I'm aware of the reasons behind this issue. However, I'm still unsure
whether this is a safe enough solution. A user could obtain an instance
of a Clipboard object by using its public constructor. They could also
get it using Clipboard.getSystemClipboard(), and the latter could call
the methods that you're changing from a non-EDT thread (directly or
indirectly). In any case, the fix that you're proposing changes the
threading contract for these methods considerably. And I don't think
that this change is safe.
--
best regards,
Anthony
On 4/7/2014 5:52 PM, Petr Pchelko wrote:
Clipboard is a part of AWT API. The AWT is a multi-threaded GUI toolkit, which
means that users can call Clipboard's methods on
any thread. If we remove invokeLater(), we break this contract, which I'm not
sure we want to do.
The FlavorListener and ClipboardOwner interfaces do not state that the
callbacks would be called on EDT, so at least we are not breaking the spec.
The problem here is that Clipboard would be a part of a different module and
must be independent from AWT or the desktop module. Even reflectively
independent.
This means we have 2 options here: option 1 is implemented in the fix.
Option 2 is to declare some "DelayedNotificationService", make the Clipboard
look for this service using a ServiceLoader and make AWT implement the service
using the invokeLater. So if the Clipboard would be used in absence of desktop
module it would deliver the notifications in place, and with the desktop module
it will
use the invokeLater. Personally I think that the second option is way more
fragile and unnecessary complicated.
The only place where the Clipboard is used directly is in swing's sandbox
clipboard, but it's used internally and only on EDT. And it does not leak to
the user.
So if we just remove the invokeLater we would likely not break anything. With
the second option I would not be so sure.
With best regards. Petr.
On 07.04.2014, at 17:42, Anthony Petrov <[email protected]> wrote:
Hi Petr,
Clipboard is a part of AWT API. The AWT is a multi-threaded GUI toolkit, which
means that users can call Clipboard's methods on any thread. If we remove
invokeLater(), we break this contract, which I'm not sure we want to do.
--
best regards,
Anthony
On 4/7/2014 5:16 PM, Petr Pchelko wrote:
Hello, AWT Team.
Please review the fix for the issue:
https://bugs.openjdk.java.net/browse/JDK-8039377
The fix is here:
http://cr.openjdk.java.net/~pchelko/9/8039377/webrev.00/
The problem: Clipboard depend on the EventQueue. The solution - remove the
invokeLater. The Clipboard object is used only as a Swing sandbox clipboard
which is used from the EDT.
The user can't use in as the System clipboard, so there's no worries about the
callback being executed on some privileged thread. So we can simply remove the
invokeLater here.
With best regards. Petr.
