AsyncResourcePool

Thread-safe, non-blocking, managed pool of re-usable resources, with a specified minimum and optional maximum number of resources, and optional expiry time for resources to be cleaned up if not used for a time.

Installation

dotnet add package AsyncResourcePool

Options

Behaviour of AsyncResourcePool can be specified using AsyncResourcePoolOptions.

Property	Default	Description
MinNumResources	N/A	The minimum number of resources that will be maintained by the pool. This number of resources will be created regardless of whether or not they are requested. If a resource is requested an allocated, an additional resource will be created to maintain the pool size.
MaxNumResources	int.MaxValue	The maximum number of resources that the pool is allowed to create.
ResourcesExpireAfter	null	If a resource is unused for this time, it will be dispsosed. If this causes the number of available resources to drop below the minimum, additional resources will be created to replace the disposed ones.
MaxNumResourceCreationAttempts	3	Maximum number of attempts for creating a resource before an exception is thrown and passed back to the requestor
ResourceCreationRetryInterval	1 second	Amount of time to wait after a failed resource creation attempt before trying again

Example usage: Connection Pool for Snowflake Connector for .NET

https://github.com/snowflakedb/snowflake-connector-net

1. Define a ConnectionPool class which consumes AsyncResourcePool internally

public sealed class ConnectionPool
{
    private readonly IAsyncResourcePool<SnowflakeDbConnection> _resourcePool;

    public ConnectionPool(string connectionString)
    {
        var connectionFactory = GetConnectionFactoryFunc(connectionString);

        var asyncResourcePoolOptions = new AsyncResourcePoolOptions(
            minNumResources: 20,
            resourcesExpireAfter: TimeSpan.FromMinutes(15));

        _resourcePool = new AsyncResourcePool<SnowflakeDbConnection>(connectionFactory, asyncResourcePoolOptions);
    }

    public Task<ReusableResource<SnowflakeDbConnection>> Get(CancellationToken cancellationToken) => _resourcePool.Get(cancellationToken);

    public void Dispose() => _resourcePool.Dispose();

    private static Func<Task<SnowflakeDbConnection>> GetConnectionFactoryFunc(string connectionString)
    {
        return async () =>
        {
            var conn = new SnowflakeDbConnection
            {
                ConnectionString = connectionString
            };

            await conn.OpenAsync();

            return conn;
        };
    }
}

2. Optionally register ConnectionPool as Singleton in dependency injection configuration

services.AddSingleton<ConnectionPool>(sp => new ConnectionPool(...));

3. Consume ConnectionPool

public class ConnectionConsumer
{
    private readonly ConnectionPool _connectionPool;

    public ConnectionConsumer(ConnectionPool connectionPool) {
        _connectionPool = connectionPool;
    }

    public async Task DoSomething(CancellationToken cancellationToken) {
        using (var reusableConnection = await _connectionPool.Get(cancellationToken)) {
            var connection = reusableConnection.Resource;
            // Do something with the connection
        }
    }
}