Lifetimesedit

If you are using an IOC/Dependency Injection container, it’s always useful to know the best practices around the lifetime of your objects.

In general, we advise folks to register an ElasticClient instance as a singleton; the client is thread safe, so sharing an instance across threads is fine.

The actual moving part that benefits from being a singleton is ConnectionSettings because caches are per ConnectionSettings.

In some applications ,it could make perfect sense to have multiple ElasticClient instances registered with different connection settings such as when your application connects to two different Elasticsearch clusters.

Important

Due to the semantic versioning of Elasticsearch.Net and NEST and their alignment to versions of Elasticsearch, all instances of ElasticClient and Elasticsearch clusters that are connected to must be on the same major version

Let’s demonstrate which components are disposed by creating our own derived ConnectionSettings, IConnectionPool and IConnection types

class AConnectionSettings : ConnectionSettings
{
    public AConnectionSettings(IConnectionPool pool, IConnection connection)
        : base(pool, connection)
    { }

    public bool IsDisposed { get; private set; }

    protected override void DisposeManagedResources()
    {
        this.IsDisposed = true;
        base.DisposeManagedResources();
    }
}

class AConnectionPool : SingleNodeConnectionPool
{
    public AConnectionPool(Uri uri, IDateTimeProvider dateTimeProvider = null) : base(uri, dateTimeProvider) { }

    public bool IsDisposed { get; private set; }

    protected override void DisposeManagedResources()
    {
        this.IsDisposed = true;
        base.DisposeManagedResources();
    }
}

class AConnection : InMemoryConnection
{
    public bool IsDisposed { get; private set; }

    protected override void DisposeManagedResources()
    {
        this.IsDisposed = true;
        base.DisposeManagedResources();
    }
}

ConnectionSettings, IConnectionPool and IConnection all explictily implement IDisposable

var connection = new AConnection();
var connectionPool = new AConnectionPool(new Uri("http://localhost:9200"));
var settings = new AConnectionSettings(connectionPool, connection);
settings.IsDisposed.Should().BeFalse();
connectionPool.IsDisposed.Should().BeFalse();
connection.IsDisposed.Should().BeFalse();

Disposing an instance of ConnectionSettings will also dispose the IConnectionPool and IConnection it uses

var connection = new AConnection();
var connectionPool = new AConnectionPool(new Uri("http://localhost:9200"));
var settings = new AConnectionSettings(connectionPool, connection);
using (settings) { } 
settings.IsDisposed.Should().BeTrue();
connectionPool.IsDisposed.Should().BeTrue();
connection.IsDisposed.Should().BeTrue();

force the settings to be disposed