tree de90f6bce4ec182a4059f752fd14e4a26e055e23
parent 7c62e1232cf8063d3b0f0dc59978da69710602b5
author mtang01 <49574764+mtang01@users.noreply.github.com> 1556591464 -0700
committer Sijie Guo <guosijie@gmail.com> 1556591464 +0800

ISSUE #2067: reduce byte[] allocation in add entry

Descriptions of the changes in this PR:
This change removes a byte[] copy in DigestManager digest calculation
(computeDigestAndPackageForSending)
that puts crc header and payload in a continuous buffer. Instead,
it uses protobuf ByteString.concat to concatenate header and payload
without copy when building protobuf message.


### Motivation

In add entry code path, I see lots of byte[] allocated to do digest calculation.  It's possible to not allocate byte[]. 

### Changes

Don't allocate a ByteBuf to copy data. Keep header and data separate, but use ByteString.concat when construct protobuf message.

Master Issue: #2067 


Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <sijie@apache.org>

This closes #2068 from mtang01/add_entry_mem, closes #2067