author | khazra |
Fri, 02 Mar 2012 13:48:43 -0800 | |
changeset 12040 | 558b0e0d5910 |
parent 9502 | de183d393b77 |
child 14342 | 8435a30053c1 |
permissions | -rw-r--r-- |
2 | 1 |
/* |
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* Copyright (c) 1997, 2008, Oracle and/or its affiliates. All rights reserved. |
2 | 3 |
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
|
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package sun.rmi.log; |
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import java.io.*; |
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import java.lang.reflect.Constructor; |
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import java.rmi.server.RMIClassLoader; |
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import java.security.AccessController; |
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import java.security.PrivilegedAction; |
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import sun.security.action.GetBooleanAction; |
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import sun.security.action.GetPropertyAction; |
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/** |
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* This class is a simple implementation of a reliable Log. The |
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* client of a ReliableLog must provide a set of callbacks (via a |
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* LogHandler) that enables a ReliableLog to read and write |
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* checkpoints and log records. This implementation ensures that the |
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* current value of the data stored (via a ReliableLog) is recoverable |
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* after a system crash. <p> |
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* |
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* The secondary storage strategy is to record values in files using a |
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* representation of the caller's choosing. Two sorts of files are |
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* kept: snapshots and logs. At any instant, one snapshot is current. |
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* The log consists of a sequence of updates that have occurred since |
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* the current snapshot was taken. The current stable state is the |
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* value of the snapshot, as modified by the sequence of updates in |
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* the log. From time to time, the client of a ReliableLog instructs |
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* the package to make a new snapshot and clear the log. A ReliableLog |
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* arranges disk writes such that updates are stable (as long as the |
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* changes are force-written to disk) and atomic : no update is lost, |
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* and each update either is recorded completely in the log or not at |
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* all. Making a new snapshot is also atomic. <p> |
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* |
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* Normal use for maintaining the recoverable store is as follows: The |
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* client maintains the relevant data structure in virtual memory. As |
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* updates happen to the structure, the client informs the ReliableLog |
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* (all it "log") by calling log.update. Periodically, the client |
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* calls log.snapshot to provide the current value of the data |
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* structure. On restart, the client calls log.recover to obtain the |
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* latest snapshot and the following sequences of updates; the client |
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* applies the updates to the snapshot to obtain the state that |
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* existed before the crash. <p> |
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* |
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* The current logfile format is: <ol> |
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* <li> a format version number (two 4-octet integers, major and |
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* minor), followed by |
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* <li> a sequence of log records. Each log record contains, in |
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* order, <ol> |
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* <li> a 4-octet integer representing the length of the following log |
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* data, |
