author Kartikaya Gupta <>
Wed, 30 May 2018 15:54:50 -0400
changeset 420571 8a1bdb8d8bf5a1c8869bf3f82fd86c56f9f4b72c
parent 413094 787dce710dce6dff0d9f9e7621c9dac676843678
child 459343 847aa80e92e872bbbfb986c0fd0645efff5b3ae4
permissions -rw-r--r--
Bug 1457590 - Strengthen the contract around recycling HitTestingTreeNodes. r=botond This patch makes three related changes: - A non-functional change that factors a IsRecyclable function on HitTestingTreeNode. - A non-functional change that sprinkles proof-of-tree-lock arguments to a few HitTestingTreeNode functions, to ensure at compile-time that they can only be called while holding the tree lock. - A functional change that stops clearing mLayersId in HitTestingTreeNode::Destroy, so that if a node is non-recyclable, and it gets Destroy()'d while other code still has a RefPtr to it, that other code can still read the layers id off in a safe manner. These changes provide a stronger set of checks around node recycling, and allows for a safe mechanism to use a HitTestingTreeNode on the controller thread without having to lock the entire APZ tree. The mechanism is effectively a per-node lock, which will be added in the next patch. MozReview-Commit-ID: DBIjFDZJwhE