Yes, all participating threads would need to access the same
transaction manager.
Oliver
On 7/6/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
>
>
>
>
> Switching to use a manager to manage lock references eliminates the need to
> mange lock references, but doesn't this just push this reference problem to
> the manager object?
>
> If classes foo1 and foo2 needed to write to the same file, they would need
> to reference the same manager object to be aware of the lock that was
> created by the other class. If so, then the creation of the manager object
> would need to be placed in Singleton object so both classes could obtain
> the same reference to the manager object. Correct?
>
> LeRoy
>
>
>
>
>
>
> Oliver Zeigermann
> <oliver.zeigerman
> [EMAIL PROTECTED]>
> To
> Jakarta Commons Users List
> 07/06/2005 09:47 <commons-user@jakarta.apache.org>
> AM cc
>
> Subject
> Please respond to Re: Transaction API, ReadWriteLock
> "Jakarta Commons
> Users List"
> <[EMAIL PROTECTED]
> arta.apache.org>
>
>
>
>
>
>
> Exactly. In most cases I would recommend to use a manager.
>
> Oliver
>
> On 7/6/05, Aaron Hamid <[EMAIL PROTECTED]> wrote:
> > I see, so if I do not wish to manage the lock references myself, I (and
> LeRoy also) should always obtain locks through a LockManager.
> >
> > Aaron
> >
> > Oliver Zeigermann wrote:
> > > By the way, when giving me first advice I stumbled over exactly this
> > > difference between the lock manager and the lock itself...
> > >
> > > Oliver
> > >
> > > On 7/6/05, Oliver Zeigermann <[EMAIL PROTECTED]> wrote:
> > >
> > >>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
> <commons-user@jakarta.apache.org>
> > >>>>> 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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> > >>>
> > >>>---------------------------------------------------------------------
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> > >>>
> > >>
> > >
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