Actually, don’t use rumble threads at all, because IOHIDDeviceSetReport seems to queue stuff despite being blocking

Cocoa/GBView.m

@@ -272,9 +272,7 @@
 
 - (void)setRumble:(double)amp
 {
-    dispatch_async(dispatch_get_main_queue(), ^{
     [lastController setRumbleAmplitude:amp];
-    });
 }
 
 - (void)controller:(JOYController *)controller movedAxis:(JOYAxis *)axis

JoyKit/JOYController.m

@@ -39,8 +39,6 @@ static bool axesEmulateButtons = false;
 static bool axes2DEmulateButtons = false;
 static bool hatsEmulateButtons = false;
 
-static NSLock *globalRumbleThreadLock;
-
 @interface JOYController ()
 + (void)controllerAdded:(IOHIDDeviceRef) device;
 + (void)controllerRemoved:(IOHIDDeviceRef) device;
@@ -95,8 +93,10 @@ static void HIDInput(void *context, IOReturn result, void *sender, IOHIDValueRef
 static void HIDReport(void *context, IOReturn result, void *sender, IOHIDReportType type,
                       uint32_t reportID, uint8_t *report, CFIndex reportLength)
 {
+    if (reportLength) {
         [(__bridge JOYController *)context gotReport:[[NSData alloc] initWithBytesNoCopy:report length:reportLength freeWhenDone:NO]];
     }
+}
 
 typedef struct __attribute__((packed)) {
     uint8_t reportID;
@@ -152,12 +152,9 @@ typedef union {
     bool _isSwitch; // Does this controller use the Switch protocol?
     bool _isDualShock3; // Does this controller use DS3 outputs?
     JOYVendorSpecificOutput _lastVendorSpecificOutput;
-    NSLock *_rumbleThreadLock;
+    volatile double _rumbleAmplitude;
-    volatile double _rumblePWMRatio;
     bool _physicallyConnected;
     bool _logicallyConnected;
-    bool _rumbleThreadRunning;
-    volatile bool _forceStopRumbleThread;
     
     NSDictionary *_hacks;
     NSMutableData *_lastReport;
@@ -166,7 +163,8 @@ typedef union {
     JOYElement *_previousAxisElement;
     
     uint8_t _playerLEDs;
-
+    double _sentRumbleAmp;
+    unsigned _rumbleCounter;
 }
 
 - (instancetype)initWithDevice:(IOHIDDeviceRef) device hacks:(NSDictionary *)hacks
@@ -358,7 +356,6 @@ typedef union {
     _axes2DEmulatedButtons = [NSMutableDictionary dictionary];
     _hatEmulatedButtons = [NSMutableDictionary dictionary];
     _iokitToJOY = [NSMutableDictionary dictionary];
-    _rumbleThreadLock = [[NSLock alloc] init];
     
     
     //NSMutableArray *axes3d = [NSMutableArray array];
@@ -368,10 +365,6 @@ typedef union {
     _isDualShock3 = [_hacks[JOYIsDualShock3] boolValue];
 
     NSDictionary *customReports = hacks[JOYCustomReports];
-    
-    if (hacks[JOYCustomReports]) {
-        _multiElements = [NSMutableDictionary dictionary];
-        _fullReportElements = [NSMutableDictionary dictionary];
     _lastReport = [NSMutableData dataWithLength:MAX(
                                                     MAX(
                                                         [(__bridge NSNumber *)IOHIDDeviceGetProperty(device, CFSTR(kIOHIDMaxInputReportSizeKey)) unsignedIntValue],
@@ -381,6 +374,11 @@ typedef union {
                                                     )];
     IOHIDDeviceRegisterInputReportCallback(device, _lastReport.mutableBytes, _lastReport.length, HIDReport, (void *)self);
 
+    if (hacks[JOYCustomReports]) {
+        _multiElements = [NSMutableDictionary dictionary];
+        _fullReportElements = [NSMutableDictionary dictionary];
+
+        
         for (NSNumber *_reportID in customReports) {
             signed reportID = [_reportID intValue];
             bool isOutput = false;
@@ -555,7 +553,7 @@ typedef union {
 - (void)gotReport:(NSData *)report
 {
     JOYFullReportElement *element = _fullReportElements[@(*(uint8_t *)report.bytes)];
-    if (!element) return;
+    if (element) {
         [element updateValue:report];
         
         NSArray<JOYElement *> *subElements = _multiElements[element];
@@ -563,9 +561,10 @@ typedef union {
             for (JOYElement *subElement in subElements) {
                 [self _elementChanged:subElement];
             }
-        return;
         }
     }
+    [self updateRumble];
+}
 
 - (void)elementChanged:(IOHIDElementRef)element
 {
@@ -697,7 +696,6 @@ typedef union {
         }
     }
     _physicallyConnected = false;
-    [self _forceStopRumbleThread]; // Stop the rumble thread.
     [exposedControllers removeObject:self];
     _device = nil;
 }
@@ -731,43 +729,30 @@ typedef union {
     }
 }
 
