Try closing gracefully before terminating process

Use a Microsoft recommended way of process termination for the project
process run from the editor. This allows loaded DLLs to receive and handle
DLL_PROCESS_DETACH notification and cleanup any global state before the
process actually exits.

core/os/os.h

@@ -254,7 +254,7 @@ public:
 
 	virtual String get_executable_path() const;
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false) = 0;
-	virtual Error kill(const ProcessID &p_pid) = 0;
+	virtual Error kill(const ProcessID &p_pid, const int p_max_wait_msec = -1) = 0;
 	virtual int get_process_id() const;
 
 	virtual Error shell_open(String p_uri);

drivers/unix/os_unix.cpp

@@ -329,7 +329,7 @@ Error OS_Unix::execute(const String &p_path, const List<String> &p_arguments, bo
 	return OK;
 }
 
-Error OS_Unix::kill(const ProcessID &p_pid) {
+Error OS_Unix::kill(const ProcessID &p_pid, const int p_max_wait_msec) {
 
 	int ret = ::kill(p_pid, SIGKILL);
 	if (!ret) {

drivers/unix/os_unix.h

@@ -91,7 +91,7 @@ public:
 	virtual uint64_t get_ticks_usec() const;
 
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false);
-	virtual Error kill(const ProcessID &p_pid);
+	virtual Error kill(const ProcessID &p_pid, const int p_max_wait_msec = -1);
 	virtual int get_process_id() const;
 
 	virtual bool has_environment(const String &p_var) const;

editor/editor_run.cpp

@@ -181,8 +181,8 @@ Error EditorRun::run(const String &p_scene, const String p_custom_args, const Li
 void EditorRun::stop() {
 
 	if (status != STATUS_STOP && pid != 0) {
-
-		OS::get_singleton()->kill(pid);
+		const int max_wait_msec = GLOBAL_DEF("editor/stop_max_wait_msec", 10000);
+		OS::get_singleton()->kill(pid, max_wait_msec);
 	}
 
 	status = STATUS_STOP;

platform/windows/os_windows.cpp

@@ -190,6 +190,28 @@ BOOL WINAPI HandlerRoutine(_In_ DWORD dwCtrlType) {
 	}
 }
 
+BOOL CALLBACK _CloseWindowsEnum(HWND hWnd, LPARAM lParam) {
+	DWORD dwID;
+
+	GetWindowThreadProcessId(hWnd, &dwID);
+
+	if (dwID == (DWORD)lParam) {
+		PostMessage(hWnd, WM_CLOSE, 0, 0);
+	}
+
+	return TRUE;
+}
+
+bool _close_gracefully(const PROCESS_INFORMATION &pi, const DWORD dwStopWaitMsec) {
+	if (!EnumWindows(_CloseWindowsEnum, pi.dwProcessId))
+		return false;
+
+	if (WaitForSingleObject(pi.hProcess, dwStopWaitMsec) != WAIT_OBJECT_0)
+		return false;
+
+	return true;
+}
+
 void OS_Windows::initialize_debugging() {
 
 	SetConsoleCtrlHandler(HandlerRoutine, TRUE);
@@ -2322,20 +2344,26 @@ Error OS_Windows::execute(const String &p_path, const List<String> &p_arguments,
 	return OK;
 };
 
-Error OS_Windows::kill(const ProcessID &p_pid) {
-
+Error OS_Windows::kill(const ProcessID &p_pid, const int p_max_wait_msec) {
 	ERR_FAIL_COND_V(!process_map->has(p_pid), FAILED);
 
 	const PROCESS_INFORMATION pi = (*process_map)[p_pid].pi;
 	process_map->erase(p_pid);
 
-	const int ret = TerminateProcess(pi.hProcess, 0);
+	Error result;
+
+	if (p_max_wait_msec != -1 && _close_gracefully(pi, p_max_wait_msec)) {
+		result = OK;
+	} else {
+		const int ret = TerminateProcess(pi.hProcess, 0);
+		result = ret != 0 ? OK : FAILED;
+	}
 
 	CloseHandle(pi.hProcess);
 	CloseHandle(pi.hThread);
 
-	return ret != 0 ? OK : FAILED;
-};
+	return result;
+}
 
 int OS_Windows::get_process_id() const {
 	return _getpid();

platform/windows/os_windows.h

@@ -258,7 +258,7 @@ public:
 	virtual uint64_t get_ticks_usec() const;
 
 	virtual Error execute(const String &p_path, const List<String> &p_arguments, bool p_blocking, ProcessID *r_child_id = NULL, String *r_pipe = NULL, int *r_exitcode = NULL, bool read_stderr = false);
-	virtual Error kill(const ProcessID &p_pid);
+	virtual Error kill(const ProcessID &p_pid, const int p_stop_max_wait_msec = -1);
 	virtual int get_process_id() const;
 
 	virtual bool has_environment(const String &p_var) const;