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https://issues.apache.org/jira/browse/FLINK-11775?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16815158#comment-16815158
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Stephan Ewen commented on FLINK-11775:
--------------------------------------
I think that having {{AbstractPagedOutputView implements DataOutputView,
MemorySegmentWritable}} can work.
Can you share how you plan to implement this? Will the implementation of the
write method cast the memory segment to a specific type (like
{{HybridMemorySegment}}) and then make an unsafe copy?
There should still be a generic fallback path that works for all memory
segments, like going through a temporary array, or wrapping the MemorySegment
as a ByteBuffer and reading data from there into memory structure of the
AbstractPagedOutputView.
> Introduce MemorySegmentWritable to let DataOutputView direct copy to internal
> bytes
> -----------------------------------------------------------------------------------
>
> Key: FLINK-11775
> URL: https://issues.apache.org/jira/browse/FLINK-11775
> Project: Flink
> Issue Type: New Feature
> Components: Runtime / Operators
> Reporter: Jingsong Lee
> Assignee: Jingsong Lee
> Priority: Major
>
> Blink new binary format is based on MemorySegment.
> Introduce MemorySegmentWritable to let DataOutputView direct copy to internal
> bytes
> {code:java}
> /**
> * Provides the interface for write(Segment).
> */
> public interface MemorySegmentWritable {
> /**
> * Writes {@code len} bytes from memory segment {@code segment} starting at
> offset {@code off}, in order,
> * to the output.
> *
> * @param segment memory segment to copy the bytes from.
> * @param off the start offset in the memory segment.
> * @param len The number of bytes to copy.
> * @throws IOException if an I/O error occurs.
> */
> void write(MemorySegment segment, int off, int len) throws IOException;
> }{code}
>
> If we want to write a Memory Segment to DataOutputView, we need to copy bytes
> to byte[] and then write it in, which is less effective.
> If we let AbstractPagedOutputView have a write(MemorySegment) interface, we
> can copy it directly.
> We need to ensure this in network serialization, batch operator calculation
> serialization, Streaming State serialization to avoid new byte[] and copy.
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