[jdk16] Integrated: 8259027: NullPointerException in makeMappedSegment due to NULL Unmapper when length of segment is 0

[Maurizio Cimadamore]

On Tue, 5 Jan 2021 12:56:49 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> When the size of the memory map is zero, FileChannelImpl returns a `null` Unmapper - this creates issues to the mapped memory segment implementation.
> 
> To fix, I've created an empty mapped segment class which is initialized to sensible defaults, and whose implenentation of force/load etc. do nothing.
> 
> We already had a test for this condition - but the test was missing the `@Test` annotation, so it was not run! I've now beefed up the test a bit to make sure that mapped segment operations do not throw.

This pull request has now been integrated.

Changeset: b7940aa1
Author:    Maurizio Cimadamore <mcimadamore at openjdk.org>
URL:       https://git.openjdk.java.net/jdk16/commit/b7940aa1
Stats:     54 lines in 2 files changed: 51 ins; 1 del; 2 mod

8259027: NullPointerException in makeMappedSegment due to NULL Unmapper when length of segment is 0

Reviewed-by: chegar, uschindler

-------------

PR: https://git.openjdk.java.net/jdk16/pull/83