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https://issues.apache.org/jira/browse/FLINK-987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14054692#comment-14054692
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Aljoscha Krettek commented on FLINK-987:
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Yes I know it's performance critical, that's why I'm hesitant to add stuff
there and thinking carefully about how it should be done.
The reason for the locking is that it enables serializers to use relative
positions when seeking and telling and also because you need to know when
underlying buffers can be sent away when writing spanning records: You start
writing in one buffer, underneath we switch to the next buffer (here we send
the old buffer off right now), but we have to keep the old buffer in case the
serializer needs to write a header or some such thing into the starting buffer.
> Extend TypeSerializers and -Comparators to work directly on Memory Segments
> ---------------------------------------------------------------------------
>
> Key: FLINK-987
> URL: https://issues.apache.org/jira/browse/FLINK-987
> Project: Flink
> Issue Type: Improvement
> Components: Local Runtime
> Affects Versions: 0.6-incubating
> Reporter: Stephan Ewen
> Assignee: Aljoscha Krettek
> Fix For: 0.6-incubating
>
>
> As per discussion with [~till.rohrmann], [~uce], [~aljoscha], we suggest to
> change the way that the TypeSerialzers/Comparators and
> DataInputViews/DataOutputViews work.
> The goal is to allow more flexibility in the construction on the binary
> representation of data types, and to allow partial deserialization of
> individual fields. Both is currently prohibited by the fact that the
> abstraction of the memory (into which the data goes) is a stream abstraction
> ({{DataInputView}}, {{DataOutputView}}).
> An idea is to offer a random-access buffer like view for construction and
> random-access deserialization, as well as various methods to copy elements in
> a binary fashion between such buffers and streams.
> A possible set of methods for the {{TypeSerializer}} could be:
> {code}
> long serialize(T record, TargetBuffer buffer);
>
> T deserialize(T reuse, SourceBuffer source);
>
> void ensureBufferSufficientlyFilled(SourceBuffer source);
>
> <X> X deserializeField(X reuse, int logicalPos, SourceBuffer buffer);
>
> int getOffsetForField(int logicalPos, int offset, SourceBuffer buffer);
>
> void copy(DataInputView in, TargetBuffer buffer);
>
> void copy(SourceBuffer buffer,, DataOutputView out);
>
> void copy(DataInputView source, DataOutputView target);
> {code}
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