Package Exports
- mutex-server
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Readme
Mutex Server
1. Outline
Critical sections in the network level.
The mutex-server is an npm module that can be used for building a mutex server. When you need to control a critical section on the entire system level, like distributed processing system using the network communications, this mutex-server can be a good solution.
Opens a mutex-server and let clients to connect to the mutex-server. When sharing network level critical sections through the mutex-server, you don't need to worry about any accident like sudden network disconnection by power outage. If a client has been disconnected by accident, all of the locks had been acquired by the client would be automatically released.
2. Features
2.1. Network
2.2. Components
- Solid Components
- Adaptor Components
- Safety Helpers
2.3. Dependencies
3. Usage
3.1. Server
Building a mutex server is very simple like below:
import { MutexServer } from "mutex-server";
async function main(): Promise<void>
{
let server: MutexServer<string, null> = new MutexServer();
await server.open(44114, async acceptor =>
{
if (acceptor.header === "qweqwe123!")
await acceptor.accept(null);
else
await acceptor.reject();
});
}3.2. Client
Using the mutex server is also easy too. However, be careful when using the remote mutex. If you forget unlocking the remote mutex, other clients would be suffered by your mistake.
import { MutexConnector, RemoteMutex } from "mutex-server";
async function main(): Promise<void>
{
// CONNECT TO THE SERVER
let connector: MutexConnector<string, null> = new MutexConnector("qweqwe123!", null);
await connector.connect("http://127.0.0.1:44114");
//----
// USE MUTEX
//----
// GET NAMED MUTEX
let mutex: RemoteMutex = connector.getMutex("someName");
// WRITE-LOCK
await mutex.lock();
{
// ...
// DO SOMETHING
// ...
}
await mutex.unlock();
// READ-LOCK
await mutex.lock_shared();
{
// ...
// DOM SOMETHING
// ...
}
await mutex.unlock_shared();
await connector.close();
}3.3. Learn from Example
import ms from "mutex-server";
import std from "tstl";
const PASSWORD = "qweqwe123!";
const PORT = 37119;
async function client(character: string): Promise<void>
{
// CONNECT TO THE SERVER
let connector: ms.MutexConnector<string, null> = new ms.MutexConnector(PASSWORD, null);
await connector.connect(`ws://127.0.0.1:${PORT}`);
// GET LOCK
let mutex: ms.RemoteMutex = await connector.getMutex("printer");
await mutex.lock();
// PRINTS A LINE VERY SLOWLY MONOPOLYING THE MUTEX
for (let i: number = 0; i < 20; ++i)
{
process.stdout.write(character);
await std.sleep_for(50);
}
process.stdout.write("\n");
// RANDOM UNLOCK
if (Math.random() < 0.5)
await mutex.unlock();
// ALTHOUGH THE CLIENT DOES NOT RELEASE THE LOCK
// SERVER WILL UNLOCK IT AUTOMATICALLY AFTER THE DISCONNECTION
await connector.close();
}
async function main(): Promise<void>
{
// OPEN SERVER
let server: ms.MutexServer<string, null> = new ms.MutexServer();
await server.open(PORT, async acceptor =>
{
if (acceptor.header === PASSWORD)
await acceptor.accept(null);
else
await acceptor.reject();
});
// CREATE 10 CLIENTS LOCKING MUTEX
let promises: Promise<void>[] = [];
for (let i: number = 0; i < 4; ++i)
{
let character: string = std.randint(0, 9).toString();
promises.push( client(character) );
}
// WAIT THE CLIENTS TO BE DISCONNCTED AND CLOSE SERVER
await Promise.all(promises);
await server.close();
}
main();4. Appendix
4.1. Repositories
4.2. Documents
- API Docs: https://mutex.dev/api