Merge branch 'master' into nullable4

1 files changed, 80 insertions, 0 deletions

diff --git a/MediaBrowser.Common/Extensions/ProcessExtensions.cs b/MediaBrowser.Common/Extensions/ProcessExtensions.cs
new file mode 100644
index 000000000..c74787122
--- /dev/null
+++ b/MediaBrowser.Common/Extensions/ProcessExtensions.cs
@@ -0,0 +1,80 @@
+using System;
+using System.Diagnostics;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace MediaBrowser.Common.Extensions
+{
+    /// <summary>
+    /// Extension methods for <see cref="Process"/>.
+    /// </summary>
+    public static class ProcessExtensions
+    {
+        /// <summary>
+        /// Asynchronously wait for the process to exit.
+        /// </summary>
+        /// <param name="process">The process to wait for.</param>
+        /// <param name="timeout">The duration to wait before cancelling waiting for the task.</param>
+        /// <returns>True if the task exited normally, false if the timeout elapsed before the process exited.</returns>
+        /// <exception cref="InvalidOperationException">If <see cref="Process.EnableRaisingEvents"/> is not set to true for the process.</exception>
+        public static async Task<bool> WaitForExitAsync(this Process process, TimeSpan timeout)
+        {
+            using (var cancelTokenSource = new CancellationTokenSource(timeout))
+            {
+                return await WaitForExitAsync(process, cancelTokenSource.Token).ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Asynchronously wait for the process to exit.
+        /// </summary>
+        /// <param name="process">The process to wait for.</param>
+        /// <param name="cancelToken">A <see cref="CancellationToken"/> to observe while waiting for the process to exit.</param>
+        /// <returns>True if the task exited normally, false if cancelled before the process exited.</returns>
+        public static async Task<bool> WaitForExitAsync(this Process process, CancellationToken cancelToken)
+        {
+            if (!process.EnableRaisingEvents)
+            {
+                throw new InvalidOperationException("EnableRisingEvents must be enabled to async wait for a task to exit.");
+            }
+
+            // Add an event handler for the process exit event
+            var tcs = new TaskCompletionSource<bool>();
+            process.Exited += (sender, args) => tcs.TrySetResult(true);
+
+            // Return immediately if the process has already exited
+            if (process.HasExitedSafe())
+            {
+                return true;
+            }
+
+            // Register with the cancellation token then await
+            using (var cancelRegistration = cancelToken.Register(() => tcs.TrySetResult(process.HasExitedSafe())))
+            {
+                return await tcs.Task.ConfigureAwait(false);
+            }
+        }
+
+        /// <summary>
+        /// Gets a value indicating whether the associated process has been terminated using
+        /// <see cref="Process.HasExited"/>. This is safe to call even if there is no operating system process
+        /// associated with the <see cref="Process"/>.
+        /// </summary>
+        /// <param name="process">The process to check the exit status for.</param>
+        /// <returns>
+        /// True if the operating system process referenced by the <see cref="Process"/> component has
+        /// terminated, or if there is no associated operating system process; otherwise, false.
+        /// </returns>
+        private static bool HasExitedSafe(this Process process)
+        {
+            try
+            {
+                return process.HasExited;
+            }
+            catch (InvalidOperationException)
+            {
+                return true;
+            }
+        }
+    }
+}