Use snappy compression for internal gRPC communication.

[danielmai]

Closes #3358.

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This change is 

[codexnull]

Reviewed 2 of 17 files at r1.
Reviewable status: 2 of 17 files reviewed, all discussions resolved (waiting on @manishrjain)

[martinmr]

Reviewed 16 of 17 files at r1, 1 of 1 files at r2.
Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @danielmai and @manishrjain)

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conn/pool.go, line 153 at r2 (raw file):

			grpc.MaxCallRecvMsgSize(x.GrpcMaxSize),
			grpc.MaxCallSendMsgSize(x.GrpcMaxSize),
			grpc.UseCompressor((snappyCompressor{}).Name())),

You don't need the parentheses

Example: https://play.golang.org/p/T5DzEZhF_x8

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conn/snappy.go, line 1 at r2 (raw file):

// Copyright 2017 The Cockroach Authors.

Is the copyright message right?

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conn/snappy.go, line 25 at r2 (raw file):

)

// NB: The encoding.Compressor implementation needs to be goroutine

nit: what is NB supposed to stand for?

[danielmai]

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @manishrjain and @martinmr)

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conn/pool.go, line 153 at r2 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

You don't need the parentheses

Example: https://play.golang.org/p/T5DzEZhF_x8

Nice catch. But I don't feel that it's necessary to change the source from CockroachDB.

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conn/snappy.go, line 1 at r2 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

Is the copyright message right?

Yes. This file is from CockroachDB: https://github.com/cockroachdb/cockroach/blob/856ba9108f112f85d406bbe88d2208651859336e/pkg/rpc/snappy.go. It's the bare minimum needed to implement a gRPC compressor using snappy compression. Aside from the package name, everything else is the same.

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conn/snappy.go, line 25 at r2 (raw file):

Previously, martinmr (Martin Martinez Rivera) wrote…

nit: what is NB supposed to stand for?

I'm not too sure, but it's probably this: https://en.wikipedia.org/wiki/Nota_bene. Basically, "pay attention". Again, I didn't change it from the original source.

[martinmr]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @manishrjain)

[campoy]

Hey @danielmai, what happened to this PR?

[danielmai]

@campoy This PR in its current state would require all instances to use snappy compression for internal communication. Ideally, it'd be better if instances opted-in to use snappy compression for internal traffic if available to allow for rolling upgrades.

This PR was created on the hunch that there'd be improvements for resource usage or performance with compressed payloads, but there was no investigation to confirm this.

It'd be great if someone else could pick up where I left off here.

[manishrjain]

Reviewed 16 of 17 files at r1, 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved