Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/WebSocketTransitionState.cs

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+//------------------------------------------------------------------------------
+// <copyright file="WebSocketTransitionState.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Web {
+
+    // Represents the transition state of a WebSocket request.
+    // Any state can be a terminal state, but if a state transition does take place it will go in the
+    // order Inactive -> AcceptWebSocketRequestCalled -> TransitionStarted -> TransitionCompleted.
+
+    internal enum WebSocketTransitionState : byte {
+
+        // This is not a WebSocket request, or if it is HttpContext.AcceptWebSocketRequest() hasn't yet been called.
+        Inactive = 0,
+
+        // HttpContext.AcceptWebSocketRequest() has been called, but we haven't yet started the transition.
+        // This means that the request handler or ASP.NET modules may still be running.
+        AcceptWebSocketRequestCalled,
+
+        // We have started the transition, e.g. we're in the process of tearing down request state and releasing
+        // objects (like HttpApplication instances) back into their respective pools. The handshake with the client
+        // will also be performed during this time. Asynchronous module-level events (like SendResponse) should
+        // not be fired after this point.
+        TransitionStarted,
+
+        // We have completed the transition, e.g. the handshake is completed and we have an active connection
+        // with the client. The callback the developer passed to HttpContext.AcceptWebSocketRequest() is executing.
+        TransitionCompleted
+
+    }
+}