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* <li> the log data (variable length). </ol> </ol> <p> |
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* |
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* @see LogHandler |
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* |
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* @author Ann Wollrath |
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* |
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*/ |
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public class ReliableLog { |
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public final static int PreferredMajorVersion = 0; |
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public final static int PreferredMinorVersion = 2; |
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// sun.rmi.log.debug=false |
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private boolean Debug = false; |
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private static String snapshotPrefix = "Snapshot."; |
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private static String logfilePrefix = "Logfile."; |
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private static String versionFile = "Version_Number"; |
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private static String newVersionFile = "New_Version_Number"; |
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private static int intBytes = 4; |
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private static long diskPageSize = 512; |
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private File dir; // base directory |
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private int version = 0; // current snapshot and log version |
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private String logName = null; |
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private LogFile log = null; |
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private long snapshotBytes = 0; |
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private long logBytes = 0; |
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private int logEntries = 0; |
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private long lastSnapshot = 0; |
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private long lastLog = 0; |
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//private long padBoundary = intBytes; |
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private LogHandler handler; |
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private final byte[] intBuf = new byte[4]; |
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// format version numbers read from/written to this.log |
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private int majorFormatVersion = 0; |
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private int minorFormatVersion = 0; |
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/** |
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* Constructor for the log file. If the system property |
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* sun.rmi.log.class is non-null and the class specified by this |
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* property a) can be loaded, b) is a subclass of LogFile, and c) has a |
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* public two-arg constructor (String, String), ReliableLog uses the |
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* constructor to construct the LogFile. |
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**/ |
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private static final Constructor<? extends LogFile> |
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logClassConstructor = getLogClassConstructor(); |
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/** |
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* Creates a ReliableLog to handle checkpoints and logging in a |
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* stable storage directory. |
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* |
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* @param dirPath path to the stable storage directory |
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* @param logCl the closure object containing callbacks for logging and |
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* recovery |
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* @param pad ignored |
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* @exception IOException If a directory creation error has |
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* occurred or if initialSnapshot callback raises an exception or |
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* if an exception occurs during invocation of the handler's |
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* snapshot method or if other IOException occurs. |
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*/ |
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public ReliableLog(String dirPath, |
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LogHandler handler, |
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boolean pad) |
