locker.md

🔒 Locker Guide

🚀 Quick Start Guide for file locking and process concurrency with LuaDoTheWorld

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📋 What You'll Learn

• ✅ How to lock and unlock files
• ✅ How to manage concurrency between processes
• ✅ How to use lockers in forked processes

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🛠️ Prerequisites

• LuaDoTheWorld installed and required in your script

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🔒 Lock and Unlock a File

local dtw = require("luaDoTheWorld/luaDoTheWorld")

local locker = dtw.newLocker()
locker.lock("a.txt")
-- Do something with the locked file
locker.unlock("a.txt")

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🤖 Locking in Multiple Processes (Fork Example)

Create 30 forks, each writing its number to a file safely using a locker:

local dtw = require("luaDoTheWorld/luaDoTheWorld")

local all_forks = {}
local total_forks = 30

dtw.remove_any("a.txt")

for i = 1, total_forks do
    local fork = dtw.newFork(function()
        local locker = dtw.newLocker()
        locker.lock("a.txt")
        local old = dtw.load_file("a.txt")
        if old == nil then old = "" end
        old = old .. i .. "\n"
        dtw.write_file("a.txt", old)
        locker.unlock("a.txt")
    end)
    all_forks[i] = fork
end

-- Wait for all child processes to finish
for i = 1, total_forks do
    all_forks[i].wait(-1)
end

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📚 Quick Reference

Function	What it does	Example
dtw.newLocker()	Create a new locker	local locker = dtw.newLocker()
locker.lock(path)	Lock a file	locker.lock("a.txt")
locker.unlock(path)	Unlock a file	locker.unlock("a.txt")
dtw.newFork(fn)	Create a new process	dtw.newFork(function() ... end)

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📝 Notes

• Lockers prevent file access conflicts between processes (not threads).
• Only works if all processes use LuaDoTheWorld's locker system.

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🆘 Need Help?

• 📖 Check the main SDK documentation
• 🔍 Look at other example scripts in the SDK
• 🐛 Report issues on our GitHub repository

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