1 files changed, 48 insertions, 0 deletions
diff --git a/src/zenutil/process/exitwatcher.h b/src/zenutil/process/exitwatcher.h
new file mode 100644
index 000000000..24906d7d0
--- /dev/null
+++ b/src/zenutil/process/exitwatcher.h
@@ -0,0 +1,48 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#pragma once
+
+#include <zencore/process.h>
+#include <zencore/zencore.h>
+
+#include <functional>
+#include <memory>
+
+namespace asio {
+class io_context;
+}
+
+namespace zen {
+
+/// Async process exit watcher.
+///
+/// Uses platform-specific mechanisms for scalable, non-polling exit detection:
+///   Linux:   pidfd_open() + asio::posix::stream_descriptor
+///   Windows: asio::windows::object_handle
+///   macOS:   kqueue EVFILT_PROC/NOTE_EXIT + asio::posix::stream_descriptor
+///
+/// The callback is invoked exactly once when the process exits, posted to the
+/// io_context. Call Cancel() to suppress the callback.
+class ProcessExitWatcher
+{
+public:
+	explicit ProcessExitWatcher(asio::io_context& IoContext);
+	~ProcessExitWatcher();
+
+	ProcessExitWatcher(const ProcessExitWatcher&) = delete;
+	ProcessExitWatcher& operator=(const ProcessExitWatcher&) = delete;
+
+	/// Begin watching the given process. The callback is posted to the io_context
+	/// when the process exits. Only one Watch() may be active at a time.
+	void Watch(const ProcessHandle& Handle, std::function<void(int ExitCode)> OnExit);
+
+	/// Cancel any outstanding watch. The callback will not be invoked after this
+	/// returns. Safe to call if no watch is active.
+	void Cancel();
+
+private:
+	struct Impl;
+	std::unique_ptr<Impl> m_Impl;
+};
+
+}  // namespace zen