Element ordering handling in a ring buffer

Abstract

Data processing apparatuses, methods of data processing, complementary instructions and programs related to ring buffer administration are disclosed. An enqueuing operation performs an atomic compare-and-swap oper-ation to store a first processed data item indication to an enqueuing-target slot in the ring buffer contingent on an in-order marker not being present there and, when successful, determines that a ready-to-dequeue condition is true for the first processed data item indication. A dequeuing operation, when the ready-to-de-queue condition for a dequeuing-target slot is true, comprises writing a null data item to the dequeuing-target slot and, when dequeuing in-order, further comprises, dependent on whether a next contiguous slot has null content, determining a retirement condition and, when the retirement condition is true, performing a retirement process on the next contiguous slot comprising making the next con-tiguous slot available to a subsequent enqueuing operation. Further subsequent slots may also be retired.