Merge pull request #535 from GridProtectionAlliance/XDA-83

XDA-83 Automatically enumerate a directory where the 'too many changes' error occurs

Author: clackner-gpa

Source/Libraries/GSF.Core.Shared/GSF.Core.Shared.projitems

@@ -152,6 +152,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Threading\StateMachine.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Threading\SharedTimer.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Threading\SynchronizedOperationBase.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Threading\SynchronizedTask.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Threading\TaskSynchronizedOperation.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Threading\ThreadContainerBase.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Threading\ThreadContainerDedicated.cs" />

Source/Libraries/GSF.Core.Shared/Threading/SynchronizedTask.cs

@@ -0,0 +1,173 @@
+//******************************************************************************************************
+//  SynchronizedTask.cs - Gbtc
+//
+//  Copyright © 2026, Grid Protection Alliance.  All Rights Reserved.
+//
+//  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See
+//  the NOTICE file distributed with this work for additional information regarding copyright ownership.
+//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may not use this
+//  file except in compliance with the License. You may obtain a copy of the License at:
+//
+//      http://opensource.org/licenses/MIT
+//
+//  Unless agreed to in writing, the subject software distributed under the License is distributed on an
+//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the
+//  License for the specific language governing permissions and limitations.
+//
+//  Code Modification History:
+//  ----------------------------------------------------------------------------------------------------
+//  05/19/2026 - Stephen C. Wills
+//       Generated original version of source code.
+//
+//******************************************************************************************************
+
+using System;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+namespace GSF.Core.Threading
+{
+    /// <summary>
+    /// Represents a task that cannot run while it is already in progress.
+    /// </summary>
+    /// <typeparam name="T">The type of object returned by the task when it executes.</typeparam>
+    public class SynchronizedTask<T>
+    {
+        /// <summary>
+        /// Creates a new instance of the <see cref="SynchronizedTask{T}"/> class.
+        /// </summary>
+        /// <param name="callback">The callback to be executed when the task runs</param>
+        /// <exception cref="ArgumentNullException"><paramref name="callback"/> is null</exception>
+        public SynchronizedTask(Func<Task<T>> callback)
+        {
+            if (callback is null)
+                throw new ArgumentNullException(nameof(callback));
+
+            Callback = callback;
+        }
+
+        /// <summary>
+        /// Gets a value to indicate whether the synchronized
+        /// task is currently executing its callback.
+        /// </summary>
+        public bool IsRunning
+        {
+            get
+            {
+                lock (TaskLock)
+                    return RunningTask is not null;
+            }
+        }
+
+        /// <summary>
+        /// Gets a value to indiate whether the synchronized task
+        /// has an additional callback that is pending execution after
+        /// the currently running task has completed.
+        /// </summary>
+        public bool IsPending
+        {
+            get
+            {
+                lock (TaskLock)
+                    return PendingTask is not null;
+            }
+        }
+
+        private Func<Task<T>> Callback { get; }
+
+        private object TaskLock { get; } = new();
+        private Task<T> LastCompletedTask { get; set; }
+        private Task<T> RunningTask { get; set; }
+        private Task<T> PendingTask { get; set; }
+
+        /// <summary>
+        /// Executes the callback on another thread or marks the
+        /// task as pending if the callback is already running.
+        /// </summary>
+        /// <returns>A task that completes when the callback completes.</returns>
+        public Task<T> RunAsync()
+        {
+            lock (TaskLock)
+            {
+                if (RunningTask is null)
+                {
+                    RunningTask = Task.Run(ExecuteCallback);
+                    return RunningTask;
+                }
+
+                if (PendingTask is null)
+                {
+                    Task<T> runningTask = RunningTask;
+
+                    PendingTask = Task.Run(async () =>
+                    {
+                        await runningTask.ConfigureAwait(false);
+                        return await ExecuteCallback().ConfigureAwait(false);
+                    });
+                }
+
+                return PendingTask;
+            }
+        }
+
+        /// <summary>
+        /// Returns a task that completes when the currently
+        /// running and pending tasks are both complete.
+        /// </summary>
+        /// <returns>A task instance.</returns>
+        public async Task FlushAsync()
+        {
+            Task pendingTask;
+
+            lock (TaskLock)
+                pendingTask = PendingTask ?? RunningTask ?? Task.CompletedTask;
+
+            try { await pendingTask; }
+            catch { /* Ignore errors when flushing */ }
+        }
+
+        /// <summary>
+        /// Returns an awaiter used to await the most recently completed callback.
+        /// </summary>
+        /// <returns>An awaiter instance.</returns>
+        public TaskAwaiter<T> GetAwaiter()
+        {
+            lock (TaskLock)
+            {
+                Task<T> task = LastCompletedTask ?? RunningTask ?? RunAsync();
+                return task.GetAwaiter();
+            }
+        }
+
+        /// <summary>
+        /// Configures an awaiter used to await the most recently completed callback.
+        /// </summary>
+        /// <param name="continueOnCapturedContext">true to attempt to marshal the continuation back to the original context captured; otherwise, false</param>
+        /// <returns>An object used to await the most recently completed callback.</returns>
+        public ConfiguredTaskAwaitable<T> ConfigureAwait(bool continueOnCapturedContext)
+        {
+            lock (TaskLock)
+            {
+                Task<T> task = LastCompletedTask ?? RunningTask ?? RunAsync();
+                return task.ConfigureAwait(continueOnCapturedContext);
+            }
+        }
+
+        private async Task<T> ExecuteCallback()
+        {
+            try
+            {
+                return await Callback().ConfigureAwait(false);
+            }
+            finally
+            {
+                lock (TaskLock)
+                {
+                    LastCompletedTask = RunningTask;
+                    RunningTask = PendingTask;
+                    PendingTask = null;
+                }
+            }
+        }
+    }
+}