Skip to main content

Configuring Semaphore adapters

MemorySemaphoreAdapter​

To use the MemorySemaphoreAdapter you only need to create instance of it:

./samples/memory-semaphore-adapter.ts
import { MemorySemaphoreAdapter } from "eridu-tech/semaphore/memory-semaphore-adapter";

export const memorySemaphoreAdapter = new MemorySemaphoreAdapter();

You can also provide an Map that will be used for storing the data in memory:

./samples/memory-semaphore-adapter-with-map.ts
import { MemorySemaphoreAdapter } from "eridu-tech/semaphore/memory-semaphore-adapter";

const map = new Map<any, any>();
const memorySemaphoreAdapter = new MemorySemaphoreAdapter(map);
info

MemorySemaphoreAdapter lets you test your app without external dependencies like Redis, ideal for local development, unit tests, integration tests and fast E2E test for the backend application.

danger

Note the MemorySemaphoreAdapter is limited to single process usage and cannot be shared across multiple servers or processes.

Settings​

To clean up expired semaphore keys, call removeAllExpired at a regular interval (for example, using a cron job):

./samples/memory-semaphore-remove-all-expired.ts
import { MemorySemaphoreAdapter } from "eridu-tech/semaphore/memory-semaphore-adapter";

const memorySemaphoreAdapter = new MemorySemaphoreAdapter();

// Remove all expired semaphore keys manually.
await memorySemaphoreAdapter.removeAllExpired();
info

To remove the semaphore map and all stored semaphore data, use deInit method:

./samples/memory-semaphore-adapter-deinit.ts
import { memorySemaphoreAdapter } from "./memory-semaphore-adapter.js";

await memorySemaphoreAdapter.deInit();

MongodbSemaphoreAdapter​

To use the MongodbSemaphoreAdapter, you'll need to:

  1. Install the required dependency: mongodb package.

Setup​

Connect to MongoDB:

./samples/mongodb-semaphore-adapter-setup.ts
import { MongoClient } from "mongodb";

const client = await MongoClient.connect("YOUR_MONGODB_CONNECTION_STRING");
export const database = client.db("database");
info

The database setting also accepts a TransactionContext, which makes the adapter transaction aware. Adapters given the same instance share the same transaction when available.

Usage​

Create the adapter:

./samples/mongodb-semaphore-adapter.ts
import { MongodbSemaphoreAdapter } from "eridu-tech/semaphore/mongodb-semaphore-adapter";
import { database } from "./mongodb-semaphore-adapter-setup.js";

export const mongodbSemaphoreAdapter = new MongodbSemaphoreAdapter({
    database,
});

// You need initialize the adapter once before using it.
// During the initialization the indexes will be created
await mongodbSemaphoreAdapter.init();

You can change the collection name:

./samples/mongodb-semaphore-collection-name.ts
import { MongodbSemaphoreAdapter } from "eridu-tech/semaphore/mongodb-semaphore-adapter";
import { database } from "./mongodb-semaphore-adapter-setup.js";

const mongodbSemaphoreAdapter = new MongodbSemaphoreAdapter({
    database,
    // By default "semaphore" is used as collection name
    collectionName: "my-semaphore",
});

await mongodbSemaphoreAdapter.init();

You can change the collection settings:

./samples/mongodb-semaphore-collection-settings.ts
import { MongodbSemaphoreAdapter } from "eridu-tech/semaphore/mongodb-semaphore-adapter";
import { database } from "./mongodb-semaphore-adapter-setup.js";

const mongodbSemaphoreAdapter = new MongodbSemaphoreAdapter({
    database,
    // You configure additional collection settings
    collectionSettings: {},
});

await mongodbSemaphoreAdapter.init();
info

To remove the semaphore collection and all stored semaphore data, use deInit method:

./samples/mongodb-semaphore-adapter-deinit.ts
import { mongodbSemaphoreAdapter } from "./mongodb-semaphore-adapter.js";

await mongodbSemaphoreAdapter.deInit();
danger

Note in order to use MongodbSemaphoreAdapter correctly, ensure you use a single, consistent database across all server instances or processes.

