encoding/json: prevent duplicate slicebytetostring

When storing literal to JSON number v, if s is valid number, the slicebytetostring operation will be performed twice. In fact, the operation is unavoidable on any code path, so just perform it at the very beginning.

This is not a big optimization, but better than nothing:

    $ ../bin/go test ./encoding/json/ -bench UnmarshalNumber -run NOTEST -benchtime 10000000x -count 16  > old.txt
    $ ../bin/go test ./encoding/json/ -bench UnmarshalNumber -run NOTEST -benchtime 10000000x -count 16  > new.txt
    $ benchstat old.txt new.txt
                      │   old.txt   │              new.txt               │
                      │   sec/op    │   sec/op     vs base               │
    UnmarshalNumber-8   234.5n ± 3%   228.2n ± 4%  -2.67% (p=0.033 n=16)

                      │  old.txt   │            new.txt             │
                      │    B/op    │    B/op     vs base            │
    UnmarshalNumber-8   168.0 ± 0%   168.0 ± 0%  ~ (p=1.000 n=16) ¹
    ¹ all samples are equal

                      │  old.txt   │            new.txt             │
                      │ allocs/op  │ allocs/op   vs base            │
    UnmarshalNumber-8   2.000 ± 0%   2.000 ± 0%  ~ (p=1.000 n=16) ¹
    ¹ all samples are equal

Change-Id: I1dfdb1ed0883e385f753b2046b7f047c792aa4e3
GitHub-Last-Rev: d236dd7265f110dbb6e0b9b0a824aab9ba7c36be
GitHub-Pull-Request: golang/go#61242
Reviewed-on: https://go-review.googlesource.com/c/go/+/508556
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: qiulaidongfeng <2645477756@qq.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
2 files changed
tree: c1c27e2f2d36a40dccaf93f00912a059e7151b36
  1. .github/
  2. api/
  3. doc/
  4. lib/
  5. misc/
  6. src/
  7. test/
  8. .gitattributes
  9. .gitignore
  10. codereview.cfg
  11. CONTRIBUTING.md
  12. go.env
  13. LICENSE
  14. PATENTS
  15. README.md
  16. SECURITY.md
README.md

The Go Programming Language

Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.

Gopher image Gopher image by Renee French, licensed under Creative Commons 4.0 Attributions license.

Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.

Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.

Download and Install

Binary Distributions

Official binary distributions are available at https://go.dev/dl/.

After downloading a binary release, visit https://go.dev/doc/install for installation instructions.

Install From Source

If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.

Contributing

Go is the work of thousands of contributors. We appreciate your help!

To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.

Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.