RFC: Netx - Implement SingeInstanceService
omajid at redhat.com
Tue Jun 23 07:27:58 PDT 2009
Updated patch attached.
Andrew Haley wrote:
> Omair Majid wrote:
>> Andrew Haley wrote:
>>> Omair Majid wrote:
>>>> The attached patch adds support for SingleInstanceService to Netx.
>>>> It creates a lock file under ~/.netx/locks/ once an application adds a
>>>> SingleInstanceListener to the SingleInstanceService. A second instance
>>>> of the application sees this lock file, sends it's arguments to the
>>>> first instance and shuts down.
>>> Do you know that the first instance is connected to the same X server?
>> Just to be clear, even though the file names begin with X, they dont
>> have much to do with the X server. All Linux implementations of jnlp
>> services are prefixed with X in Netx.
>> To answer the question: no. This patch enforces a single instance per
>> user rather than per X session. Many other applications (such as
>> Firefox) do the same thing.
> I am aware of that, of course: it's a famous longstanding Firefox bug.
> What I don't know is whether jnlp is supposed to behave the same way;
> I can't tell from the javadoc. If it really is supposed to do that, fine.
The updated patch enforces a single instance per X session.
>>> What happens if a stale lock file is left behind by some earlier event?
>> This patch never cleans up the lock files. Each lock file contains a
>> port number where first instance of the application is listening. If no
>> application is listening at the port, then the file is assumed to be
>> stale and ignored/overwritten.
> Sounds good.
>>> Is it good to use NFS for the lock file? Would something in /tmp work
>> Honestly, I have no clue. Fwiw, Sun's JRE creates lock files under
>> ~/.java/ . I have no issues with using /tmp if you think that would work
> It probably is better, yes.
Done. Netx now puts locks under /tmp/$USER/netx/locks.
2009-06-23 Omair Majid <omajid at redhat.com>
(launchApplication): Check for any existing single instance.
Dont start a second instance.
Added USER, TMP_DIR, and changed LOCKS_DIR
(getSingleInstanceService): New function.
(checkExistingSingleInstance): New function.
SingleInstanceService to serviceNames. Create a new instance of
XSingleInstanceService as a privileged proxy.
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