Optimize _glfwInitJoysticks on OS X.

This function used to enumerate all devices and capture all properties
of every device into a dictionary. This takes 180 ms on a MacBook Pro
without external devices and 280 ms with an external keyboard/mouse
attached.

Since we're only interested in a few properties, we can just get them
one by one - this reduces the time to <1 ms.

Note that we still use the dictionary to get the joystick elements.
For unknown reason this is required to get all axes/buttons - without
doing this we don't get any joystick elements in addJoystickElement.

Closes #332.

README.md

@@ -81,6 +81,7 @@ GLFW bundles a number of dependencies in the `deps/` directory.
                    found for a given `CGDisplay`
  - [Cocoa] Bugfix: Modifier key events were lost if the corresponding modifier
                    bit field was unchanged
+ - [Cocoa] Bugfix: Joystick enumeration took hundreds of ms on some systems
  - [Win32] Enabled generation of pkg-config file for MinGW
  - [Win32] Bugfix: Failure to load winmm or its functions was not reported to
                    the error callback
@@ -160,6 +161,7 @@ skills.
  - heromyth
  - Paul Holden
  - Toni Jovanoski
+ - Arseny Kapoulkine
  - Osman Keskin
  - Cameron King
  - Peter Knut

src/iokit_joystick.m

@@ -324,9 +324,41 @@ void _glfwInitJoysticks(void)
         HRESULT plugInResult = S_OK;
         SInt32 score = 0;
 
-        long usagePage, usage;
+        long usagePage = 0;
+        long usage = 0;
+
+        valueRef = IORegistryEntryCreateCFProperty(ioHIDDeviceObject,
+                                                   CFSTR(kIOHIDPrimaryUsagePageKey),
+                                                   kCFAllocatorDefault, kNilOptions);
+        if (valueRef)
+        {
+            CFNumberGetValue(valueRef, kCFNumberLongType, &usagePage);
+            CFRelease(valueRef);
+        }
+
+        valueRef = IORegistryEntryCreateCFProperty(ioHIDDeviceObject,
+                                                   CFSTR(kIOHIDPrimaryUsageKey),
+                                                   kCFAllocatorDefault, kNilOptions);
+        if (valueRef)
+        {
+            CFNumberGetValue(valueRef, kCFNumberLongType, &usage);
+            CFRelease(valueRef);
+        }
+
+        if (usagePage != kHIDPage_GenericDesktop)
+        {
+            // This device is not relevant to GLFW
+            continue;
+        }
+
+        if ((usage != kHIDUsage_GD_Joystick &&
+             usage != kHIDUsage_GD_GamePad &&
+             usage != kHIDUsage_GD_MultiAxisController))
+        {
+            // This device is not relevant to GLFW
+            continue;
+        }
         
-        // Check device type
         result = IORegistryEntryCreateCFProperties(ioHIDDeviceObject,
                                                    &propsRef,
                                                    kCFAllocatorDefault,
@@ -335,33 +367,6 @@ void _glfwInitJoysticks(void)
         if (result != kIOReturnSuccess)
             continue;
 
-        valueRef = CFDictionaryGetValue(propsRef, CFSTR(kIOHIDPrimaryUsagePageKey));
-        if (valueRef)
-        {
-            CFNumberGetValue(valueRef, kCFNumberLongType, &usagePage);
-            if (usagePage != kHIDPage_GenericDesktop)
-            {
-                // This device is not relevant to GLFW
-                CFRelease(propsRef);
-                continue;
-            }
-        }
-
-        valueRef = CFDictionaryGetValue(propsRef, CFSTR(kIOHIDPrimaryUsageKey));
-        if (valueRef)
-        {
-            CFNumberGetValue(valueRef, kCFNumberLongType, &usage);
-
-            if ((usage != kHIDUsage_GD_Joystick &&
-                 usage != kHIDUsage_GD_GamePad &&
-                 usage != kHIDUsage_GD_MultiAxisController))
-            {
-                // This device is not relevant to GLFW
-                CFRelease(propsRef);
-                continue;
-            }
-        }
-
         _GLFWjoystickIOKit* joystick = _glfw.iokit_js + joy;
         joystick->present = GL_TRUE;