4089 - IceGrid database corruption.

1 files changed, 135 insertions, 0 deletions

diff --git a/java/src/IceUtilInternal/FileLock.java b/java/src/IceUtilInternal/FileLock.java
new file mode 100644
index 00000000000..46f167ee986
--- /dev/null
+++ b/java/src/IceUtilInternal/FileLock.java
@@ -0,0 +1,135 @@
+// **********************************************************************
+//
+// Copyright (c) 2003-2009 ZeroC, Inc. All rights reserved.
+//
+// This copy of Ice is licensed to you under the terms described in the
+// ICE_LICENSE file included in this distribution.
+//
+// **********************************************************************
+
+package IceUtilInternal;
+
+import java.io.File;
+import java.io.RandomAccessFile;
+import java.io.FileWriter;
+import java.nio.channels.FileChannel;
+import java.nio.channels.OverlappingFileLockException;
+import java.lang.management.ManagementFactory;
+
+public final class FileLock
+{
+    //
+    // The constructor opens the given file (eventually creating it)
+    // and acquires a lock on the file or throws FileLockException if
+    // the file couldn't be locked.
+    //
+    // If the lock can be acquired, the Java VM name is written to the
+    // file.
+    //
+    public FileLock(String path)
+    {
+        _file = new File(path);
+
+        FileChannel channel;
+        try
+        {
+            _randFile = new RandomAccessFile(_file, "rw");
+            channel = _randFile.getChannel();
+        }
+        catch(java.io.FileNotFoundException e)
+        {
+            throw new IceUtil.FileLockException(path);
+        }
+        
+        java.nio.channels.FileLock lock;
+        try
+        {
+            lock = channel.tryLock();
+        }
+        catch(Exception ex)
+        {
+            IceUtil.FileLockException fe = new IceUtil.FileLockException(path);
+            fe.initCause(ex);
+            throw fe;
+        }
+        
+        if(lock == null)
+        {
+            throw new IceUtil.FileLockException(path);
+        }
+
+        //
+        // In Windows we don't write the process pid to the file, as is  not posible
+        // to read the file from other process while it is locked here.
+        //
+        if(!System.getProperty("os.name").startsWith("Windows"))
+        {
+            try
+            {
+                //
+                // Java doesn't provide get pid operation. This code
+                // writes the Java VM name instead of the pid.
+                //
+                // The output is JVM dependent. With the Sun
+                // implementation it's `pid@hostname'
+                //
+                _randFile.writeUTF(ManagementFactory.getRuntimeMXBean().getName());
+
+                //
+                // Don't close _randFile here or the lock will be released. It is called
+                // during release see comments there.
+                //
+            }
+            catch(java.io.IOException ex)
+            {
+                release();
+                throw new IceUtil.FileLockException(path);
+            }
+        }
+    }
+
+    //
+    // Remove the lock if it is owned by the class instance.
+    //
+    public void release()
+    {
+        if(System.getProperty("os.name").startsWith("Windows"))
+        {
+            if(_randFile != null)
+            {
+                //
+                // In Windows we need to close the file handler before
+                // we try to delete the file. Note that the call to close
+                // also release the file lock.
+                //
+                try
+                {
+                    _randFile.close();
+                }
+                catch(java.io.IOException ex)
+                {
+                }
+                _randFile = null;
+            }
+        }
+        //
+        // on UNIX the call to delete remove the file and that
+        // release the lock.
+        //
+        // In Windows the call to delete will success if at that point
+        // the file has not been opened by any process.
+        //
+        if(_file != null)
+        {
+            _file.delete();
+            _file = null;
+        }
+    }
+
+    //
+    // We need to keep these refrences to delete the lock file during release
+    //
+    private File _file;
+    private RandomAccessFile _randFile;
+
+}