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throws IOException |
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{ |
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super(); |
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this.Debug = AccessController.doPrivileged( |
144 |
new GetBooleanAction("sun.rmi.log.debug")).booleanValue(); |
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dir = new File(dirPath); |
146 |
if (!(dir.exists() && dir.isDirectory())) { |
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// create directory |
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148 |
if (!dir.mkdir()) { |
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149 |
throw new IOException("could not create directory for log: " + |
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dirPath); |
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} |
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} |
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//padBoundary = (pad ? diskPageSize : intBytes); |
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this.handler = handler; |
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lastSnapshot = 0; |
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lastLog = 0; |
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getVersion(); |
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if (version == 0) { |
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try { |
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snapshot(handler.initialSnapshot()); |
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} catch (IOException e) { |
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throw e; |
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} catch (Exception e) { |
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throw new IOException("initial snapshot failed with " + |
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"exception: " + e); |
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} |
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} |
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} |
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/** |
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* Creates a ReliableLog to handle checkpoints and logging in a |
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* stable storage directory. |
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* |
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* @param dirPath path to the stable storage directory |
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* @param logCl the closure object containing callbacks for logging and |
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* recovery |
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* @exception IOException If a directory creation error has |
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* occurred or if initialSnapshot callback raises an exception |
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*/ |
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public ReliableLog(String dirPath, |
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LogHandler handler) |
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throws IOException |
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{ |
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this(dirPath, handler, false); |
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} |
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/* public methods */ |
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189 |
/** |
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* Returns an object which is the value recorded in the current |
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* snapshot. This snapshot is recovered by calling the client |
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* supplied callback "recover" and then subsequently invoking |
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* the "readUpdate" callback to apply any logged updates to the state. |
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* |
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* @exception IOException If recovery fails due to serious log |
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* corruption, read update failure, or if an exception occurs |
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* during the recover callback |
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*/ |
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public synchronized Object recover() |
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throws IOException |
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{ |
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if (Debug) |
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System.err.println("log.debug: recover()"); |
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205 |
if (version == 0) |
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return null; |
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Object snapshot; |
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String fname = versionName(snapshotPrefix); |