-- (void)rumbleThread
+- (void)updateRumble
 {
-    unsigned rumbleCounter = 0;
+    if (!self.connected) {
+        return;
+    }
     if (_rumbleElement.max == 1 && _rumbleElement.min == 0) {
-        while (self.connected && !_forceStopRumbleThread) {
+        double ampToSend = _rumbleCounter < round(_rumbleAmplitude * PWM_RESOLUTION);
-            if ([_rumbleElement setValue:rumbleCounter < round(_rumblePWMRatio * PWM_RESOLUTION)]) {
+        if (ampToSend != _sentRumbleAmp) {
-                break;
+            [_rumbleElement setValue:ampToSend];
-            }
+            _sentRumbleAmp = ampToSend;
-            rumbleCounter += round(_rumblePWMRatio * PWM_RESOLUTION);
-            if (rumbleCounter >= PWM_RESOLUTION) {
-                rumbleCounter -= PWM_RESOLUTION;
         }
+        _rumbleCounter += round(_rumbleAmplitude * PWM_RESOLUTION);
+        if (_rumbleCounter >= PWM_RESOLUTION) {
+            _rumbleCounter -= PWM_RESOLUTION;
         }
     }
     else {
-        while (self.connected && !_forceStopRumbleThread) {
+        if (_rumbleAmplitude == _sentRumbleAmp) {
-            [_rumbleElement setValue:_rumblePWMRatio * (_rumbleElement.max - _rumbleElement.min) + _rumbleElement.min];
+            return;
         }
-    }
+        _sentRumbleAmp = _rumbleAmplitude;
-    [_rumbleThreadLock lock];
-    [_rumbleElement setValue:0];
-    _rumbleThreadRunning = false;
-    _forceStopRumbleThread = false;
-    [_rumbleThreadLock unlock];
-}
-
-- (void)setRumbleAmplitude:(double)amp /* andFrequency: (double)frequency */
-{
-    double frequency = 144; // I have no idea what I'm doing.
-    
-    if (amp < 0) amp = 0;
-    if (amp > 1) amp = 1;
         if (_isSwitch) {
-        if (amp == 0) {
+            double frequency = 144;
-            amp = 1;
+            double amp = _rumbleAmplitude;
-            frequency = 0;
-        }
             
             uint8_t highAmp = amp * 0x64;
             uint8_t lowAmp = amp * 0x32 + 0x40;
@@ -801,33 +786,21 @@ typedef union {
         }
         else if (_isDualShock3) {
             _lastVendorSpecificOutput.ds3Output.reportID = 1;
-        _lastVendorSpecificOutput.ds3Output.rumbleLeftDuration = _lastVendorSpecificOutput.ds3Output.rumbleRightDuration = amp? 0xff : 0;
+            _lastVendorSpecificOutput.ds3Output.rumbleLeftDuration = _lastVendorSpecificOutput.ds3Output.rumbleRightDuration = _rumbleAmplitude? 0xff : 0;
-        _lastVendorSpecificOutput.ds3Output.rumbleLeftStrength = _lastVendorSpecificOutput.ds3Output.rumbleRightStrength = amp * 0xff;
+            _lastVendorSpecificOutput.ds3Output.rumbleLeftStrength = _lastVendorSpecificOutput.ds3Output.rumbleRightStrength = round(_rumbleAmplitude * 0xff);
             [self sendReport:[NSData dataWithBytes:&_lastVendorSpecificOutput.ds3Output length:sizeof(_lastVendorSpecificOutput.ds3Output)]];
         }
         else {
-        [_rumbleThreadLock lock];
+            [_rumbleElement setValue:_rumbleAmplitude * (_rumbleElement.max - _rumbleElement.min) + _rumbleElement.min];
-        _rumblePWMRatio = amp;
+        }
-        if (!_rumbleThreadRunning) { // PWM thread not running, start it.
+    }
-            if (amp != 0) {
+}
-                /* TODO: The PWM thread does not handle correctly the case of having a multi-port controller where more
-                 than one controller uses rumble. At least make sure any sibling controllers don't have their
-                 PWM thread running. */
 
-                [globalRumbleThreadLock lock];
+- (void)setRumbleAmplitude:(double)amp /* andFrequency: (double)frequency */
-                for (JOYController *controller in [JOYController allControllers]) {
+{
-                    if (controller != self && controller->_device == _device) {
+    if (amp < 0) amp = 0;
-                        [controller _forceStopRumbleThread];
+    if (amp > 1) amp = 1;
-                    }
+    _rumbleAmplitude = amp;
-                }
-                _rumblePWMRatio = amp;
-                _rumbleThreadRunning = true;
-                [self performSelectorInBackground:@selector(rumbleThread) withObject:nil];
-                [globalRumbleThreadLock unlock];
-            }
-        }
-        [_rumbleThreadLock unlock];
-    }
 }
 
 - (bool)isConnected
@@ -835,16 +808,6 @@ typedef union {
     return _logicallyConnected && _physicallyConnected;
 }
 
-- (void)_forceStopRumbleThread
-{
-    [_rumbleThreadLock lock];
-    if (_rumbleThreadRunning) {
-        _forceStopRumbleThread = true;
-    }
-    [_rumbleThreadLock unlock];
-    while (_rumbleThreadRunning);
-}
-
 + (void)controllerAdded:(IOHIDDeviceRef) device
 {
     NSString *name = (__bridge NSString *)IOHIDDeviceGetProperty(device, CFSTR(kIOHIDProductKey));
@@ -902,7 +865,6 @@ typedef union {
     
     controllers = [NSMutableDictionary dictionary];
     exposedControllers = [NSMutableArray array];
-    globalRumbleThreadLock = [[NSLock alloc] init];
     NSArray *array = @[
         CreateHIDDeviceMatchDictionary(kHIDPage_GenericDesktop, kHIDUsage_GD_Joystick),
         CreateHIDDeviceMatchDictionary(kHIDPage_GenericDesktop, kHIDUsage_GD_GamePad),