Bug 146501 – [Mac] Numerous CGColor leaks in swipe gestures

• Component: WebKit2
• Status: RESOLVED FIXED

[Joseph Pecoraro]

* SUMMARY
[Mac] Numerous CGColor leaks in swipe gestures

Unsure of the exact steps to reproduce.

* LEAK
Leak: 0x7ffee400cfb0  size=80  zone: DefaultMallocZone_0x10ab96000   CGColor  CFType  CoreGraphics
	Call stack: [thread 0x10aa86000]: 
        | 0x1 
        | start 
        | NSApplicationMain 
        | -[NSApplication run] 
        | -[BrowserApplication sendEvent:] 
        | -[NSApplication sendEvent:] 
        | -[BrowserWindow sendEvent:] 
        | -[Window sendEvent:] 
        | -[NSWindow sendEvent:] 
        | -[NSWindow _reallySendEvent:isDelayedEvent:] 
        | -[BrowserWKView scrollWheel:] 
        | -[WKView scrollWheel:] 
        | WebKit::ViewGestureController::handleScrollWheelEvent(NSEvent*) 
        | WebKit::ViewGestureController::trackSwipeGesture(NSEvent*, WebKit::ViewGestureController::SwipeDirection) 
        | -[NSEvent trackSwipeEventWithOptions:dampenAmountThresholdMin:max:usingHandler:] 
        | -[NSEvent _trackSwipeEventWithOptions:dampenAmountThresholdMin:max:trackingDistance:axis:velocityFilterClass:usingHandler:] 
        | ___trackSwipeWithScrollEvent_block_invoke 
        | ___ZN6WebKit21ViewGestureController17trackSwipeGestureEP7NSEventNS0_14SwipeDirectionE_block_invoke 
        | WebKit::ViewGestureController::beginSwipeGesture(WebKit::WebBackForwardListItem*, WebKit::ViewGestureController::SwipeDirection) 
        | CGColorCreateGenericGray 
        | create_color 
        | CGTypeCreateInstance 
        | _CFRuntimeCreateInstance 
        | malloc_zone_malloc 

* NOTES
- ViewGestureController::beginSwipeGesture certainly looks like it leaks:

        [m_swipeShadowLayer setColors:@[
            (id)CGColorCreateGenericGray(0, 1.),
            (id)CGColorCreateGenericGray(0, 0.99),
            (id)CGColorCreateGenericGray(0, 0.98),
            (id)CGColorCreateGenericGray(0, 0.95),
            ...
        ]];

[Joseph Pecoraro]

What is the elegant way to do this without leaking? Is it this?

  (id)adoptCF(CGColorCreateGenericGray(...)).get()

[Joseph Pecoraro]

Created attachment 255908 [details]
[PATCH] Proposed Fix

Seems to work!

[Tim Horton]

Comment on attachment 255908 [details]
[PATCH] Proposed Fix

Woah, good catch. Thankfully never shipped.

[WebKit Commit Bot]

Comment on attachment 255908 [details]
[PATCH] Proposed Fix

Clearing flags on attachment: 255908

Committed r186174: <http://trac.webkit.org/changeset/186174>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

Comment on attachment 255908 [details]
[PATCH] Proposed Fix

View in context: https://bugs.webkit.org/attachment.cgi?id=255908&action=review

> Source/WebKit2/UIProcess/mac/ViewGestureControllerMac.mm:640
> +            (id)adoptCF(CGColorCreateGenericGray(0, 1.)).get(),

Cries out for a helper function.