Potential issue with standard main loop in NDK samples #1094
Description
The main loop used in many Android NDK samples follows this standard structure:
void android_main(android_app* state)
{
...
while (!state->destroyRequested) {
android_poll_source* source = nullptr;
int result = ALooper_pollOnce(g_engine.IsReady() ? 0 : -1, nullptr, nullptr, (void**)&source);
if (result == ALOOPER_POLL_ERROR)
break;
if (source != nullptr)
source->process(state, source);
// Issue: This code is executed even after state->destroyRequested is set to true
if (g_engine.IsReady())
g_engine.DrawFrame();
}
...
}Issue:
state->destroyRequested is set to true in source->process(state, source) when a "destroy" event occurs. However, the code continues executing after state->destroyRequested is set which can lead to undefined behavior, e.g. accessing released resources.
Potential Fix:
android_poll_source* source;
while (ALooper_pollOnce(g_engine.IsReady() ? 0 : -1, nullptr, nullptr, reinterpret_cast<void**>(&source)) != ALOOPER_POLL_ERROR) {
if (source != nullptr) {
source->process(state, source);
// Exit loop immediately after destroy is requested
if (state->destroyRequested != 0)
break;
}
if (g_engine.IsReady())
g_engine.DrawFrame();
}