mongo-lock

Distributed lock library for C#/.NET using MongoDB.

Notidar.MongoDB.Lock is a core library that provides a simple way to create distributed locks for simple apps. LockStore can be used for direct lock manipulation, while LockService provides a high level abstraction. Include extensions for creating collection and indexes.

Notidar.MongoDB.Lock.Extensions is a library that provides all required extensions to use the library with Microsoft.Extensions.DependencyInjection.

Features

• Distributed locks using MongoDB
  • Exclusive locks
  • Shared locks
  • Semaphore like usage with shared locks
• High level abstraction with LockService
• Low level manipulation with LockStore
• Optional MongoDB collection auto cleanup for expired locks based on TTL index
• Flexible lock configuration with LockOptions

Usage

With IServiceCollection with high level manipulations

...
services
    .AddMongoDb(configuration.GetSection(nameof(DatabaseOptions))) // if MongoDB not registered
    .AddMongoLocks(configuration.GetSection(nameof(LockSettings))); // add all required services for locks
...

// resolve lock service
var lockService = sp.GetRequiredService<ILockService>();

await using (var sharedLock1 = await lockService.SharedLockAsync(resourceId, operationCancellationToken))
{
    // shared lock1 acquired
    await DoSomethingAsync(sharedLock1.HealthToken); // use `sharedLock1.HealthToken` to check if lock is still valid
    await using (var sharedLock2 = await lockService.SharedLockAsync(resourceId, operationCancellationToken))
    {
        // shared lock2 acquired
        await DoSomethingAsync2(sharedLock2.HealthToken); // use `sharedLock2.HealthToken` to check if lock is still valid
    }
    // shared lock2 released
}
// shared lock1 released

await using (var exclusiveLock = await lockService.ExclusiveLockAsync(resourceId, operationCancellationToken))
{
    // exclusive lock acquired
    await DoSomethingExclusivelyAsync(exclusiveLock.HealthToken); // use `exclusiveLock.HealthToken` to check if lock is still valid
}
// exclusive lock released

Simple console app with low level manipulations

var client = new MongoClient(connectionString);
var database = client.GetDatabase("cli-test");

var lockStore = new LockStore(database.GetCollection<Resource>("locks")); // Resource defined in Notidar.MongoDB.Lock.Stores
var lockService = new LockService(lockStore); // in case you need high level manipulations

// low level manipulation
var resourceResult = await lockStore.ExclusiveLockAsync("resourceId-1", "lockId-1", TimeSpan.FromSeconds(60)); // exlusive lock
if (resource?.ExclusiveLock?.LockId == "lockId-1")
{
    // exclusive locked aquired
    await lockStore.ExclusiveUnlockAsync("resourceId-1", "lockId-1"); // exlusive release
}

var resourceFirstSharedResult = await lockStore.SharedLockAsync("resourceId-1", "lockId-2", TimeSpan.FromSeconds(60));
var resourceSecondSharedResult = await lockStore.SharedLockAsync("resourceId-1", "lockId-3", TimeSpan.FromSeconds(60), sharedLockLimit: 10);
if (resourceFirstSharedResult?.SharedLocks?.Any(x => x.LockId == "lockId-2") && resourceSecondSharedResult?.SharedLocks?.Any(x => x.LockId == "lockId-3"))
{
    // both shared locked aquired
    await lockStore.SharedUnlockAsync("resourceId-1", "lockId-2"); // shared release
    await lockStore.SharedUnlockAsync("resourceId-1", "lockId-3"); // shared release
}

See samples folder for more examples.

Roadmap (Contributions are welcome)

Contributions are welcome! If you are interested in contributing towards a new or existing issue, please let me know via comments on the issue so that I can help you get started and avoid wasted effort on your part.

• Add support auto cleanup for expired locks
• Add support for infinite locks (locks that never expire)
• Add support for optional lock re-entry
• Add logging support
• Add CLI for managing locks. (e.g. mongo-lock --list, mongo-lock --delete <lockId>)
• Add support for MongoDB unlock detection. Based either MongoDB Capped Collections with signals or on MongoDB Change Streams (e.g. LockService.WaitForUnlockAsync(lockId, timeout))
• Improve unit test coverage

License

MIT License