Fix deadlock by removing lock in frameNavigated #942
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ankur22
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Jun 19, 2023
In certain navigations, the current frame may have child frames. In these cases, the child frames need to be removed. frameNavigated holds on to a framesMu lock for the whole duration of the frameNavigated. removeFramesRecursively, which is what removes the child frames, needs the same lock so that it can amend the synchronised variable. It's also worth noting that this also prevent frameNavigated holding on to a lock when it calls ChildFrames, which requires another lock. It's generally unsafe to hold onto more than one lock at a time.
This test actually tests that we can navigate to a page with iframes, click on a link, which navigates to another page with iframes. Once at the second page it will end the test and we can assert. Without the fix in the prior commit, this would panic on a deadlock. NOTE: This only works when we have headless mode on.
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Description of changes
In certain navigations, the current frame may have child frames (e.g.
iframes within a root frame). In these cases, the child frames need to be removed during a navigation. Before this changeframeNavigatedheld ontoframesMulock for the whole duration offrameNavigated, but when it determined that the current root frame held child frames, it would callremoveFramesRecursively.removeFramesRecursively, which is what removes the child frames, needs the same lock (framesMu) so it can amend the synchronised variable which holds all references to the frames on the current page.It's also worth noting that this also prevents
frameNavigatedholding on to a lock when it callsChildFrames, which requires another lock. It's generally unsafe to hold onto more than one lock at a time.Closes: #941
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