PresentSync

For symmetry, a PresentSync block is added, which does the waiting for fences for each received packet from upstream before sending it downstream. The block spawns a thread that waits for fences in the order of the packets received and send them downstream once fences are reached. This block is useful if blocks downstream require synchronous access of packet data.

For example, a PresentSync block can be inserted between the Producer and the memory boundary IPC block to keep packets from queuing for sending until their contents are ready; primarily when the memory boundary IPC block uses a mailbox queue.