65 lines
1.7 KiB
C#
65 lines
1.7 KiB
C#
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#if CSHARP_7_OR_LATER || (UNITY_2018_3_OR_NEWER && (NET_STANDARD_2_0 || NET_4_6))
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#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
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using System;
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using System.Threading;
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namespace UniRx.Async
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{
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public class AsyncLazy<T>
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{
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Func<UniTask<T>> valueFactory;
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UniTask<T> target;
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object syncLock;
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bool initialized;
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public AsyncLazy(Func<UniTask<T>> valueFactory)
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{
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this.valueFactory = valueFactory;
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this.target = default;
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this.syncLock = new object();
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this.initialized = false;
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}
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internal AsyncLazy(UniTask<T> value)
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{
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this.valueFactory = null;
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this.target = value;
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this.syncLock = null;
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this.initialized = true;
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}
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public UniTask<T> Task => EnsureInitialized();
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public UniTask<T>.Awaiter GetAwaiter() => EnsureInitialized().GetAwaiter();
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UniTask<T> EnsureInitialized()
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{
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if (Volatile.Read(ref initialized))
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{
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return target;
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}
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return EnsureInitializedCore();
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}
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UniTask<T> EnsureInitializedCore()
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{
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lock (syncLock)
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{
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if (!Volatile.Read(ref initialized))
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{
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var f = Interlocked.Exchange(ref valueFactory, null);
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if (f != null)
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{
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target = f().Preserve(); // with preserve(allow multiple await).
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Volatile.Write(ref initialized, true);
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}
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}
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}
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return target;
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}
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}
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}
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#endif
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