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File snapshotFile = new File(fname); |
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InputStream in = |
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new BufferedInputStream(new FileInputStream(snapshotFile)); |
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if (Debug) |
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System.err.println("log.debug: recovering from " + fname); |
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217 |
try { |
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try { |
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snapshot = handler.recover(in); |
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} catch (IOException e) { |
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throw e; |
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} catch (Exception e) { |
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if (Debug) |
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System.err.println("log.debug: recovery failed: " + e); |
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throw new IOException("log recover failed with " + |
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"exception: " + e); |
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} |
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snapshotBytes = snapshotFile.length(); |
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} finally { |
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in.close(); |
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} |
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return recoverUpdates(snapshot); |
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} |
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/** |
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* Records this update in the log file (does not force update to disk). |
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* The update is recorded by calling the client's "writeUpdate" callback. |
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* This method must not be called until this log's recover method has |
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* been invoked (and completed). |
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* |
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* @param value the object representing the update |
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* @exception IOException If an exception occurred during a |
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* writeUpdate callback or if other I/O error has occurred. |
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*/ |
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public synchronized void update(Object value) throws IOException { |
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update(value, true); |
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} |
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250 |
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251 |
/** |
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* Records this update in the log file. The update is recorded by |
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* calling the client's writeUpdate callback. This method must not be |
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* called until this log's recover method has been invoked |
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* (and completed). |
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* |
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* @param value the object representing the update |
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* @param forceToDisk ignored; changes are always forced to disk |
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* @exception IOException If force-write to log failed or an |
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* exception occurred during the writeUpdate callback or if other |
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* I/O error occurs while updating the log. |
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*/ |
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public synchronized void update(Object value, boolean forceToDisk) |
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throws IOException |
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{ |
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266 |
// avoid accessing a null log field. |
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267 |
if (log == null) { |
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throw new IOException("log is inaccessible, " + |
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"it may have been corrupted or closed"); |
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} |
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272 |
/* |
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273 |
* If the entry length field spans a sector boundary, write |
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* the high order bit of the entry length, otherwise write zero for |
