Keploy fork of gopkg.in/yaml.v3

This fork exists for one bug fix. It is gopkg.in/yaml.v3 v3.0.1 (the archived go-yaml/yaml, branch v3) plus commit 4d4399b, which reuses the emitter's event queue once it drains. Nothing else differs, and the encoder writes the same bytes as v3.0.1.

The bug. yaml_emitter_emit never reuses the queue slots of events it has already written. The queue grows by one slot per event for the life of the emitter:

• Every Marshal or Encoder.Encode allocates memory in proportion to the number of events in the document.
• A long-lived Encoder keeps growing across documents.

The effect on Keploy. On a recorded 27.4 KB mock:

	CPU	allocated	GC share of CPU
v3.0.1	0.89 to 0.91 ms	1,491 KB	31%
this fork	0.51 to 0.55 ms	63.5 KB	3 to 4%

The output was byte-identical (the same sha256) across 146,862 real mocks.

Upstream. The fix is proposed to the maintained successor, go.yaml.in/yaml, in yaml/go-yaml#432. Drop this fork once the fix ships in a module Keploy can use.

Using it

The module path stays gopkg.in/yaml.v3, so use the fork through a replace directive, and keep the require gopkg.in/yaml.v3 v3.0.1 line as it is:

replace gopkg.in/yaml.v3 => github.com/keploy/yaml v0.0.0-20260930140430-4d4399ba5dc4

• Put it in each binary's go.mod. Replace directives apply only in the main module, so a replace in a library's go.mod does not reach the programs that import it.
• Keep the fix commit reachable. v3-keploy, the default branch, holds it. Do not rewrite or delete the branch, or builds with GOPROXY=direct can no longer fetch the pinned commit.

---

THIS PROJECT IS UNMAINTAINED

This was one of my first Go projects, bootstapped over the christmas break of 2010 and well maintained for over a decade, often with help from contributors. Sadly, in the last few years my own free time, both personal and professional, became less common, and none of the contributions turned into more extensive long term engagements. I was hoping to address the situation by moving it into a dedicated professional team at a more resourceful home such as Canonical, Google, etc, but that hasn't materialized in time either. So I'm now taking the more explicit action of clearly labeling the project as unmaintained, to inform the community of what should already be obvious by now.

There's still a chance I may come back and bring this project to where I wish it should go, but something else will have to change for this to be viable. Unfortunately, despite my own lack of time for the project, I cannot just "hand off" maintenance to an individual or to a small group either, due to the likelyhood of the project going back into an unmaintained, unstable, or even abused state.

Sorry about that.

-- Gustavo Niemeyer

ORIGINAL README

YAML support for the Go language

Introduction

The yaml package enables Go programs to comfortably encode and decode YAML values. It was developed within Canonical as part of the juju project, and is based on a pure Go port of the well-known libyaml C library to parse and generate YAML data quickly and reliably.

Compatibility

The yaml package supports most of YAML 1.2, but preserves some behavior from 1.1 for backwards compatibility.

Specifically, as of v3 of the yaml package:

• YAML 1.1 bools (yes/no, on/off) are supported as long as they are being decoded into a typed bool value. Otherwise they behave as a string. Booleans in YAML 1.2 are true/false only.
• Octals encode and decode as 0777 per YAML 1.1, rather than 0o777 as specified in YAML 1.2, because most parsers still use the old format. Octals in the 0o777 format are supported though, so new files work.
• Does not support base-60 floats. These are gone from YAML 1.2, and were actually never supported by this package as it's clearly a poor choice.

and offers backwards compatibility with YAML 1.1 in some cases. 1.2, including support for anchors, tags, map merging, etc. Multi-document unmarshalling is not yet implemented, and base-60 floats from YAML 1.1 are purposefully not supported since they're a poor design and are gone in YAML 1.2.

Installation and usage

The import path for the package is gopkg.in/yaml.v3.

To install it, run:

go get gopkg.in/yaml.v3

API documentation

If opened in a browser, the import path itself leads to the API documentation:

• https://gopkg.in/yaml.v3

API stability

The package API for yaml v3 will remain stable as described in gopkg.in.

License

The yaml package is licensed under the MIT and Apache License 2.0 licenses. Please see the LICENSE file for details.

Example

package main

import (
        "fmt"
        "log"

        "gopkg.in/yaml.v3"
)

var data = `
a: Easy!
b:
  c: 2
  d: [3, 4]
`

// Note: struct fields must be public in order for unmarshal to
// correctly populate the data.
type T struct {
        A string
        B struct {
                RenamedC int   `yaml:"c"`
                D        []int `yaml:",flow"`
        }
}

func main() {
        t := T{}
    
        err := yaml.Unmarshal([]byte(data), &t)
        if err != nil {
                log.Fatalf("error: %v", err)
        }
        fmt.Printf("--- t:\n%v\n\n", t)
    
        d, err := yaml.Marshal(&t)
        if err != nil {
                log.Fatalf("error: %v", err)
        }
        fmt.Printf("--- t dump:\n%s\n\n", string(d))
    
        m := make(map[interface{}]interface{})
    
        err = yaml.Unmarshal([]byte(data), &m)
        if err != nil {
                log.Fatalf("error: %v", err)
        }
        fmt.Printf("--- m:\n%v\n\n", m)
    
        d, err = yaml.Marshal(&m)
        if err != nil {
                log.Fatalf("error: %v", err)
        }
        fmt.Printf("--- m dump:\n%s\n\n", string(d))
}

This example will generate the following output:

--- t:
{Easy! {2 [3 4]}}

--- t dump:
a: Easy!
b:
  c: 2
  d: [3, 4]


--- m:
map[a:Easy! b:map[c:2 d:[3 4]]]

--- m dump:
a: Easy!
b:
  c: 2
  d:
  - 3
  - 4