*; + +/** Provides an easy API for reading commands and snapshots. +*/ +class CommandInputStream { + + public CommandInputStream(String directory) throws IOException { + fileFinder = new NumberFileFinder(directory); + } + + public PrevalentSystem readLastSnapshot() throws IOException, ClassNotFoundException { + File snapshotFile = fileFinder.lastSnapshot(); + if (snapshotFile == null) return null; + out(snapshotFile); + + ObjectInputStream ois = new ObjectInputStream(new FileInputStream(snapshotFile)); + try { + return (PrevalentSystem)ois.readObject(); + } finally { + ois.close(); + } + } + + public Command readCommand() throws IOException, ClassNotFoundException { + if (currentLogStream == null) currentLogStream = newLogStream(); //Throws EOFException if there are no more log streams. + + try { + return (Command)currentLogStream.readObject(); + } catch (EOFException eof) { + //No more commands in this file. + } catch (ObjectStreamException osx) { + logStreamExceptionMessage(osx); + } catch (RuntimeException rx) { + logStreamExceptionMessage(rx); //Some stream corruptions cause runtime exceptions! + } + + currentLogStream.close(); + currentLogStream = null; + return readCommand(); + } + + public CommandOutputStream commandOutputStream(boolean shouldReset, + boolean shouldClean, + int aBufferSize) { + return new CommandOutputStream(fileFinder.fileCreator(), shouldReset, + shouldClean, aBufferSize); + } + + private ObjectInputStream newLogStream() throws IOException { + File logFile = fileFinder.nextPendingLog(); //Throws EOFException if there are no more pending log files. + out(logFile); + return new ObjectInputStream(new BufferedInputStream(new FileInputStream(logFile))); + } + + private void logStreamExceptionMessage(Exception exception) { + out(" " + exception); + out(" Some commands might have been lost. Looking for the next file..." ); + } + + private static void out(File file) { + out("Reading: " + file + "..."); + } + + private static void out(Object obj) { + System.out.println(obj); + } + + private NumberFileFinder fileFinder; + private ObjectInputStream currentLogStream; +}