RedisSemaphoreAdapter​

To use the RedisSemaphoreAdapter, you'll need to:

  1. Install the required dependency: ioredis package.

Setup​

Connect to Redis:

./samples/redis-semaphore-adapter-setup.ts
import { Redis } from "ioredis";

export const database = new Redis("YOUR_REDIS_CONNECTION_STRING");

Usage​

Create the adapter:

./samples/redis-semaphore-adapter.ts
import { RedisSemaphoreAdapter } from "eridu-tech/semaphore/redis-semaphore-adapter";
import { database } from "./redis-semaphore-adapter-setup.js";

const redisSemaphoreAdapter = new RedisSemaphoreAdapter(database);
danger

Note in order to use RedisSemaphoreAdapter correctly, ensure you use a single, consistent database across all server instances or processes.

KyselySemaphoreAdapter​

To use the KyselySemaphoreAdapter, you'll need to:

  1. Use database provider that has support for transactions.
  2. Install the required dependency: kysely package.

Setup​

Create a function that creates the TransactionContext by wrapping a Kysely instance in a KyselyTransactionAdapter:

./samples/kysely-semaphore-adapter-setup.ts
import { ExecutionContext } from "eridu-tech/execution-context";
import { AlsExecutionContextAdapter } from "eridu-tech/execution-context/als-execution-context-adapter";
import { contextToken } from "eridu-tech/execution-context/contracts";
import { TransactionContext } from "eridu-tech/transaction-context";
import { KyselyTransactionAdapter } from "eridu-tech/transaction-context/kysely-transaction-adapter";
import type { ITransactionContext } from "eridu-tech/transaction-context/contracts";
import type { Kysely } from "kysely";

const executionContext = new ExecutionContext(new AlsExecutionContextAdapter());

// `KyselySemaphoreAdapter` is transaction aware: it runs every semaphore
// operation through the `current` client of this context, which is the
// transaction-scoped client while a transaction is active and the base client
// otherwise.
export function createTransactionContext(
    kysely: Kysely<any>,
): ITransactionContext<Kysely<any>> {
    return new TransactionContext<Kysely<any>>({
        token: contextToken("kysely"),
        adapter: new KyselyTransactionAdapter({
            database: kysely,
        }),
        executionContext,
    });
}
info

The transactionContext setting makes the adapter transaction aware. Adapters given the same instance share the same transaction when available.

With Sqlite​

You will need to install better-sqlite3 package:

./samples/kysely-semaphore-sqlite.ts
import { KyselySemaphoreAdapter } from "eridu-tech/semaphore/kysely-semaphore-adapter";
import Sqlite from "better-sqlite3";
import { Kysely, SqliteDialect } from "kysely";
import { createTransactionContext } from "./kysely-semaphore-adapter-setup.js";

const database = new Sqlite("DATABASE_NAME.db");
const kysely = new Kysely<any>({
    dialect: new SqliteDialect({
        database,
    }),
});
const transactionContext = createTransactionContext(kysely);
export const kyselySemaphoreAdapter = new KyselySemaphoreAdapter({
    transactionContext,
});

// You need initialize the adapter once before using it.
// During the initialization the schema will be created
await kyselySemaphoreAdapter.init();
danger

Note using KyselySemaphoreAdapter with sqlite is limited to single server usage and cannot be shared across multiple servers but it can be shared between different processes. To use it correctly, ensure all process instances access the same persisted database.

