RFR: 8262725: IGV: crash when removing all graphs in a group

[Christian Hagedorn]

On Fri, 16 Apr 2021 09:11:30 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> This change makes IGV close graph views when their groups are either a) removed or b) emptied (all graphs are removed but the group remains), and avoids faulty graph view computation in case b).
> 
> Tested the following scenarios manually (on groups loaded both via network and from a file, and on JDK 8, 11, and 15):
> 1. open a graph, then remove all graphs in the group (as described in the [bug report](https://bugs.openjdk.java.net/browse/JDK-8262725));
> 2. open a graph, then remove its group; and
> 3. open a graph, then remove all graphs and groups (File -> Remove all graphs and groups).

Looks good!

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java line 236:

> 234:                     closeOnRemovedOrEmptyGroup();
> 235:                 }
> 236:             });

Can be replace with `.addListener(g -> closeOnRemovedOrEmptyGroup())`. Same for below.

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Marked as reviewed by chagedorn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/3540