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Fix PinMAME busy-wait freeze on Controller.Stop() (dispose() hang)

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Controller::Stop() (real desktop vpinball code, unmodified until now)
busy-waits for PinmameIsRunning() to clear after calling PinmameStop(),
in a sleep loop meant for a real OS thread to notice the quit flag and
finish stopping on its own. Under Emscripten there is no such thread -
PinmameStop() there only sets the quit flag - so the loop spun forever
on the single available thread, with nothing left to ever clear it.

This fires from Player::~Player()'s GameEvents_Exit script event
(controller.vbs's default Exit handler calls Controller.Stop), which
runs synchronously inside dispose() - hanging any consumer's teardown
for a ROM-based table, most visibly React StrictMode/unmount cleanup
calling stop() then dispose() shortly after.

Fixed by driving one more (now-instant, since the quit flag is already
set) PinmameEmscriptenStep() call directly under __EMSCRIPTEN__ instead
of busy-waiting - it runs cpu_post_run() and OnStateChange(0)
synchronously right there.

Also adds a "Stop & Dispose" button to the basic example, exercising
the same stop()-then-wait-two-frames-then-dispose() sequence consumers
use, to make this kind of regression visible without a separate app.

Confirmed fixed by hands-on testing: dispose() on a running ROM-based
table now returns immediately instead of hanging the tab.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
This commit is contained in:
valknar
2026-08-24 10:12:25 +02:00
co-authored by Claude Sonnet 5
parent 6ff116ba02
commit 43216a408e
2 changed files with 55 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
examples/basic/index.html
+30
View File
@@ -39,6 +39,13 @@
background: rgba(255,255,255,0.15); color: #eee; cursor: pointer; background: rgba(255,255,255,0.15); color: #eee; cursor: pointer;
} }
#fullscreen-button.hidden { display: none; } #fullscreen-button.hidden { display: none; }
#dispose-button {
position: absolute; top: 12px; left: 12px; z-index: 10;
padding: 8px 14px; border-radius: 6px; border: none;
background: rgba(220,38,38,0.85); color: #fff; cursor: pointer;
}
#dispose-button.hidden { display: none; }
</style> </style>
</head> </head>
<body> <body>
@@ -54,6 +61,7 @@
<button id="start-button" disabled>Loading...</button> <button id="start-button" disabled>Loading...</button>
</div> </div>
<button id="fullscreen-button" class="hidden">Fullscreen</button> <button id="fullscreen-button" class="hidden">Fullscreen</button>
<button id="dispose-button" class="hidden">Stop &amp; Dispose</button>
</div> </div>
<script type="module"> <script type="module">
@@ -66,6 +74,7 @@
const fileInput = document.getElementById('table-file'); const fileInput = document.getElementById('table-file');
const romInput = document.getElementById('rom-file'); const romInput = document.getElementById('rom-file');
const fullscreenButton = document.getElementById('fullscreen-button'); const fullscreenButton = document.getElementById('fullscreen-button');
const disposeButton = document.getElementById('dispose-button');
let uploadedTableData; let uploadedTableData;
fileInput.addEventListener('change', async () => { fileInput.addEventListener('change', async () => {
@@ -104,6 +113,7 @@
pinball.start(); pinball.start();
overlay.classList.add('hidden'); overlay.classList.add('hidden');
fullscreenButton.classList.remove('hidden'); fullscreenButton.classList.remove('hidden');
disposeButton.classList.remove('hidden');
// Touch controls are additive UI for touch-capable devices - not // Touch controls are additive UI for touch-capable devices - not
// required for desktop mouse+keyboard play. // required for desktop mouse+keyboard play.
@@ -118,6 +128,26 @@
// browser denies it) - nothing to recover from here. // browser denies it) - nothing to recover from here.
}); });
}); });
// Mirrors the stop()-then-wait-a-couple-frames-then-dispose() pattern
// consumers need: stop() only takes effect on the engine's next
// internal step, so disposing synchronously right after can race it.
disposeButton.addEventListener('click', () => {
console.log('[dispose test] calling stop()...');
pinball.stop();
requestAnimationFrame(() => {
requestAnimationFrame(() => {
console.log('[dispose test] calling dispose()...');
pinball.dispose();
console.log('[dispose test] dispose() returned - no hang');
disposeButton.classList.add('hidden');
fullscreenButton.classList.add('hidden');
overlay.classList.remove('hidden');
startButton.textContent = 'Disposed (reload page to restart)';
startButton.disabled = true;
});
});
});
</script> </script>
</body> </body>
</html> </html>
patches/vpinball/0008-emscripten-controller-stop-no-busywait.patch
+25
View File
@@ -0,0 +1,25 @@
diff --git a/plugins/pinmame/Controller.cpp b/plugins/pinmame/Controller.cpp
index 29c2405..a498fee 100644
--- a/plugins/pinmame/Controller.cpp
+++ b/plugins/pinmame/Controller.cpp
@@ -265,8 +265,20 @@ void Controller::Stop()
if (PinmameIsRunning())
{
PinmameStop();
+#ifdef __EMSCRIPTEN__
+ // PinmameStop() only sets a "please quit" flag here (see its own
+ // Emscripten branch) - there's no separate OS thread that will ever
+ // notice it and finish stopping on its own, so busy-waiting for
+ // PinmameIsRunning() to clear on this single thread would spin
+ // forever. Drive one more step directly instead: with the quit flag
+ // already set, it's a bounded, instant call that completes the
+ // pending teardown (calls cpu_post_run() and OnStateChange(0))
+ // synchronously right here.
+ PinmameEmscriptenStep();
+#else
while (PinmameIsRunning() != 0) // Wait until the machine is stopped
std::this_thread::sleep_for(std::chrono::milliseconds(75));
+#endif
if (m_onGameEndHandler)
m_onGameEndHandler(this);
}