Backpressure path — send to receive, replies dashed

Serial flow from sending handler to receiving handler · the Completion connection returns terminal reply·error

Backpressure path — send to receive, replies dashed Serial flow from sending handler to receiving handler · the Completion connection returns terminal reply·error sending handler · SendToChannel(...) · Architecture component sending handler SendToChannel(...) Core send queue · accounted-byte HWM · Architecture component Core send queue accounted-byte HWM Application · connection · Architecture component Application connection Core receive queue · accounted-byte HWM · Architecture component Core receive queue accounted-byte HWM App job queue · reserved + queued permits · Architecture component App job queue reserved + queued permits receiving handler · Architecture component receiving handler Completion · connection · Architecture component Completion connection terminal reply·error

Serial flow (solid)

  • • Runs in order: sending handler → Core ordinary send queue → Application connection → Core ordinary receive queue → application job queue → receiving handler.
  • • The Core send/receive queues cap bytes with the accounted-byte HWM, and the application job queue caps the number of jobs waiting for a handler with reserved + queued permits.

Return path (dashed)

  • • The receiving handler returns terminal reply·error over the Completion connection (dashed), and the Completion connection leads back to the sending handler.
  • • The Completion connection keeps reading even while application receiving is stopped, so an in-flight request finishes. The Application connection carries ordinary messages·requests plus Framework control (heartbeat·topology·relocation·SendReady kind 12).