github.com/prometheus/procfs v0.22.0: FS.Diskstats

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 procfs.FS.Diskstats in pkg:golang/github.com/prometheus/procfs@v0.22.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/procfs@v0.22.0
Demonstrate these symbols/APIs:
  - procfs.FS.Diskstats
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:6f5869fec8fc9902bef17fd9c4db3e769f4d7ab8abe75835b9a30cb333b363f1","contract":["procfs.NewDefaultFS() returns (FS, error) where error is nil","blockdevice.NewDefaultFS() returns (FS, error) where error is nil","fs.ProcDiskstats() returns ([]Diskstats, error) where error is nil","fs.ProcDiskstats() returns a non-empty slice of diskstats on a running system","each Diskstats in diskstats has non-empty DeviceName and positive IoStatsCount"],"goal":"verify procfs.FS.Diskstats in pkg:golang/github.com/prometheus/procfs@v0.22.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/procfs@v0.22.0"],"schemaVersion":1,"symbols":["procfs.FS.Diskstats"]},"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/prometheus/procfs@v0.22.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/procfs@v0.22.0","symbols":["procfs.FS.Diskstats"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require github.com/prometheus/procfs v0.22.0

require golang.org/x/sys v0.47.0 // indirect

github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/prometheus/procfs v0.22.0 h1:6q9+/JL9IKAPbCmBrv9n5O5Ty3NKnciV5X7YGw0oics=
github.com/prometheus/procfs v0.22.0/go.mod h1:CvmFr/GVhIjIvWJZW3tgkODBQMRIf0EyWMQLHCHab58=
golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
	"github.com/prometheus/procfs/blockdevice"
)

// GetDefaultFS initializes and returns the default procfs filesystem.
func GetDefaultFS() (procfs.FS, error) {
	return procfs.NewDefaultFS()
}

// GetBlockDeviceFS initializes and returns the default blockdevice filesystem.
func GetBlockDeviceFS() (blockdevice.FS, error) {
	return blockdevice.NewDefaultFS()
}

// GetDiskstats reads and returns block device statistics from the proc filesystem.
func GetDiskstats() ([]blockdevice.Diskstats, error) {
	fs, err := blockdevice.NewDefaultFS()
	if err != nil {
		return nil, fmt.Errorf("blockdevice.NewDefaultFS failed: %w", err)
	}
	return fs.ProcDiskstats()
}

func main() {
	pfs, err := GetDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error initializing procfs: %v\n", err)
		os.Exit(1)
	}
	_ = pfs

	stats, err := GetDiskstats()
	if err != nil {
		fmt.Fprintf(os.Stderr, "error reading diskstats: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Discovered %d block device(s)\n", len(stats))
	for i, s := range stats {
		if i >= 3 {
			break
		}
		fmt.Printf("Device: %s (Major: %d, Minor: %d), ReadIOs: %d, WriteIOs: %d, IoStatsCount: %d\n",
			s.DeviceName, s.MajorNumber, s.MinorNumber, s.ReadIOs, s.WriteIOs, s.IoStatsCount)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify procfs.FS.Diskstats in pkg:golang/github.com/prometheus/procfs@v0.22.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/procfs@v0.22.0"
  ],
  "symbols": [
    "procfs.FS.Diskstats"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
	"github.com/prometheus/procfs/blockdevice"
)

func main() {
	// 1. procfs.NewDefaultFS() returns (FS, error) where error is nil
	_, err := procfs.NewDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: procfs.NewDefaultFS failed: %v\n", err)
		os.Exit(1)
	}

	// 2. blockdevice.NewDefaultFS() returns (FS, error) where error is nil
	fs, err := blockdevice.NewDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: blockdevice.NewDefaultFS failed: %v\n", err)
		os.Exit(1)
	}

	// 3. fs.ProcDiskstats() returns ([]Diskstats, error) where error is nil
	stats, err := fs.ProcDiskstats()
	if err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: fs.ProcDiskstats failed: %v\n", err)
		os.Exit(1)
	}

	// 4. fs.ProcDiskstats() returns a non-empty slice of diskstats on a running system
	if len(stats) == 0 {
		fmt.Fprintf(os.Stderr, "FAIL: expected non-empty diskstats slice\n")
		os.Exit(1)
	}

	// 5. each Diskstats in diskstats has non-empty DeviceName and positive IoStatsCount
	for _, s := range stats {
		if s.DeviceName == "" {
			fmt.Fprintf(os.Stderr, "FAIL: expected non-empty DeviceName\n")
			os.Exit(1)
		}
		if s.IoStatsCount <= 0 {
			fmt.Fprintf(os.Stderr, "FAIL: expected positive IoStatsCount, got %d\n", s.IoStatsCount)
			os.Exit(1)
		}
	}

	fmt.Println("PASS: all contract assertions passed")
}