1 files changed, 51 insertions, 0 deletions

diff --git a/Rx/NET/Source/System.Reactive.Linq/Reactive/Internal/Producer.cs b/Rx/NET/Source/System.Reactive.Linq/Reactive/Internal/Producer.cs
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index 0000000..85ed55f
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+++ b/Rx/NET/Source/System.Reactive.Linq/Reactive/Internal/Producer.cs
@@ -0,0 +1,51 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+#if !NO_PERF
+using System.Reactive.Concurrency;
+using System.Reactive.Disposables;
+
+namespace System.Reactive
+{
+    /// <summary>
+    /// Base class for implementation of query operators, providing performance benefits over the use of <see cref="System.Reactive.Linq.Observable.Create">Observable.Create</see>.
+    /// </summary>
+    /// <typeparam name="TSource">Type of the resulting sequence's elements.</typeparam>
+    abstract class Producer<TSource> : IObservable<TSource>
+    {
+        /// <summary>
+        /// Publicly visible Subscribe method.
+        /// </summary>
+        /// <param name="observer">Observer to send notifications on. The implementation of a producer must ensure the correct message grammar on the observer.</param>
+        /// <returns>IDisposable to cancel the subscription. This causes the underlying sink to be notified of unsubscription, causing it to prevent further messages from being sent to the observer.</returns>
+        public IDisposable Subscribe(IObserver<TSource> observer)
+        {
+            if (observer == null)
+                throw new ArgumentNullException("observer");
+
+            var sink = new SingleAssignmentDisposable();
+            var subscription = new SingleAssignmentDisposable();
+
+            if (CurrentThreadScheduler.Instance.ScheduleRequired)
+            {
+                CurrentThreadScheduler.Instance.Schedule(this, (_, me) => subscription.Disposable = me.Run(observer, subscription, s => sink.Disposable = s));
+            }
+            else
+            {
+                subscription.Disposable = this.Run(observer, subscription, s => sink.Disposable = s);
+            }
+
+            return new CompositeDisposable(2) { sink, subscription };
+        }
+
+        /// <summary>
+        /// Core implementation of the query operator, called upon a new subscription to the producer object.
+        /// </summary>
+        /// <param name="observer">Observer to send notifications on. The implementation of a producer must ensure the correct message grammar on the observer.</param>
+        /// <param name="cancel">The subscription disposable object returned from the Run call, passed in such that it can be forwarded to the sink, allowing it to dispose the subscription upon sending a final message (or prematurely for other reasons).</param>
+        /// <param name="setSink">Callback to communicate the sink object to the subscriber, allowing consumers to tunnel a Dispose call into the sink, which can stop the processing.</param>
+        /// <returns>Disposable representing all the resources and/or subscriptions the operator uses to process events.</returns>
+        /// <remarks>The <paramref name="observer">observer</paramref> passed in to this method is not protected using auto-detach behavior upon an OnError or OnCompleted call. The implementation must ensure proper resource disposal and enforce the message grammar.</remarks>
+        protected abstract IDisposable Run(IObserver<TSource> observer, IDisposable cancel, Action<IDisposable> setSink);
+    }
+}
+#endif
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