[FLINK-987] Extend TypeSerializers and -Comparators to work directly on Memory Segments

• Type: Improvement
• Status: Open
• Priority: Not a Priority
• Resolution: Unresolved
• Affects Version/s: 0.6-incubating
• Component/s: Runtime / Task
• Labels: auto-deprioritized-major auto-deprioritized-minor
• Assignee: Unassigned
• Reporter: Stephan Ewen
• Created: 26/Jun/14 14:57
• Updated: 10/Feb/22 22:36

Description

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:

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);