Bug 578709 - Multiple editor selection dialogs apppear on debugging

Serialized SourceLookup and SourceDisplay jobs.

All source lookups tasks are now put in the queue and handled by a
single job (not multiple jobs running in parallel). Once lookup is done,
the result is passed to the second job dedicated to show lookup results
in the UI. Both jobs ignore duplicated tasks.

As a result, if previously there was possible to run multiple source
lookups in parallel (that would compute same result) and all those
lookup results were shown one after each other in the UI (re-triggering
same UI actions again and again), now all source lookups are executed
one by one and there are no attempts made to show identical lookup
results again.

Change-Id: I1737910e4269e6795d6da1fd71bad1874cc59f7d
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.debug/+/190843
Reviewed-by: Simeon Andreev <simeon.danailov.andreev@gmail.com>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>
Tested-by: Andrey Loskutov <loskutov@gmx.de>
3 files changed