github.com/peterbourgon/diskv/v3 v3.0.1: Diskv

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify github.com/peterbourgon/diskv/v3.Diskv in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1
Demonstrate these symbols/APIs:
  - github.com/peterbourgon/diskv/v3.Diskv

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:8deadda58c320bc0969ecdf4af621bb88bd7a3ebe8f0f963bb7dad072623d908","contract":["d := diskv.New(diskv.Options{BasePath: dir, Transform: flatTransform, CacheSizeMax: 1024 * 1024})","d.WriteString(key, val) == nil","d.Has(key) == true","d.ReadString(key) == val","d.Read(key) == ([]byte(val), nil)","d.Erase(key) == nil","d.Has(key) == false"],"goal":"verify github.com/peterbourgon/diskv/v3.Diskv in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1","kind":"HOW","packages":["pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1"],"schemaVersion":1,"symbols":["github.com/peterbourgon/diskv/v3.Diskv"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1"],"schemaVersion":1,"subject":"pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1","symbols":["github.com/peterbourgon/diskv/v3.Diskv"],"verifierAdapter":"golang@1"}

module sample

go 1.20

require github.com/peterbourgon/diskv/v3 v3.0.1

require github.com/google/btree v1.0.0 // indirect

github.com/google/btree v1.0.0 h1:0udJVsspx3VBr5FwtLhQQtuAsVc79tTq0ocGIPAU6qo=
github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
github.com/peterbourgon/diskv/v3 v3.0.1 h1:x06SQA46+PKIUftmEujdwSEpIx8kR+M9eLYsUxeYveU=
github.com/peterbourgon/diskv/v3 v3.0.1/go.mod h1:kJ5Ny7vLdARGU3WUuy6uzO6T0nb/2gWcT1JiBvRmb5o=

package sample

import (
	"github.com/peterbourgon/diskv/v3"
)

// Store wraps diskv.Diskv to provide key-value storage.
type Store struct {
	disk *diskv.Diskv
}

// NewStore initializes a new Store backed by diskv.Diskv.
func NewStore(basePath string) *Store {
	flatTransform := func(s string) []string {
		return []string{}
	}

	d := diskv.New(diskv.Options{
		BasePath:     basePath,
		Transform:    flatTransform,
		CacheSizeMax: 1024 * 1024,
	})

	return &Store{disk: d}
}

// Write stores the key and string value.
func (s *Store) Write(key, val string) error {
	return s.disk.WriteString(key, val)
}

// Read retrieves the string value for a key.
func (s *Store) Read(key string) string {
	return s.disk.ReadString(key)
}

// Has checks whether a key exists in storage.
func (s *Store) Has(key string) bool {
	return s.disk.Has(key)
}

// Erase deletes the key and its value.
func (s *Store) Erase(key string) error {
	return s.disk.Erase(key)
}

// Diskv returns the underlying diskv instance.
func (s *Store) Diskv() *diskv.Diskv {
	return s.disk
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/peterbourgon/diskv/v3.Diskv in pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/peterbourgon/diskv/v3@v3.0.1"
  ],
  "symbols": [
    "github.com/peterbourgon/diskv/v3.Diskv"
  ]
}

package main

import (
	"fmt"
	"os"

	"github.com/peterbourgon/diskv/v3"
)

func main() {
	dir, err := os.MkdirTemp("", "diskv-contract-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(dir)

	flatTransform := func(s string) []string {
		return []string{}
	}

	d := diskv.New(diskv.Options{
		BasePath:     dir,
		Transform:    flatTransform,
		CacheSizeMax: 1024 * 1024,
	})
	if d == nil {
		fmt.Fprintf(os.Stderr, "diskv.New returned nil\n")
		os.Exit(1)
	}

	key := "example-key"
	val := "example-val"

	if err := d.WriteString(key, val); err != nil {
		fmt.Fprintf(os.Stderr, "WriteString failed: %v\n", err)
		os.Exit(1)
	}

	if !d.Has(key) {
		fmt.Fprintf(os.Stderr, "Has returned false for existing key\n")
		os.Exit(1)
	}

	got := d.ReadString(key)
	if got != val {
		fmt.Fprintf(os.Stderr, "ReadString got %q, want %q\n", got, val)
		os.Exit(1)
	}

	raw, err := d.Read(key)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Read failed: %v\n", err)
		os.Exit(1)
	}
	if string(raw) != val {
		fmt.Fprintf(os.Stderr, "Read returned unexpected bytes\n")
		os.Exit(1)
	}

	if err := d.Erase(key); err != nil {
		fmt.Fprintf(os.Stderr, "Erase failed: %v\n", err)
		os.Exit(1)
	}

	if d.Has(key) {
		fmt.Fprintf(os.Stderr, "Has returned true after Erase\n")
		os.Exit(1)
	}

	fmt.Println("contract passed")
}