using System; using System.Threading; namespace Renci.SshNet.Common { public abstract class AsyncResult : IAsyncResult { private const int StatePending = 0; private const int StateCompletedSynchronously = 1; private const int StateCompletedAsynchronously = 2; private readonly AsyncCallback _asyncCallback; private readonly object _asyncState; private int _completedState; private ManualResetEvent _asyncWaitHandle; private Exception _exception; public bool EndInvokeCalled { get; set; } public object AsyncState => _asyncState; public bool CompletedSynchronously => _completedState == 1; public WaitHandle AsyncWaitHandle { get { if (_asyncWaitHandle == null) { bool isCompleted = IsCompleted; ManualResetEvent manualResetEvent = new ManualResetEvent(isCompleted); if (Interlocked.CompareExchange(ref _asyncWaitHandle, manualResetEvent, null) != null) manualResetEvent.Dispose(); else if (!isCompleted && IsCompleted) { _asyncWaitHandle.Set(); } } return _asyncWaitHandle; } } public bool IsCompleted => _completedState != 0; protected AsyncResult(AsyncCallback asyncCallback, object state) { _asyncCallback = asyncCallback; _asyncState = state; } public void SetAsCompleted(Exception exception, bool completedSynchronously) { _exception = exception; if (Interlocked.Exchange(ref _completedState, completedSynchronously ? 1 : 2) != 0) throw new InvalidOperationException("You can set a result only once"); _asyncWaitHandle?.Set(); _asyncCallback?.Invoke(this); } internal void EndInvoke() { if (!IsCompleted) { AsyncWaitHandle.WaitOne(); _asyncWaitHandle = null; AsyncWaitHandle.Dispose(); } EndInvokeCalled = true; if (_exception != null) throw _exception; } } }