You are right, but only for the lock manager. The lock manager takes
care of uniquely mapping a resource id to a lock, but when you work on
a lock *directly* it must - of course - be the same object.
Oliver
On 7/6/05, Aaron Hamid <[EMAIL PROTECTED]> wrote:
> Is this true? It was my impression, have first written such a class, and
> then finding and skimming the javadoc for [ReadWrite]LockManager, and
> particularly 'getLock' and 'createLock', that lock singletons would be
> automatically created and managed. Otherwise the developer must write a lot
> of boilerplate code for keeping a singleton map of locks. Surely only the
> 'resourceId' must be the same, and not the actual ReadWriteLock reference?
>
> LockManager: "Encapsulates creation, removal, and retrieval of locks. Each
> resource can have at most a single lock."
>
> Aaron
>
> Oliver Zeigermann wrote:
> > Ooops, sorry, you are right. Not only the resource Id, but the lock
> > *itself* must be the same in both threads.
> >
> > Doing it this way:
> >
> > final ReadWriteLock fileLock = new ReadWriteLock("Huhu",
> > loggerFacade);
> > Runnable run = new Runnable() {
> >
> > public void run() {
> >
> > try {
> > System.out.println("before acquiring
> > a lock "
> > +
> > Thread.currentThread());
> > boolean result =
> > fileLock.acquireWrite(Thread
> > .currentThread(),
> > Long.MAX_VALUE);
> > System.out.println("lock result: " +
> > result + " "
> > +
> > Thread.currentThread());
> > Thread.sleep(20000);
> > System.out.println("after sleeping "
> > +
> > Thread.currentThread());
> > } catch (InterruptedException e) {
> > e.printStackTrace(System.err);
> >
> > } finally {
> >
> > fileLock.release(Thread.currentThread());
> > }
> > }
> >
> > };
> >
> > Thread t1 = new Thread(run, "Thread1");
> > Thread t2 = new Thread(run, "Thread2");
> > t1.start();
> > try {
> > Thread.sleep(1000);
> > } catch (InterruptedException e) {
> > }
> > t2.start();
> >
> >
> > works fine for me.
> >
> > HTH
> >
> > Oliver
> >
> > On 7/6/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> >
> >>
> >>
> >>
> >>
> >>Oliver,
> >>
> >>I tried your suggestion by changing my ReadWriteLock statement to
> >>
> >>ReadWriteLock fileLock = new ReadWriteLock("c:/logRec.txt",loggerFacade);
> >>
> >>However, I received the same results as when I used new File(..).
> >>
> >>LeRoy
> >>
> >>
> >>
> >>
> >>
> >>
> >> Oliver Zeigermann
> >> <oliver.zeigerman
> >> [EMAIL PROTECTED]>
> >> To
> >> Jakarta Commons Users List
> >> 07/06/2005 01:44 <[email protected]>
> >> AM cc
> >>
> >> Subject
> >> Please respond to Re: Transaction API, ReadWriteLock
> >> "Jakarta Commons
> >> Users List"
> >> <[EMAIL PROTECTED]
> >> arta.apache.org>
> >>
> >>
> >>
> >>
> >>
> >>
> >>Most likely your problem ist that new File(..) creates different
> >>objects in each thread. I would try using something like the path to
> >>the file as String.
> >>
> >>Oliver
> >>
> >>On 7/5/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> >>
> >>>
> >>>
> >>>
> >>>I'm trying to use the ReadWriteLock class to acquire a write lock on a
> >>
> >>file
> >>
> >>>in a servlet. When I generate multiple threads of the servlet using a
> >>
> >>WTE
> >>
> >>>5.1 server in the WSAD 5.1 IDE, I'm not able to get ReadWriteLock to
> >>
> >>block
> >>
> >>>other servlet threads after the first servlet thread obtains the lock.
> >>
> >>I'm
> >>
> >>>using two IE browser windows to generate the two servlet threads. Below
> >>
> >>is
> >>
> >>>ReadWriteLock code I have in the servlet followed by the
> >>
> >>System.out.println
> >>
> >>>statements that are generated in the server log file during my test.
> >>>
> >>>ReadWriteLock fileLock = new ReadWriteLock(new File(c:/logRec.txt,
> >>>loggerFacade);
> >>>try {
> >>> System.out.println("before acquiring a lock " +
> >>>Thread.currentThread());
> >>> boolean result =
> >>>fileLock.acquireWrite(Thread.currentThread(),Long.MAX_VALUE);
> >>> System.out.println("lock result: " + result + " " +
> >>>Thread.currentThread());
> >>> Thread.sleep(20000);
> >>> System.out.println("after sleeping " + Thread.currentThread());
> >>> FileWriter recFile = new FileWriter(c:/logRec.txt, true);
> >>> recFile.write("text from testFileTran");
> >>> recFile.close();
> >>>} catch (InterruptedException e) {
> >>> e.printStackTrace(System.err);
> >>>
> >>>} catch (IOException e) {
> >>> e.printStackTrace(System.err);
> >>>
> >>>} finally {
> >>> fileLock.release(Thread.currentThread());
> >>>}
> >>>
> >>>[7/5/05 8:26:03:326 CDT] 7c1477e SystemOut O before acquiring a lock
> >>>Thread[Servlet.Engine.Transports : 0,5,main]
> >>>[7/5/05 8:26:03:326 CDT] 7c1477e SystemOut O lock result: true
> >>>Thread[Servlet.Engine.Transports : 0,5,main]
> >>>[7/5/05 8:26:08:384 CDT] 24c3477d SystemOut O before acquiring a lock
> >>>Thread[Servlet.Engine.Transports : 1,5,main]
> >>>[7/5/05 8:26:08:384 CDT] 24c3477d SystemOut O lock result: true
> >>>Thread[Servlet.Engine.Transports : 1,5,main]
> >>>[7/5/05 8:26:23:335 CDT] 7c1477e SystemOut O after sleeping
> >>>Thread[Servlet.Engine.Transports : 0,5,main]
> >>>[7/5/05 8:26:28:382 CDT] 24c3477d SystemOut O after sleeping
> >>>Thread[Servlet.Engine.Transports : 1,5,main]
> >>>
> >>>
> >>>From reviewing the Transaction documentation and mailing list archives,
> >>
> >>I'm
> >>
> >>>not able to determine what I'm doing wrong.
> >>>
> >>>
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> >>>
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> >>
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> >>
> >
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