Device for controlling the enqueuing and dequeuing operations of messages in a memory.

摘要

The subject device manages the access to message queues in a memory (6) by an enqueuer 2 and a degiieuer 7 when the enqueuer has priority over the dequeuer. It solves the contention problem raised when the dequeuer dequeues the last message from a queue while the enqueuer is enqueuing a new one. A queue control block QCB and queue status bits E, A, D are assigned to each queue and stored in memories 20 and 22. Each time dequeuer 7 performs a dequeuing operation it sets its D bit (dequeuer active) before updating the queue head field in the QCB block. When the enqueuer performs an enqueuing operation it sets an abort bit A, if it founds the D bit active and E bit active indicating that the queue contains at least one message to warn the dequeuer that it has to abort its proces if it is dequeuing the last message from the queue.