buffer: optimize decoding wrapped base64 data by aqrln · Pull Request #12146 · nodejs/node · GitHub

The fast base64 decoder used to switch to the slow one permanently when
it saw a whitespace or other garbage character. Since the most common
situation such characters may be encountered in is line-wrapped base64
data, a more profitable strategy is to decode a single 24-bit group with
the slow decoder and then continue running the fast algorithm.

Refs: #12114

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
commit message follows commit guidelines

Affected core subsystem(s)

buffer

I haven't run the whole benchmark suite yet, only symlinked the exiting and the new benchmarks into a new directory locally:

                                             improvement confidence      p.value
 base64/buffer-base64-decode-wrapped.js n=32     11.04 %        *** 4.413651e-27
 base64/buffer-base64-decode.js n=32             -1.49 %            5.613341e-02

CI: https://ci.nodejs.org/job/node-test-pull-request/7140/

minor nit but this can be simplified just a bit by doing...

const line = 'abcd'.repeat(charsPerLine / 4) + '\n';
const buffer = Buffer.alloc(bytesCount, line);

Done. Thanks for the suggestion!

The fast base64 decoder used to switch to the slow one permanently when it saw a whitespace or other garbage character. Since the most common situation such characters may be encountered in is line-wrapped base64 data, a more profitable strategy is to decode a single 24-bit group with the slow decoder and then continue running the fast algorithm. Refs: nodejs#12114

Rebased to incorporate changes from #11995.

Thank you!

Can I get a fresh CI run?

CI: https://ci.nodejs.org/job/node-test-pull-request/7192/

not sure I'm qualified to sign off on this but LGTM

/cc @bnoordhuis (based on Git history)

This LGTM but it would be really nice to have some cctests for this header file

(to be clear, the cctest can be added separately :-) ...)

The fast base64 decoder used to switch to the slow one permanently when it saw a whitespace or other garbage character. Since the most common situation such characters may be encountered in is line-wrapped base64 data, a more profitable strategy is to decode a single 24-bit group with the slow decoder and then continue running the fast algorithm. PR-URL: #12146 Ref: #12114 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

Landed in e77a83f

This commit adds C++ tests for `base64_encode()` and `base64_decode()` functions defined in `base64.h`. The functionality is already being tested indirectly in JavaScript tests for Buffer, but it won't hurt to test the low-level functions too, especially given that they aren't only used in the internal Buffer implementation, Chrome inspector protocol support relies upon them too. Refs: nodejs#12146 (comment)

This commit adds C++ tests for `base64_encode()` and `base64_decode()` functions defined in `base64.h`. The functionality is already being tested indirectly in JavaScript tests for Buffer, but it won't hurt to test the low-level functions too, especially given that they aren't only used in the internal Buffer implementation, Chrome inspector protocol support relies upon them too. PR-URL: #12238 Refs: #12146 (comment) Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Richard Lau <riclau@uk.ibm.com> Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

The fast base64 decoder used to switch to the slow one permanently when it saw a whitespace or other garbage character. Since the most common situation such characters may be encountered in is line-wrapped base64 data, a more profitable strategy is to decode a single 24-bit group with the slow decoder and then continue running the fast algorithm. PR-URL: nodejs#12146 Ref: nodejs#12114 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

should we backport?

Assuming if so we should wait a bit

should we backport?

It seems to be the root cause of #13657, so no.

This commit adds C++ tests for `base64_encode()` and `base64_decode()` functions defined in `base64.h`. The functionality is already being tested indirectly in JavaScript tests for Buffer, but it won't hurt to test the low-level functions too, especially given that they aren't only used in the internal Buffer implementation, Chrome inspector protocol support relies upon them too. PR-URL: #12238 Refs: #12146 (comment) Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Richard Lau <riclau@uk.ibm.com> Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>

nodejs-github-bot added buffer Issues and PRs related to the buffer subsystem. c++ Issues and PRs that require attention from people who are familiar with C++. labels Mar 31, 2017

This was referenced Mar 31, 2017

src: use const parameters in base64_decode_slow() #12144

Closed

base64 decoder could be 2x faster when decoding wrapped base64 #12114

Closed

jasnell requested review from addaleax and trevnorris March 31, 2017 15:39

jasnell reviewed Mar 31, 2017

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aqrln force-pushed the base64-optimization branch from 1fb578c to ff77c72 Compare March 31, 2017 20:27

addaleax approved these changes Mar 31, 2017

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trevnorris approved these changes Apr 4, 2017

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jasnell approved these changes Apr 4, 2017

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jasnell closed this Apr 4, 2017

aqrln deleted the base64-optimization branch April 4, 2017 16:46

jasnell mentioned this pull request Apr 4, 2017

8.0.0 Release Proposal #12220

Closed

aqrln mentioned this pull request Apr 5, 2017

test: add basic cctest for base64.h #12238

Closed

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italoacasas mentioned this pull request Apr 10, 2017

v7.9.0 Release Proposal #12319

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MylesBorins added the lts-watch-v6.x label Apr 18, 2017

MylesBorins added the baking-for-lts PRs that need to wait before landing in a LTS release. label May 15, 2017

addaleax added dont-land-on-v4.x and removed baking-for-lts PRs that need to wait before landing in a LTS release. lts-watch-v6.x labels Jun 13, 2017

aqrln mentioned this pull request Jul 21, 2017

src: fix decoding base64 with whitespace #13660

Merged

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buffer: optimize decoding wrapped base64 data by aqrln · Pull Request #12146 · nodejs/node · GitHub

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buffer: optimize decoding wrapped base64 data#12146
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