Add ModelContextProtocol.Core package (#428)

src/ModelContextProtocol.Core/ProcessHelper.cs

@@ -0,0 +1,130 @@
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace ModelContextProtocol;
+
+/// <summary>
+/// Helper class for working with processes.
+/// </summary>
+internal static class ProcessHelper
+{
+    private static readonly bool _isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+    private static readonly TimeSpan _defaultTimeout = TimeSpan.FromSeconds(30);
+
+    /// <summary>
+    /// Kills a process and all of its child processes (entire process tree).
+    /// </summary>
+    /// <param name="process">The process to terminate along with its child processes.</param>
+    /// <remarks>
+    /// This method uses a default timeout of 30 seconds when waiting for processes to exit.
+    /// On Windows, this uses the "taskkill" command with the /T flag.
+    /// On non-Windows platforms, it recursively identifies and terminates child processes.
+    /// </remarks>
+    public static void KillTree(this Process process) => process.KillTree(_defaultTimeout);
+
+    /// <summary>
+    /// Kills a process and all of its child processes (entire process tree) with a specified timeout.
+    /// </summary>
+    /// <param name="process">The process to terminate along with its child processes.</param>
+    /// <param name="timeout">The maximum time to wait for the processes to exit.</param>
+    /// <remarks>
+    /// On Windows, this uses the "taskkill" command with the /T flag to terminate the process tree.
+    /// On non-Windows platforms, it recursively identifies and terminates child processes.
+    /// The method waits for the specified timeout for processes to exit before continuing.
+    /// This is particularly useful for applications that spawn child processes (like Node.js)
+    /// that wouldn't be terminated automatically when the parent process exits.
+    /// </remarks>
+    public static void KillTree(this Process process, TimeSpan timeout)
+    {
+        var pid = process.Id;
+        if (_isWindows)
+        {
+            RunProcessAndWaitForExit(
+                "taskkill",
+                $"/T /F /PID {pid}",
+                timeout,
+                out var _);
+        }
+        else
+        {
+            var children = new HashSet<int>();
+            GetAllChildIdsUnix(pid, children, timeout);
+            foreach (var childId in children)
+            {
+                KillProcessUnix(childId, timeout);
+            }
+            KillProcessUnix(pid, timeout);
+        }
+
+        // wait until the process finishes exiting/getting killed. 
+        // We don't want to wait forever here because the task is already supposed to be dieing, we just want to give it long enough
+        // to try and flush what it can and stop. If it cannot do that in a reasonable time frame then we will just ignore it.
+        process.WaitForExit((int)timeout.TotalMilliseconds);
+    }
+
+    private static void GetAllChildIdsUnix(int parentId, ISet<int> children, TimeSpan timeout)
+    {
+        var exitcode = RunProcessAndWaitForExit(
+            "pgrep",
+            $"-P {parentId}",
+            timeout,
+            out var stdout);
+
+        if (exitcode == 0 && !string.IsNullOrEmpty(stdout))
+        {
+            using var reader = new StringReader(stdout);
+            while (true)
+            {
+                var text = reader.ReadLine();
+                if (text == null)
+                    return;
+
+                if (int.TryParse(text, out var id))
+                {
+                    children.Add(id);
+                    // Recursively get the children
+                    GetAllChildIdsUnix(id, children, timeout);
+                }
+            }
+        }
+    }
+
+    private static void KillProcessUnix(int processId, TimeSpan timeout)
+    {
+        RunProcessAndWaitForExit(
+            "kill",
+            $"-TERM {processId}",
+            timeout,
+            out var _);
+    }
+
+    private static int RunProcessAndWaitForExit(string fileName, string arguments, TimeSpan timeout, out string? stdout)
+    {
+        var startInfo = new ProcessStartInfo
+        {
+            FileName = fileName,
+            Arguments = arguments,
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            UseShellExecute = false,
+            CreateNoWindow = true,
+        };
+
+        stdout = null;
+
+        var process = Process.Start(startInfo);
+        if (process == null)
+            return -1;
+
+        if (process.WaitForExit((int)timeout.TotalMilliseconds))
+        {
+            stdout = process.StandardOutput.ReadToEnd();
+        }
+        else
+        {
+            process.Kill();
+        }
+
+        return process.ExitCode;
+    }
+}