Refine blob cache related code #309
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Signed-off-by: Connor1996 <[email protected]>
Signed-off-by: Connor1996 <[email protected]>
| @@ -725,10 +724,6 @@ Status TitanDBImpl::GetImpl(const ReadOptions& options, | |||
| options.snapshot->GetSequenceNumber(), | |||
| s.ToString().c_str()); | |||
| } | |||
| if (s.ok()) { | |||
| value->Reset(); | |||
| value->PinSelf(record.value); | |||
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Here introduces one memory copy
| } else { | ||
| buffer->PinSlice(blob, OwnedSlice::CleanupFunc, blob.release(), nullptr); | ||
| value->PinSlice(record->value, OwnedSlice::CleanupFunc, blob.release(), |
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So the new logic will return the value only and the old code returns the whole kv value pair?
If that, should the caller of Get() be aware of this change?
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This does not feel right. BlobRecord::DecodeFrom() assumes the buffer contains both key and value. While, I guess this PR wants to optimize the cache utilization by storing value only. In addition to changing the PR description and func comment, we also need to change the decoding logic of BlobRecord accordingly.
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So the new logic will return the value only and the old code returns the whole kv value pair?
Old code reads the kv value pair by record field. New logic still can read the kv value pair by record field. The record is just a slice refering to the pinnable slice underlying buffer. The value pinnable slice holds the underlying buffer, while as a slice I let it only read out value from it instead of the whole buffer.
Should the caller of Get() be aware of this change?
Previously, caller wouldn't use the buffer slice directly as they don't know the content. Key and value are read by record field. So no need to change and I just change the naming buffer to value
We also need to change the decoding logic of BlobRecord accordingly.
No need. When calling BlobRecord::DecodeFrom(), the buffer doesn't contain both key and value.
Signed-off-by: Connor1996 <[email protected]>
This PR does:
Get