With Postgres​

You will need to install pg package:

./samples/kysely-semaphore-postgres.ts
import { KyselySemaphoreAdapter } from "eridu-tech/semaphore/kysely-semaphore-adapter";
import { Pool } from "pg";
import { Kysely, PostgresDialect } from "kysely";
import { createTransactionContext } from "./kysely-semaphore-adapter-setup.js";

const database = new Pool({
    database: "DATABASE_NAME",
    host: "DATABASE_HOST",
    user: "DATABASE_USER",
    // DATABASE port
    port: 5432,
    password: "DATABASE_PASSWORD",
    max: 10,
});
const kysely = new Kysely<any>({
    dialect: new PostgresDialect({
        pool: database,
    }),
});
const transactionContext = createTransactionContext(kysely);
const kyselySemaphoreAdapter = new KyselySemaphoreAdapter({
    transactionContext,
});

// You need initialize the adapter once before using it.
// During the initialization the schema will be created
await kyselySemaphoreAdapter.init();
danger

Note in order to use KyselySemaphoreAdapter with postgres correctly, ensure you use a single, consistent database across all server instances. This means you can't use replication.

With Mysql​

You will need to install mysql2 package:

./samples/kysely-semaphore-mysql.ts
import { KyselySemaphoreAdapter } from "eridu-tech/semaphore/kysely-semaphore-adapter";
import { createPool } from "mysql2";
import { Kysely, MysqlDialect } from "kysely";
import { createTransactionContext } from "./kysely-semaphore-adapter-setup.js";

const database = createPool({
    host: "DATABASE_HOST",
    // Database port
    port: 3306,
    database: "DATABASE_NAME",
    user: "DATABASE_USER",
    password: "DATABASE_PASSWORD",
    connectionLimit: 10,
});
const kysely = new Kysely<any>({
    dialect: new MysqlDialect({
        pool: database,
    }),
});
const transactionContext = createTransactionContext(kysely);
const kyselySemaphoreAdapter = new KyselySemaphoreAdapter({
    transactionContext,
});

// You need initialize the adapter once before using it.
// During the initialization the schema will be created
await kyselySemaphoreAdapter.init();
danger

Note in order to use KyselySemaphoreAdapter with mysql correctly, ensure you use a single, consistent database across all server instances. This means you can't use replication.

With Libsql​

You will need to install @libsql/kysely-libsql package:

./samples/kysely-semaphore-libsql.ts
import { KyselySemaphoreAdapter } from "eridu-tech/semaphore/kysely-semaphore-adapter";
import { LibsqlDialect } from "@libsql/kysely-libsql";
import { Kysely } from "kysely";
import { createTransactionContext } from "./kysely-semaphore-adapter-setup.js";

const kysely = new Kysely<any>({
    dialect: new LibsqlDialect({
        url: "DATABASE_URL",
    }),
});
const transactionContext = createTransactionContext(kysely);
const kyselySemaphoreAdapter = new KyselySemaphoreAdapter({
    transactionContext,
});

// You need initialize the adapter once before using it.
// During the initialization the schema will be created
await kyselySemaphoreAdapter.init();
danger

Note in order to use KyselySemaphoreAdapter with libsql correctly, ensure you use a single, consistent database across all server instances. This means you can't use libsql embedded replicas.

Settings​

To clean up expired semaphore keys, call removeAllExpired at a regular interval (for example, using a cron job):

./samples/kysely-semaphore-remove-all-expired.ts
import { kyselySemaphoreAdapter } from "./kysely-semaphore-sqlite.js";

// Remove all expired semaphore keys manually.
await kyselySemaphoreAdapter.removeAllExpired();
info

To remove the semaphore table and all stored semaphore data, use deInit method:

./samples/kysely-semaphore-adapter-deinit.ts
import { kyselySemaphoreAdapter } from "./kysely-semaphore-sqlite.js";

await kyselySemaphoreAdapter.deInit();

NoOpSemaphoreAdapter​

The NoOpSemaphoreAdapter is a no-operation implementation, it performs no actions when called:

./samples/no-op-semaphore-adapter.ts
import { NoOpSemaphoreAdapter } from "eridu-tech/semaphore/no-op-semaphore-adapter";

const noOpSemaphoreAdapter = new NoOpSemaphoreAdapter();
info

The NoOpSemaphoreAdapter is useful when you want to mock out or disable your SemaphoreFactory instance.

Further information​

For further information refer to eridu-tech/semaphore API docs.