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* the entry length. |
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*/ |
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277 |
long entryStart = log.getFilePointer(); |
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boolean spansBoundary = log.checkSpansBoundary(entryStart); |
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writeInt(log, spansBoundary? 1<<31 : 0); |
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280 |
||
281 |
/* |
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282 |
* Write update, and sync. |
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*/ |
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284 |
try { |
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handler.writeUpdate(new LogOutputStream(log), value); |
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} catch (IOException e) { |
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throw e; |
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288 |
} catch (Exception e) { |
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throw (IOException) |
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new IOException("write update failed").initCause(e); |
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} |
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log.sync(); |
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||
294 |
long entryEnd = log.getFilePointer(); |
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int updateLen = (int) ((entryEnd - entryStart) - intBytes); |
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296 |
log.seek(entryStart); |
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297 |
||
298 |
if (spansBoundary) { |
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299 |
/* |
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300 |
* If length field spans a sector boundary, then |
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* the next two steps are required (see 4652922): |
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302 |
* |
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303 |
* 1) Write actual length with high order bit set; sync. |
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304 |
* 2) Then clear high order bit of length; sync. |
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305 |
*/ |
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306 |
writeInt(log, updateLen | 1<<31); |
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307 |
log.sync(); |
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308 |
||
309 |
log.seek(entryStart); |
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310 |
log.writeByte(updateLen >> 24); |
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311 |
log.sync(); |
|
312 |
||
313 |
} else { |
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314 |
/* |
|
315 |
* Write actual length; sync. |
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316 |
*/ |
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317 |
writeInt(log, updateLen); |
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318 |
log.sync(); |
|
319 |
} |
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320 |
||
321 |
log.seek(entryEnd); |
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322 |
logBytes = entryEnd; |
|
323 |
lastLog = System.currentTimeMillis(); |
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324 |
logEntries++; |
|
325 |
} |
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326 |
||
327 |
/** |
|
328 |
* Returns the constructor for the log file if the system property |
|
329 |
* sun.rmi.log.class is non-null and the class specified by the |
|
330 |
* property a) can be loaded, b) is a subclass of LogFile, and c) has a |
|
331 |
* public two-arg constructor (String, String); otherwise returns null. |
|
332 |
**/ |
|
333 |
private static Constructor<? extends LogFile> |
|
334 |
getLogClassConstructor() { |
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335 |
||
51 | 336 |
String logClassName = AccessController.doPrivileged( |
337 |
new GetPropertyAction("sun.rmi.log.class")); |
|
2 | 338 |
if (logClassName != null) { |
339 |
try { |
|
340 |
ClassLoader loader = |
|
341 |
AccessController.doPrivileged( |
|
342 |
new PrivilegedAction<ClassLoader>() { |
|
343 |
public ClassLoader run() { |
|
344 |
return ClassLoader.getSystemClassLoader(); |
|
345 |
} |
|
346 |
}); |
|
12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
347 |
Class<? extends LogFile> cl = |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
348 |
loader.loadClass(logClassName).asSubclass(LogFile.class); |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
349 |
return cl.getConstructor(String.class, String.class); |
2 | 350 |
} catch (Exception e) { |
351 |
System.err.println("Exception occurred:"); |
|
352 |
e.printStackTrace(); |
|
353 |
} |
|
354 |
} |
|
355 |
return null; |
|
356 |
} |
|
357 |
||
358 |
/** |
|
359 |
* Records this value as the current snapshot by invoking the client |
|
360 |
* supplied "snapshot" callback and then empties the log. |
|
361 |
* |
|
362 |
* @param value the object representing the new snapshot |
|
363 |
* @exception IOException If an exception occurred during the |
