On Mon, May 15, 2017 at 02:07:21AM -0700, Davidlohr Bueso wrote: > + * Fairness and freedom of starvation are guaranteed by the lack of lock > + * stealing, thus range locks depend directly on interval tree semantics. > + * This is particularly for iterations, where the key for the rbtree is > + * given by the interval's low endpoint,
So suppose the lock is held at [a,n], and I want to acquire [g,z], this conflicts, therefore I wait. While I wait, someone else comes in at [b,m], they too wait. [a,n] is released, per ordering [b,m] acquires, I still wait. [a,n] returns to wait. [b,m] releases, does the iteration then restart and grant it to [a,n] or will I (at [g,z]) finally acquire? Since the code always does range_interval_tree_foreach() it would appear to me [b,m] will always win and [g,z] could be made to wait indefinitely (by always contending with another range that has a lower starting point). > and duplicates are walked as it > + * would an inorder traversal of the tree. Are duplicates ordered in FIFO ? Afaict the above is free of actual semantics.
