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 <[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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> >>>>>For additional commands, e-mail: [EMAIL PROTECTED]
> >>>>>
> >>>>>
> >>>>
> >>>>
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> >>>>
> >>>
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> >>>
> >>>
> >>
> >
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