|
364 |
* snapshot callback or if other I/O error has occurred during the |
|
365 |
* snapshot process |
|
366 |
*/ |
|
367 |
public synchronized void snapshot(Object value) |
|
368 |
throws IOException |
|
369 |
{ |
|
370 |
int oldVersion = version; |
|
371 |
incrVersion(); |
|
372 |
||
373 |
String fname = versionName(snapshotPrefix); |
|
374 |
File snapshotFile = new File(fname); |
|
375 |
FileOutputStream out = new FileOutputStream(snapshotFile); |
|
376 |
try { |
|
377 |
try { |
|
378 |
handler.snapshot(out, value); |
|
379 |
} catch (IOException e) { |
|
380 |
throw e; |
|
381 |
} catch (Exception e) { |
|
9502
de183d393b77
6896297: (rmi) fix ConcurrentModificationException causing TCK failure
smarks
parents:
5506
diff
changeset
|
382 |
throw new IOException("snapshot failed", e); |
2 | 383 |
} |
384 |
lastSnapshot = System.currentTimeMillis(); |
|
385 |
} finally { |
|
386 |
out.close(); |
|
387 |
snapshotBytes = snapshotFile.length(); |
|
388 |
} |
|
389 |
||
390 |
openLogFile(true); |
|
391 |
writeVersionFile(true); |
|
392 |
commitToNewVersion(); |
|
393 |
deleteSnapshot(oldVersion); |
|
394 |
deleteLogFile(oldVersion); |
|
395 |
} |
|
396 |
||
397 |
/** |
|
398 |
* Close the stable storage directory in an orderly manner. |
|
399 |
* |
|
400 |
* @exception IOException If an I/O error occurs when the log is |
|
401 |
* closed |
|
402 |
*/ |
|
403 |
public synchronized void close() throws IOException { |
|
404 |
if (log == null) return; |
|
405 |
try { |
|
406 |
log.close(); |
|
407 |
} finally { |
|
408 |
log = null; |
|
409 |
} |
|
410 |
} |
|
411 |
||
412 |
/** |
|
413 |
* Returns the size of the snapshot file in bytes; |
|
414 |
*/ |
|
415 |
public long snapshotSize() { |
|
416 |
return snapshotBytes; |
|
417 |
} |
|
418 |
||
419 |
/** |
|
420 |
* Returns the size of the log file in bytes; |
|
421 |
*/ |
|
422 |
public long logSize() { |
|
423 |
return logBytes; |
|
424 |
} |
|
425 |
||
426 |
/* private methods */ |
|
427 |
||
428 |
/** |
|
429 |
* Write an int value in single write operation. This method |
|
430 |
* assumes that the caller is synchronized on the log file. |
|
431 |
* |
|
432 |
* @param out output stream |
|
433 |
* @param val int value |
|
434 |
* @throws IOException if any other I/O error occurs |
|
435 |
*/ |
|
436 |
private void writeInt(DataOutput out, int val) |
|
437 |
throws IOException |
|
438 |
{ |
|
439 |
intBuf[0] = (byte) (val >> 24); |
|
440 |
intBuf[1] = (byte) (val >> 16); |
|
441 |
intBuf[2] = (byte) (val >> 8); |
|
442 |
intBuf[3] = (byte) val; |
|
443 |
out.write(intBuf); |
|
444 |
} |
|
445 |
||
446 |
/** |
|
447 |
* Generates a filename prepended with the stable storage directory path. |
|
448 |
* |
|
449 |
* @param name the leaf name of the file |
|
450 |
*/ |
|
451 |
private String fName(String name) { |
|
452 |
return dir.getPath() + File.separator + name; |
|
453 |
} |
|
454 |
||
455 |
/** |
|
456 |
* Generates a version 0 filename prepended with the stable storage |
|
457 |
* directory path |
|
458 |
* |
|
459 |
* @param name version file name |
|
460 |
*/ |
|
461 |
private String versionName(String name) { |
|
462 |
return versionName(name, 0); |
|
463 |
} |
|
464 |
||
465 |
/** |
|
466 |
* Generates a version filename prepended with the stable storage |
|
467 |
* directory path with the version number as a suffix. |
|
468 |
* |
|
469 |
* @param name version file name |
|
470 |
* @thisversion a version number |
|
471 |
*/ |
|
472 |
private String versionName(String prefix, int ver) { |
|
473 |
ver = (ver == 0) ? version : ver; |
|
474 |
return fName(prefix) + String.valueOf(ver); |
|
475 |
} |
|
476 |
||
477 |
/** |
|
478 |
* Increments the directory version number. |
|
479 |
*/ |
|
480 |
private void incrVersion() { |
|
481 |
do { version++; } while (version==0); |
|
482 |
} |
|
483 |
||
484 |
/** |
|
485 |
* Delete a file. |
|
486 |
* |
|
487 |
* @param name the name of the file |
|
488 |
* @exception IOException If new version file couldn't be removed |
|
489 |
*/ |
|
490 |
private void deleteFile(String name) throws IOException { |
|
491 |
||
492 |
File f = new File(name); |
|
493 |
if (!f.delete()) |
|
494 |
throw new IOException("couldn't remove file: " + name); |
|
495 |
} |
|
496 |
||
497 |
/** |
|
498 |
* Removes the new version number file. |
|
499 |
* |
|
500 |
* @exception IOException If an I/O error has occurred. |
|
501 |
*/ |
|
502 |
private void deleteNewVersionFile() throws IOException { |
|
503 |
deleteFile(fName(newVersionFile)); |
|
504 |
} |
|
505 |
||
506 |
/** |
|
507 |
* Removes the snapshot file. |
|
508 |
* |
|
509 |
* @param ver the version to remove |
|
510 |
* @exception IOException If an I/O error has occurred. |
|
511 |
*/ |
|
512 |
private void deleteSnapshot(int ver) throws IOException { |
|
513 |
if (ver == 0) return; |
|
514 |
deleteFile(versionName(snapshotPrefix, ver)); |
|
515 |
} |
|
516 |
||
517 |
/** |
|
518 |
* Removes the log file. |
|
519 |
* |
|
520 |
* @param ver the version to remove |
|
521 |
* @exception IOException If an I/O error has occurred. |
|
522 |
*/ |
|
523 |
private void deleteLogFile(int ver) throws IOException { |
|
524 |
if (ver == 0) return; |
|
525 |
deleteFile(versionName(logfilePrefix, ver)); |
|
526 |
} |
|
527 |
