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fix: remove deadlock in pt_usleep sleep-spam blocker (can hang render thread → os_unfair_lock crash) #234

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fix: remove deadlock in pt_usleep sleep-spam blocker (can hang render thread → os_unfair_lock crash) #234

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25 changes: 4 additions & 21 deletions PlayTools/PlayLoader.m
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Original file line number Diff line number Diff line change
Expand Up @@ -331,14 +331,11 @@ static int pt_unlink(char const* path) {
static NSMutableDictionary *thread_sleep_counters = nil;
static NSMutableDictionary *last_sleep_attempts = nil;
static dispatch_once_t thread_sleep_once;
static NSLock *thread_sleep_lock = nil;

static int pt_usleep(useconds_t time) {
dispatch_once(&thread_sleep_once, ^{
thread_sleep_counters = [NSMutableDictionary dictionary];
last_sleep_attempts = [NSMutableDictionary dictionary];
thread_sleep_lock = [[NSLock alloc] init];
[thread_sleep_lock lock];
});

if ([[PlaySettings shared] blockSleepSpamming]) {
Expand Down Expand Up @@ -367,14 +364,10 @@ static int pt_usleep(useconds_t time) {
}

if (exceeded_sleep_limit) {
// Stop this thread from spamming usleep calls
NSLog(@"[PC] Thread %i exceeded usleep limit. Seem sus, stopping this "
@"thread FOREVER",
thread_id);

[thread_sleep_lock lock];
[thread_sleep_lock unlock];

// Stop this thread from spamming usleep calls by skipping the sleep.
// Do NOT block/hang the thread: hanging a render/GPU thread here is what
// caused os_unfair_lock corruption and crashes in Unity games (e.g. Endfield).
NSLog(@"[PC] Thread %i exceeded usleep limit. Skipping its sleeps.", thread_id);
return 0;
}
}
Expand Down Expand Up @@ -404,16 +397,6 @@ static void __attribute__((constructor)) initialize(void) {
if (ue_status == 2) {
[PlayKeychain debugLogger: [NSString stringWithFormat:@"UnrealEngine Hooked"]];
}

if ([[PlaySettings shared] blockSleepSpamming]) {
// Add an observer so we can unlock threads on app termination
[[NSNotificationCenter defaultCenter] addObserverForName:UIApplicationWillTerminateNotification
object:nil
queue:[NSOperationQueue mainQueue]
usingBlock:^(NSNotification * _Nonnull note) {
[thread_sleep_lock unlock];
}];
}
}

@end
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