HIDManager Wierd CFRunLoop终止 [英] HIDManager Wierd CFRunLoop Termination

问题描述

我已经创建了设备匹配和设备删除回调，并且需要运行CFRunLoop以便在插入和删除设备时调用这些回调.

I've created device matching and device removal callbacks, And need to run CFRunLoop to get those callbacks invoked whenever device plugged in and removed.

但是问题是，DeviceMatching回调需要大量的处理时间，并且取决于要连接的设备，因此我想通过在有限的时间内运行CFRunLoop来检测是否删除了设备，并且发生了设备删除回调

But the problem is, DeviceMatching callback takes a lot of processing time and depends on device to be attached, So I want to detect if device is removed by running the CFRunLoop for a limited time, and With that the device removal callback happens.

但是，它可以工作2次，然后抛出exe_bad_access.

But, It works for 2 times and then it throws exe_bad_access.

  IOHIDManagerSetDeviceMatching( tIOHIDManagerRef, matchingCFDictRef );
  if( matchingCFDictRef ) {
        CFRelease( matchingCFDictRef );
  }
  IOHIDManagerRegisterDeviceMatchingCallback(tIOHIDManagerRef,
                                                 Handle_DeviceMatchingCallback,NULL);
  IOHIDManagerRegisterDeviceRemovalCallback(tIOHIDManagerRef, Handle_RemovalCallback, NULL);

  IOHIDManagerScheduleWithRunLoop(tIOHIDManagerRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
      CFRunLoopRun();

设备添加回调

static void Handle_DeviceMatchingCallback(void* inContext, IOReturn inResult, 
                             void* inSender, IOHIDDeviceRef  inIOHIDDeviceRef) {
      //DO SOME HEAVY PROCESSING

      //NOW WE NEED TO CHECK IF DEVICE IS STILL CONNECTED
     [[NSRunLoop currentRunLoop]  runUntilDate:[NSDate dateWithTimeIntervalSinceNow:1]];

      //DO POST PROCESSING

}

设备移除回调:

static void Handle_RemovalCallback( void* inContext,IOReturn  inResult,
                        void*  inSender, IOHIDDeviceRef inIOHIDDeviceRef) {
     //NOW THIS GET's INVOKED, after keeping in run loop

}

以下是用于生成匹配CFDictRef

Following is the code for generating matchingCFDictRef

CFMutableDictionaryRef matchDict = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);

    CFNumberRef vendorIDCFNumRef  = CFNumberCreate( kCFAllocatorDefault, kCFNumberIntType, &vendorId );
    CFNumberRef productIDCFNumRef = CFNumberCreate( kCFAllocatorDefault, kCFNumberIntType, &productId );

    CFDictionarySetValue( matchDict, CFSTR( kIOHIDVendorIDKey  ), vendorIDCFNumRef );
    CFDictionarySetValue( matchDict, CFSTR( kIOHIDProductIDKey ), productIDCFNumRef );

    CFRelease( vendorIDCFNumRef );
    CFRelease( productIDCFNumRef );

推荐答案

如何生成matchingCFDictRef?尽管通常的约定会建议IOHIDManager保留或复制它，但有可能不是.我现在尝试将CFRelease取出，看看是否有改善.

How do you generate matchingCFDictRef? Though normal conventions would suggest that IOHIDManager should retain or copy it, it's possible that it isn't. I would try taking out the CFRelease for now and see if that improves things.

CFGetTypeID中的崩溃表明它正在尝试使用已释放的CF对象.您可以尝试调试以下几项:

The crash in CFGetTypeID indicates that it is trying to work with a CF object that has been freed. A few things you can do to try to debug which one it is:

• 打开 NSZombie .即使这是一个CF对象，它也可能会起作用(许多CF对象都是免费桥接的，并且仍然可以使用).
• 在调试器中，检查CFGetType的参数.请参阅在gdb 获取正确的寄存器，具体取决于您的处理器. (此页面用于ObjC并不重要；您只需要与arg0有关的全部内容即可.)

• Turn on NSZombie. It might work, even though this is a CF object (many CF objects are toll free bridged and will still work).
• In the debugger, check the parameter to CFGetType. See Inspecting Obj-C parameters in gdb for the correct register depending on your processor. (It doesn't matter that this page is for ObjC; you just want the entires related to arg0.)

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