||
528 |
/** |
|
529 |
* Opens the log file in read/write mode. If file does not exist, it is |
|
530 |
* created. |
|
531 |
* |
|
532 |
* @param truncate if true and file exists, file is truncated to zero |
|
533 |
* length |
|
534 |
* @exception IOException If an I/O error has occurred. |
|
535 |
*/ |
|
536 |
private void openLogFile(boolean truncate) throws IOException { |
|
537 |
try { |
|
538 |
close(); |
|
539 |
} catch (IOException e) { /* assume this is okay */ |
|
540 |
} |
|
541 |
||
542 |
logName = versionName(logfilePrefix); |
|
543 |
||
544 |
try { |
|
545 |
log = (logClassConstructor == null ? |
|
546 |
new LogFile(logName, "rw") : |
|
547 |
logClassConstructor.newInstance(logName, "rw")); |
|
548 |
} catch (Exception e) { |
|
549 |
throw (IOException) new IOException( |
|
550 |
"unable to construct LogFile instance").initCause(e); |
|
551 |
} |
|
552 |
||
553 |
if (truncate) { |
|
554 |
initializeLogFile(); |
|
555 |
} |
|
556 |
} |
|
557 |
||
558 |
/** |
|
559 |
* Creates a new log file, truncated and initialized with the format |
|
560 |
* version number preferred by this implementation. |
|
561 |
* <p>Environment: inited, synchronized |
|
562 |
* <p>Precondition: valid: log, log contains nothing useful |
|
563 |
* <p>Postcondition: if successful, log is initialised with the format |
|
564 |
* version number (Preferred{Major,Minor}Version), and logBytes is |
|
565 |
* set to the resulting size of the updatelog, and logEntries is set to |
|
566 |
* zero. Otherwise, log is in an indeterminate state, and logBytes |
|
567 |
* is unchanged, and logEntries is unchanged. |
|
568 |
* |
|
569 |
* @exception IOException If an I/O error has occurred. |
|
570 |
*/ |
|
571 |
private void initializeLogFile() |
|
572 |
throws IOException |
|
573 |
{ |
|
574 |
log.setLength(0); |
|
575 |
majorFormatVersion = PreferredMajorVersion; |
|
576 |
writeInt(log, PreferredMajorVersion); |
|
577 |
minorFormatVersion = PreferredMinorVersion; |
|
578 |
writeInt(log, PreferredMinorVersion); |
|
579 |
logBytes = intBytes * 2; |
|
580 |
logEntries = 0; |
|
581 |
} |
|
582 |
||
583 |
||
584 |
/** |
|
585 |
* Writes out version number to file. |
|
586 |
* |
|
587 |
* @param newVersion if true, writes to a new version file |
|
588 |
* @exception IOException If an I/O error has occurred. |
|
589 |
*/ |
|
590 |
private void writeVersionFile(boolean newVersion) throws IOException { |
|
591 |
String name; |
|
592 |
if (newVersion) { |
|
593 |
name = newVersionFile; |
|
594 |
} else { |
|
595 |
name = versionFile; |
|
596 |
} |
|
12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
597 |
try (FileOutputStream fos = new FileOutputStream(fName(name)); |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
598 |
DataOutputStream out = new DataOutputStream(fos)) { |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
599 |
writeInt(out, version); |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
600 |
} |
2 | 601 |
} |
602 |
||
603 |
/** |
|
604 |
* Creates the initial version file |
|
605 |
* |
|
606 |
* @exception IOException If an I/O error has occurred. |
|
607 |
*/ |
|
608 |
private void createFirstVersion() throws IOException { |
|
609 |
version = 0; |
|
610 |
writeVersionFile(false); |
|
611 |
} |
|
612 |
||
613 |
/** |
|
614 |
* Commits (atomically) the new version. |
|
615 |
* |
|
616 |
* @exception IOException If an I/O error has occurred. |
|
617 |
*/ |
|
618 |
private void commitToNewVersion() throws IOException { |
|
619 |
writeVersionFile(false); |
|
620 |
deleteNewVersionFile(); |
|
621 |
} |
|
622 |
||
623 |
/** |
|
624 |
* Reads version number from a file. |
|
625 |
* |
|
626 |
* @param name the name of the version file |
|
627 |
* @return the version |
|
628 |
* @exception IOException If an I/O error has occurred. |
|
629 |
*/ |
|
630 |
private int readVersion(String name) throws IOException { |
|
12040
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
631 |
try (DataInputStream in = new DataInputStream |
558b0e0d5910
7146763: Warnings cleanup in the sun.rmi and related packages
khazra
parents:
9502
diff
changeset
|
632 |
(new FileInputStream(name))) { |
2 | 633 |
return in.readInt(); |
634 |
} |
|
635 |
} |
|
636 |
||
637 |
/** |
|
638 |
* Sets the version. If version file does not exist, the initial |
|
639 |
* version file is created. |
|
640 |
* |
|
641 |
* @exception IOException If an I/O error has occurred. |
|
642 |
*/ |
|
643 |
private void getVersion() throws IOException { |
|
644 |
try { |
|
645 |
version = readVersion(fName(newVersionFile)); |
|
646 |
commitToNewVersion(); |
|
647 |
} catch (IOException e) { |
|
648 |
try { |
|
649 |
deleteNewVersionFile(); |
|
650 |
} |
|
651 |
catch (IOException ex) { |
|
652 |
} |
|
653 |
||
654 |
try { |
|
655 |
version = readVersion(fName(versionFile)); |
|
656 |
} |
|
657 |
catch (IOException ex) { |
|
658 |
createFirstVersion(); |
|
659 |
} |
|
660 |
} |
|
661 |
} |
|
662 |
||
663 |
/** |
|
664 |
* Applies outstanding updates to the snapshot. |
|
665 |
* |
|
666 |
* @param state the most recent snapshot |
|
667 |
* @exception IOException If serious log corruption is detected or |
|
668 |
* if an exception occurred during a readUpdate callback or if |
|
669 |
* other I/O error has occurred. |
