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POIs there a common pattern for initializing object on a background thread?
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  1. POIs there a common pattern for initializing object on a background thread?
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    copied!<p>I have an object that takes a long time to be initialized. Therefore I the capability to Start Initializing on application startup. Any subsequent calls to methods on the class we need to have a delay mechanism that waits for the class to finish initialization. </p> <p>I have a couple of potential solutions however I am not entirely satisfied with either of them. The first uses Task.Delay in a while loop and the second uses SemaphoreSlim but involves some unnecessary blocking. I feel this must be a fairly common requirement, can anybody provide some advice on how to best manage this? </p> <p>Oh btw, this is a Metro application so we have limited API's</p> <p>Here is the pseudocode:</p> <pre><code>public class ExposeSomeInterestingItems { private InitialisationState _initialised; private readonly SemaphoreSlim _waiter = new SemaphoreSlim(0); public async Task StartInitialize() { if (_initialised == InitialisationState.Initialised) { throw new InvalidOperationException( "Attempted to initialise ActiveTrackDown" + "loads when it is already initialized"); } _initialised = InitialisationState.StartedInitialisation; new TaskFactory().StartNew(async () =&gt; { // This takes some time to load this._interestingItems = InterestingItemsLoader.LoadItems(); _waiter.Release(); _initialised = InitialisationState.Initialised; }); } public InterestingItem GetItem(string id) { DelayUntilLoaded(); DelayUntilLoadedAlternative(); } private async Task DelayUntilLoaded() { if (_initialised == InitialisationState.NotInitialised) { throw new InvalidOperationException("Error " + "occurred attempting to access details on " + "ActiveTrackDownloads before calling initialise"); } while (true) { if (_initialised == InitialisationState.Initialised) { return; } await Task.Delay(300); } } private async Task DelayUntilLoadedAlternative() { if (_initialised == InitialisationState.NotInitialised) { throw new InvalidOperationException( "Error occurred attempting to access details " + "on ActiveTrackDownloads before calling initialise"); } try { await _waiter.WaitAsync(); } finally { _waiter.Release(); } } } </code></pre>
 

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