System.IO.FileSystemWatcher.WaitForChanged C# (CSharp) Method

        public WaitForChangedResult WaitForChanged(WatcherChangeTypes changeType, int timeout)
        {
            // The full framework implementation doesn't do any argument validation, so
            // none is done here, either.

            var tcs = new TaskCompletionSource<WaitForChangedResult>();
            FileSystemEventHandler fseh = null;
            RenamedEventHandler reh = null;

            // Register the event handlers based on what events are desired.  The full framework
            // doesn't register for the Error event, so this doesn't either.
            if ((changeType & (WatcherChangeTypes.Created | WatcherChangeTypes.Deleted | WatcherChangeTypes.Changed)) != 0)
            {
                fseh = (s, e) =>
                {
                    if ((e.ChangeType & changeType) != 0)
                    {
                        tcs.TrySetResult(new WaitForChangedResult(e.ChangeType, e.Name, oldName: null, timedOut: false));
                    }
                };
                if ((changeType & WatcherChangeTypes.Created) != 0) Created += fseh;
                if ((changeType & WatcherChangeTypes.Deleted) != 0) Deleted += fseh;
                if ((changeType & WatcherChangeTypes.Changed) != 0) Changed += fseh;
            }
            if ((changeType & WatcherChangeTypes.Renamed) != 0)
            {
                reh = (s, e) =>
                {
                    if ((e.ChangeType & changeType) != 0)
                    {
                        tcs.TrySetResult(new WaitForChangedResult(e.ChangeType, e.Name, e.OldName, timedOut: false));
                    }
                };
                Renamed += reh;
            }
            try
            {
                // Enable the FSW if it wasn't already.
                bool wasEnabled = EnableRaisingEvents;
                if (!wasEnabled)
                {
                    EnableRaisingEvents = true;
                }

                // Block until an appropriate event arrives or until we timeout.
                Debug.Assert(EnableRaisingEvents, "Expected EnableRaisingEvents to be true");
                tcs.Task.Wait(timeout);

                // Reset the enabled state to what it was.
                EnableRaisingEvents = wasEnabled;
            }
            finally
            {
                // Unregister the event handlers.
                if (reh != null)
                {
                    Renamed -= reh;
                }
                if (fseh != null)
                {
                    if ((changeType & WatcherChangeTypes.Changed) != 0) Changed -= fseh;
                    if ((changeType & WatcherChangeTypes.Deleted) != 0) Deleted -= fseh;
                    if ((changeType & WatcherChangeTypes.Created) != 0) Created -= fseh;
                }
            }

            // Return the results.
            return tcs.Task.Status == TaskStatus.RanToCompletion ?
                tcs.Task.Result :
                WaitForChangedResult.TimedOutResult;
        }

        private static void ReadFromFile()
        {
            long offset = 0;

            FileSystemWatcher fsw = new FileSystemWatcher
            {
                Path = "C:\\Share\\1",
                Filter = "INDICATE_REPORT.txt"
            };

            FileStream file = File.Open(
                FilePathWip21,
                FileMode.Open,
                FileAccess.Read,
                FileShare.Write);

            StreamReader reader = new StreamReader(file);
            while (true)
            {
                fsw.WaitForChanged(WatcherChangeTypes.Changed);

                file.Seek(offset, SeekOrigin.Begin);
                if (!reader.EndOfStream)
                {
                    do
                    {
                        Console.WriteLine(reader.ReadLine());
                    } while (!reader.EndOfStream);

                    offset = file.Position;
                }
            }
        }