making project compile

Author: aishwaryabh

src/Cli/func/Helpers/FileLockHelper.cs

@@ -0,0 +1,52 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See LICENSE in the project root for license information.
+
+namespace Azure.Functions.Cli.Helpers
+{
+    public static class FileLockHelper
+    {
+        private const string DefaultLockFileName = "func.lock";
+        private static readonly string _templatesLockFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".azurefunctions");
+
+        public static async Task<T> WithFileLockAsync<T>(string lockFileName, Func<Task<T>> action)
+        {
+            lockFileName ??= DefaultLockFileName;
+            var lockFile = Path.Combine(_templatesLockFilePath, lockFileName);
+
+            for (int attempt = 0; attempt < 20; attempt++)
+            {
+                FileStream stream = null;
+                try
+                {
+                    stream = new FileStream(
+                        lockFile,
+                        FileMode.OpenOrCreate,
+                        FileAccess.ReadWrite,
+                        FileShare.Delete);
+
+                    return await action();
+                }
+                catch (IOException)
+                {
+                    stream?.Dispose();
+                    await Task.Delay(1000);
+                }
+                finally
+                {
+                    stream?.Dispose();
+                }
+            }
+
+            throw new IOException($"Could not acquire file lock on {lockFile} after multiple attempts.");
+        }
+
+        public static Task WithFileLockAsync(string lockFileName, Func<Task> action)
+        {
+            return WithFileLockAsync(lockFileName, async () =>
+            {
+                await action();
+                return true;
+            });
+        }
+    }
+}