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POIDbConnection lifecycle management with persistent HTTP connections
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  1. POIDbConnection lifecycle management with persistent HTTP connections
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    copied!<p>I have a problem managing the lifetime of open database connections with StructureMap scoped to <code>HttpContext</code> when there are persistent HTTP connections in my ASP.NET MVC application, like SignalR hubs.</p> <p>My DI container, StructureMap, injects an open <code>IDbConnection</code> into several services. To ensure that these database connections are closed and properly disposed of, I call <code>ObjectFactory.ReleaseAndDisposeAllHttpScopedObjects()</code> on the <code>EndRequest</code> event.</p> <p>This works great for MVC controllers until a service requiring a database connection is injected into a SignalR hub, which keeps a persistent HTTP connection open for each client and eventually saturates the connection pool.</p> <p>If I scope <code>IDbConnection</code> to a singleton, only one connection is ever opened per-application and the pool doesn't saturate, but this is <a href="https://stackoverflow.com/a/1557614/198927">a bad idea</a> in case the connection is ever locked or times out.</p> <p>So maybe there is a way to customise the scope of database connections for my SignalR hubs? I tried resolving a service instance in each Hub method, but this still instantiates a database connection at the HttpContext scope and keeps it open for the duration of the calling client's hub connection.</p> <p>How should I manage the lifetime of database connections with StructureMap in an HTTP-scoped context when there are persistent HTTP connections around?</p> <h1>Example Code</h1> <h2>Typical Service</h2> <pre><code>public class MyService { private IDbConnection _con; public MyService(IDbConnection con) { _con = con; } public IEnumerable&lt;string&gt; GetStuff() { return _con.Select&lt;string&gt;("SELECT someString FROM SomeTable").ToList(); } } </code></pre> <h2>Typical SignalR Hub</h2> <pre><code>public class MyHub : Hub { private MyService _service; public MyHub(MyService service) { _service = service; // Oh Noes! This will open a database connection // for each Client because of HttpContext scope } public Task AddMessage() { var result = _service.GetStuff(); // ... } } </code></pre> <h2>StructureMap Configuration</h2> <pre><code>For&lt;IDbConnection&gt;() .HybridHttpOrThreadLocalScoped() .Use(() =&gt; BaseController.GetOpenConnection(MyConnectionString)); </code></pre> <h2>Global.asax.cs</h2> <pre><code>public class GlobalApplication : System.Web.HttpApplication { public GlobalApplication() { EndRequest += delegate { ObjectFactory.ReleaseAndDisposeAllHttpScopedObjects(); }; } // ... } </code></pre>
 

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