|
670 |
* @return the resulting state of the object after all updates |
|
671 |
*/ |
|
672 |
private Object recoverUpdates(Object state) |
|
673 |
throws IOException |
|
674 |
{ |
|
675 |
logBytes = 0; |
|
676 |
logEntries = 0; |
|
677 |
||
678 |
if (version == 0) return state; |
|
679 |
||
680 |
String fname = versionName(logfilePrefix); |
|
681 |
InputStream in = |
|
682 |
new BufferedInputStream(new FileInputStream(fname)); |
|
683 |
DataInputStream dataIn = new DataInputStream(in); |
|
684 |
||
685 |
if (Debug) |
|
686 |
System.err.println("log.debug: reading updates from " + fname); |
|
687 |
||
688 |
try { |
|
689 |
majorFormatVersion = dataIn.readInt(); logBytes += intBytes; |
|
690 |
minorFormatVersion = dataIn.readInt(); logBytes += intBytes; |
|
691 |
} catch (EOFException e) { |
|
692 |
/* This is a log which was corrupted and/or cleared (by |
|
693 |
* fsck or equivalent). This is not an error. |
|
694 |
*/ |
|
695 |
openLogFile(true); // create and truncate |
|
696 |
in = null; |
|
697 |
} |
|
698 |
/* A new major version number is a catastrophe (it means |
|
699 |
* that the file format is incompatible with older |
|
700 |
* clients, and we'll only be breaking things by trying to |
|
701 |
* use the log). A new minor version is no big deal for |
|
702 |
* upward compatibility. |
|
703 |
*/ |
|
704 |
if (majorFormatVersion != PreferredMajorVersion) { |
|
705 |
if (Debug) { |
|
706 |
System.err.println("log.debug: major version mismatch: " + |
|
707 |
majorFormatVersion + "." + minorFormatVersion); |
|
708 |
} |
|
709 |
throw new IOException("Log file " + logName + " has a " + |
|
710 |
"version " + majorFormatVersion + |
|
711 |
"." + minorFormatVersion + |
|
712 |
" format, and this implementation " + |
|
713 |
" understands only version " + |
|
714 |
PreferredMajorVersion + "." + |
|
715 |
PreferredMinorVersion); |
|
716 |
} |
|
717 |
||
718 |
try { |
|
719 |
while (in != null) { |
|
720 |
int updateLen = 0; |
|
721 |
||
722 |
try { |
|
723 |
updateLen = dataIn.readInt(); |
|
724 |
} catch (EOFException e) { |
|
725 |
if (Debug) |
|
726 |
System.err.println("log.debug: log was sync'd cleanly"); |
|
727 |
break; |
|
728 |
} |
|
729 |
if (updateLen <= 0) {/* crashed while writing last log entry */ |
|
730 |
if (Debug) { |
|
731 |
System.err.println( |
|
732 |
"log.debug: last update incomplete, " + |
|
733 |
"updateLen = 0x" + |
|
734 |
Integer.toHexString(updateLen)); |
|
735 |
} |
|
736 |
break; |
|
737 |
} |
|
738 |
||
739 |
// this is a fragile use of available() which relies on the |
|
740 |
// twin facts that BufferedInputStream correctly consults |
|
741 |
// the underlying stream, and that FileInputStream returns |
|
742 |
// the number of bytes remaining in the file (via FIONREAD). |
|
743 |
if (in.available() < updateLen) { |
|
744 |
/* corrupted record at end of log (can happen since we |
|
745 |
* do only one fsync) |
|
746 |
*/ |
|
747 |
if (Debug) |
|
748 |
System.err.println("log.debug: log was truncated"); |
|
749 |
break; |
|
750 |
} |
|
751 |
||
752 |
if (Debug) |
|
753 |
System.err.println("log.debug: rdUpdate size " + updateLen); |
|
754 |
try { |
|
755 |
state = handler.readUpdate(new LogInputStream(in, updateLen), |
|
756 |
state); |
|
757 |
} catch (IOException e) { |
|
758 |
throw e; |
|
759 |
} catch (Exception e) { |
|
760 |
e.printStackTrace(); |
|
761 |
throw new IOException("read update failed with " + |
|
762 |
"exception: " + e); |
|
763 |
} |
|
764 |
logBytes += (intBytes + updateLen); |
|
765 |
logEntries++; |
|
766 |
} /* while */ |
|
767 |
} finally { |
|
768 |
if (in != null) |
|
769 |
in.close(); |
|
770 |
} |
|
771 |
||
772 |
if (Debug) |
|
773 |
System.err.println("log.debug: recovered updates: " + logEntries); |
|
774 |
||
775 |
/* reopen log file at end */ |
|
776 |
openLogFile(false); |
|
777 |
||
778 |
// avoid accessing a null log field |
|
779 |
if (log == null) { |
|
780 |
throw new IOException("rmid's log is inaccessible, " + |
|
781 |
"it may have been corrupted or closed"); |
|
782 |
} |
|
783 |
||
784 |
log.seek(logBytes); |
|
785 |
log.setLength(logBytes); |
|
786 |
||
787 |
return state; |
|
788 |
} |
|
789 |
||
790 |
/** |
|
791 |
* ReliableLog's log file implementation. This implementation |
|
792 |
* is subclassable for testing purposes. |
|
793 |
*/ |
|
794 |
public static class LogFile extends RandomAccessFile { |
|
795 |
||
796 |
private final FileDescriptor fd; |
|
797 |
||
798 |
/** |
|
799 |
* Constructs a LogFile and initializes the file descriptor. |
|
800 |
**/ |
|
801 |
public LogFile(String name, String mode) |
|
802 |
throws FileNotFoundException, IOException |
|
803 |
{ |
|
804 |
super(name, mode); |
|
805 |
this.fd = getFD(); |
|
806 |
} |
|
807 |
||
808 |
/** |
|
809 |
* Invokes sync on the file descriptor for this log file. |
|
810 |
*/ |
|
811 |
protected void sync() throws IOException { |
|
812 |
fd.sync(); |
|
813 |
} |
|
814 |
||
815 |
/** |
|
816 |
* Returns true if writing 4 bytes starting at the specified file |
|
817 |
* position, would span a 512 byte sector boundary; otherwise returns |
|
818 |
* false. |
|
819 |
**/ |
|
820 |
protected boolean checkSpansBoundary(long fp) { |
|
821 |
return fp % 512 > 508; |
|
822 |
} |
|
823 |
} |
|
824 |
} |