What is lock-free-guide?

A set of guidelines for writing and reviewing C11 shared-memory code that uses multiple threads, atomic operations, and lock-free or wait-free data structures.

Use it when working on atomic operations, compare-and-exchange code, concurrent queues or stacks, memory reclamation, or synchronization in systems software.

It helps avoid data races, incorrect memory ordering, unsafe compare-and-exchange loops, and freeing shared nodes too early. It also warns that lock-free code should be measured rather than assumed to be faster.

lock-free-guide — Skill for Claude Code by xonovex/platform

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add xonovex/platform --skill lock-free-guide

Clone the repo

git clone --depth 1 https://github.com/xonovex/platform

Made for: Claude Code.

Or install xonovex-native, the plugin that ships this one along with the rest of its 7 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/xonovex/platform/lock-free-guide/github.svg)](https://agentmods.dev/skills/xonovex/platform/lock-free-guide)

Your own site

<a href="https://agentmods.dev/skills/xonovex/platform/lock-free-guide"><img src="https://agentmods.dev/badge/skills/xonovex/platform/lock-free-guide/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/xonovex/platform/lock-free-guide"><img src="https://agentmods.dev/badge/skills/xonovex/platform/lock-free-guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,436 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00103	$0.01436
Opus 5.5	$0.00041	$0.00574
Sonnet 5.5	$0.00021	$0.00287
Haiku 4.5	$0.00010	$0.00144

Measured 7d ago against content hash 78e9542ef18d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

lock-free-guide scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packages/runtime/plugin/plugin-native/skills/lock-free-guide/SKILL.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Lock-Free / Wait-Free Concurrency Guidelines

Choose concurrency primitives by their progress guarantees, memory ordering, and reclamation requirements; verify them under contention.

Requirements

C11 atomics (<stdatomic.h>); applies to systems code with atomic, threading, and job-scheduling primitives.

Essentials

No data races - Every shared mutable location touched by 2+ threads is atomic or lock-protected, see references/memory-model.md
CAS loops retry - compare_exchange_weak in a loop; reload the expected value on failure, see references/atomics-and-cas.md
Lock-free needs reclamation - Removing a node from a shared structure is not freeing it, see references/safe-memory-reclamation.md
Measure, do not assume - Locks are often faster; profile before going lock-free, see references/progress-guarantees.md

Memory model

Progress guarantees - wait-free ⊃ lock-free ⊃ obstruction-free ⊃ blocking, see references/progress-guarantees.md
Happens-before - Acquire/release builds the ordering that makes writes visible, see references/memory-model.md
Orderings - relaxed/acquire/release/acq_rel/seq_cst + fences, see references/memory-ordering.md

Building blocks

Atomics & CAS - load/store/exchange/fetch_*/compare_exchange, weak vs strong, see references/atomics-and-cas.md
ABA problem - CAS can't see a value changed away and back; tag pointers or reclaim safely, see references/aba-problem.md
False sharing - Pad/align hot per-thread and atomic fields to their own cache line, see references/false-sharing.md

Data structures

SPSC ring - One producer, one consumer, no CAS, see references/spsc-ring-buffer.md
MPSC queue - Intrusive: producers XCHG tail, consumer walks next, see references/mpsc-queue.md
MPMC bounded - Per-cell sequence numbers, ABA-free, see references/mpmc-bounded-queue.md
Lock-free stack - CAS on head; needs reclamation for pop, see references/lock-free-stack.md

Read the full file on GitHub · 70 lines

Files

What ships with it

18 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

7d ago Changed · +2 lines 78e9542ef18d
1mo ago First seen · 68 lines · 103 tokens per session scan A c625e62c4f8f

Subscribe to this mod's changes

lock-free-guide is a skill published in the GitHub repository xonovex/platform (6 stars, last pushed 5d ago), licensed MIT. It adds 103 tokens to every session and 1,436 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-08.

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lock-free-guide