RFR: 8316660: Use a MemorSegment for file mapping in FileChannelLinesSpliterator

[Chen Liang]

On Tue, 19 Sep 2023 08:52:29 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes using a `MemorySegment` instead of a `ByteBuffer` in `FileChannelLinesSpliterator`.
> 
> The old solution deterministically unmapped the ByteBuffer if closed. If not closed, the ByteBuffer would be GC:ed.
> 
> This proposal mimics the old behavior but may hold the mapped memory region slightly longer.
> 
> Tested and passed tier1, tier2, tier3

src/java.base/share/classes/java/nio/file/FileChannelLinesSpliterator.java line 199:

> 197:     }
> 198: 
> 199:     private MemorySegment getMappedByteBuffer() {

This method's name should be updated now that the return type has changed.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15814#discussion_r1329839027