commit c37adefdac3634ee9b6f9494ff75001b93d01c28
author Damien Neil <dneil@google.com> Mon Apr 01 13:49:56 2019 -0700
committer Damien Neil <dneil@google.com> Thu May 16 22:13:43 2019 +0000
tree c33826c923260266ebbb9ea383ff1e9e896da250
parent 5c62f675c54b8781b00a44070ed6f6a5d55fa4a6

internal/impl: add fast-path marshal implementation

This is a port of the v1 table marshaler, with some substantial
cleanup and refactoring.

Benchstat results from the protobuf reference benchmark data comparing the
v1 package with v2, with AllowPartial:true set for the new package. This
is not an apples-to-apples comparison, since v1 doesn't have a way to
disable required field checks.  Required field checks in v2 package
currently go through reflection, which performs terribly; my initial
experimentation indicates that fast-path required field checks will
not add a large amount of cost; these results are incomplete but not
wholly inaccurate.

name                                           old time/op  new time/op  delta
/dataset.google_message3_1.pb/Marshal-12        219ms ± 1%   232ms ± 1%   +5.85%  (p=0.004 n=6+5)
/dataset.google_message2.pb/Marshal-12          261µs ± 3%   248µs ± 1%   -5.14%  (p=0.002 n=6+6)
/dataset.google_message1_proto2.pb/Marshal-12   681ns ± 2%   637ns ± 3%   -6.53%  (p=0.002 n=6+6)
/dataset.google_message1_proto3.pb/Marshal-12  1.10µs ± 8%  0.99µs ± 3%   -9.63%  (p=0.002 n=6+6)
/dataset.google_message3_3.pb/Marshal-12       44.2ms ± 3%  35.2ms ± 1%  -20.28%  (p=0.004 n=6+5)
/dataset.google_message4.pb/Marshal-12         91.4ms ± 2%  94.9ms ± 2%   +3.78%  (p=0.002 n=6+6)
/dataset.google_message3_2.pb/Marshal-12       78.7ms ± 6%  80.8ms ± 4%     ~     (p=0.310 n=6+6)
/dataset.google_message3_4.pb/Marshal-12       10.6ms ± 3%  10.6ms ± 8%     ~     (p=0.662 n=5+6)
/dataset.google_message3_5.pb/Marshal-12        675ms ± 4%   510ms ± 2%  -24.40%  (p=0.002 n=6+6)
/dataset.google_message3_1.pb/Marshal           219ms ± 1%   236ms ± 7%   +8.06%  (p=0.004 n=5+6)
/dataset.google_message2.pb/Marshal             257µs ± 1%   250µs ± 3%     ~     (p=0.052 n=5+6)
/dataset.google_message1_proto2.pb/Marshal      685ns ± 1%   628ns ± 1%   -8.41%  (p=0.008 n=5+5)
/dataset.google_message1_proto3.pb/Marshal     1.08µs ± 1%  0.98µs ± 2%   -9.31%  (p=0.004 n=5+6)
/dataset.google_message3_3.pb/Marshal          43.7ms ± 1%  35.1ms ± 1%  -19.76%  (p=0.002 n=6+6)
/dataset.google_message4.pb/Marshal            93.4ms ± 4%  94.9ms ± 2%     ~     (p=0.180 n=6+6)
/dataset.google_message3_2.pb/Marshal           105ms ± 2%    98ms ± 7%   -6.81%  (p=0.009 n=5+6)
/dataset.google_message3_4.pb/Marshal          16.3ms ± 6%  15.7ms ± 3%   -3.44%  (p=0.041 n=6+6)
/dataset.google_message3_5.pb/Marshal           676ms ± 4%   504ms ± 2%  -25.50%  (p=0.004 n=6+5)

Change-Id: I72cc4597117f4cf5d236ef505777d49dd4a5f75d
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/171020
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>