[jira] Resolved: (HARMONY-246) java.nio.channels.FileChannel.tryLock() should be non-blocking

["Tim Ellison (JIRA)" <ji...@apache.org>]

     [ http://issues.apache.org/jira/browse/HARMONY-246?page=all ]
     
Tim Ellison resolved HARMONY-246:
---------------------------------

    Resolution: Fixed

Anton

Fixed in NIO module at repo revision 396908.

Please check that this fully resolves your problem.


> java.nio.channels.FileChannel.tryLock() should be non-blocking
> --------------------------------------------------------------
>
>          Key: HARMONY-246
>          URL: http://issues.apache.org/jira/browse/HARMONY-246
>      Project: Harmony
>         Type: Bug

>   Components: Classlib
>  Environment: Windows, Linux
>     Reporter: Anton Luht
>     Assignee: Tim Ellison
>  Attachments: Harmony-246.txt
>
> j2se 1.4.2 spec for java.nio.channels.FileChannel says: 
> tryLock(..) 
> Attempts to acquire a lock on the given region of this channel's file. 
> This method does not block. An invocation of this always returns immediately, either having acquired a lock on the requested region or having failed to do so. If it fails to acquire a lock because an overlapping lock is held by another program then it returns null. If it fails to acquire a lock for any other reason then an appropriate exception is thrown. 
> in Harmony code this method blocks 
> Suggested fix (naive): always use O_NONBLOCK in fcntl
> Code to reproduce:
> import java.io.*;
> public class Test {
>   public static void main(String args[]) throws Exception {
>      File f = new File("abcd");
>      f.deleteOnExit();
>    
>      new FileOutputStream(f, true).getChannel().tryLock();
>        
>      System.err.println("locked OK");
>      String javaCmd = System.getProperty("java.home") + 
>                         File.separator +
> 			"bin" + 
> 			File.separator + 
> 			"java";
>     if(args.length == 0) {
>             Process p = Runtime.getRuntime().exec(new String[] { javaCmd, 
>             "-cp",
>             System.getProperty("java.class.path"),
>             "Test", "foo" } );
>       
>             String line;
>             InputStream is = p.getInputStream();
>             BufferedReader input = new BufferedReader(new InputStreamReader(p
>                     .getErrorStream()));
>             while ((line = input.readLine()) != null) {
>                 System.err.println("Child prints: " + line);
>             }
>            input.close();
>     }
>   }
> }
> Steps to reproduce:
> 1. Build Harmony j2se subset as described in README.txt. 
> 2. Compile Test.java using BEA 1.4 javac 
> > javac Test.java 
> 3. Run java using compatible VM (J9) 
> > java Test
> Output :
> java version "1.4.2_04"
> Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_04-b05)
> BEA WebLogic JRockit(TM) 1.4.2_04 JVM  (build ari-31788-20040616-1132-win-ia32,
> Native Threads, GC strategy: parallel)
> locked OK
> Child prints: locked OK
> Output in Harmony:
> locked OK
> <here test hangs>
> JUnit test:
> ---------------FileLockTest.java------------
> import java.io.*;
> import junit.framework.*;
> public class FileLockTest extends TestCase {
> 	static boolean childVM = false;
> 	public static void main(String[] args) {
> 		childVM = args.length > 0;
> 		junit.textui.TestRunner.run(FileLockTest.class);
> 	}
> 	public void testFileLock() throws Exception {
> 		File f = new File("abcd");
>                                            f.deleteOnExit();
> 		new FileOutputStream(f, true).getChannel().tryLock();
> 		System.err.println("locked OK");
> 		String javaCmd = System.getProperty("java.home") + File.separator
> 				+ "bin" + File.separator + "java";
> 		if (!childVM) {
> 			Process p = Runtime.getRuntime().exec(
> 					new String[] { javaCmd, "-cp",
> 							System.getProperty("java.class.path"),
> 							this.getClass().getName(), "foo" });
> 			String line;
> 			BufferedReader input = new BufferedReader(new InputStreamReader(p
> 					.getErrorStream()));
> 			while ((line = input.readLine()) != null) {
> 				System.err.println("Child prints: " + line);
> 			}
> 			input.close();
> 		}
> 	}
> }

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