From 28b87e4d9c60b49d46b03a19b7b83e23e222087a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Mon, 22 Aug 2022 01:02:34 +0200
Subject: Handle exceptions in fetching thread.

---
 c/main.cpp | 35 ++++++-----------------------------
 1 file changed, 6 insertions(+), 29 deletions(-)

(limited to 'c/main.cpp')

diff --git a/c/main.cpp b/c/main.cpp
index d6e3027..73a89d4 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -24,7 +24,7 @@
 
 /* Exit gracefully on uncaught exception. */
 static void OnTerminate() noexcept;
-static auto unused = std::set_terminate(OnTerminate);
+static auto UNUSED = std::set_terminate(OnTerminate);
 
 /* main.cpp defines all global (non-template) variables used in the
  * program. `extern' is used to access them from other files, when
@@ -81,29 +81,7 @@ static void UpdateTheme();
 
 void OnTerminate() noexcept
 {
-	const wchar_t* what = L"an exception";
-	WcharPtr why;
-
-	try {
-		std::rethrow_exception(std::current_exception());
-        } catch (const term_t& t) {
-		what = L"a Prolog exception";
-		try { why = PlString(t); } catch (...) {}
-	} catch (const Win32Error& e) {
-		what = L"a Windows error";
-		try { why = WcharPtr::Copy(e.What()); } catch (...) {}
-	} catch (const std::exception& e) {
-		try { why = WcharPtr::FromNarrow(e.what()); } catch (...) {}
-	} catch (...) {}
-
-	wchar_t msg[256] = {0};
-	if (why)
-		Swprintf(msg, L"Episode Browser was terminated due to %s: %s",
-		    what, static_cast<wchar_t*>(why));
-	else
-		Swprintf(msg, L"Episode Browser was terminated due to %s.", what);
-
-	MessageBox(g_hWnd, msg, L"Fatal Error", MB_ICONERROR);
+	ShowException(L"Episode Browser was terminated due to %s: %s", L"Fatal Error", MB_ICONERROR);
 	_Exit(1);
 }
 
@@ -402,7 +380,7 @@ void HandleMainMenu(const HWND hWnd, const WORD command)
 
 	case IDM_FILE_FETCH_DATA:
 	    {
-		WaitFor(FetchData);
+		WaitFor(WaitFetchData);
 		break;
 	    }
 
@@ -456,13 +434,11 @@ void HandleMainMenu(const HWND hWnd, const WORD command)
 
 void WaitFor(void (*f)(bool*))
 {
-	/* WaitFor uses a thread on the Prolog side to execute a
-	 * predicate asynchronously. */
-
 	static bool bActive = false;
 	static bool bDone = false;
 	static UINT_PTR iTimer;
 
+	/* Ensure that only a single thread is waited on. */
 	if (bActive) {
 		if (EBMessageBox(L"Another task is active. "
 		    L"Do you want to cancel the existing task and start a new one?",
@@ -476,7 +452,6 @@ void WaitFor(void (*f)(bool*))
 
 	/* The timer procedure animates an ellipsis in the status bar
 	 * while the thread is running. */
-
 	static auto proc = [](HWND, UINT, UINT_PTR, DWORD) -> void
 	{
 		static int i = 0;
@@ -494,6 +469,8 @@ void WaitFor(void (*f)(bool*))
 		}
 	};
 
+	/* The waited-on function signals its completion by setting a
+	 * shared boolean value to true. */
 	bDone = false;
 	bActive = true;
 	std::thread{f, &bDone}.detach();
-- 
cgit v1.2.3