Module holochain::core::queue_consumer

Manages the spawning of tasks which process the various work queues in the system, as well as notifying subsequent queue processors to pick up the work that was left off.

The following table lays out the queues and the workflows that consume them, as well as the follow-up workflows. A “source” queue is a database which feeds data to the workflow, and a “destination” queue is a database which said workflow writes to as part of its processing of its source queue.

workflow	source queue	dest. queue	notifies
gossip path
HandleGossip	n/a	ValidationQueue	SysValidation
SysValidation	ValidationQueue	ValidationQueue	AppValidation
AppValidation	ValidationQueue	ValidationQueue	DhtOpIntegr.
authoring path
CallZome	n/a	ChainSequence	ProduceDhtOps
ProduceDhtOps	ChainSequence	Auth’d + IntQ †	DhtOpIntegr.
integration, common to both paths
DhtOpIntegr.	IntegrationLimbo	IntegratedDhtOps	SysVal + VR
ValReceipt.	IntegratedDhtOps	IntegratedDhtOps	*n/a
Publish	AuthoredDhtOps	n/a	n/a

(† Auth’d + IntQ is short for: AuthoredDhtOps + IntegrationLimbo)

Implicitly, every workflow also writes to its own source queue, i.e. to remove the item it has just processed.

Structs

• InitialQueueTriggers
  The triggers to run once at the start of a cell
• QueueConsumerMap
  Map of running queue consumers workflows per dna space.
• QueueTriggerClosedError
  The only error possible when attempting to trigger: the channel is closed
• QueueTriggers
  The entry points for kicking off a chain reaction of queue activity
• TriggerReceiver
  The receiving end of a queue trigger channel
• TriggerSender
  The means of nudging a queue consumer to tell it to look for more work

Enums

• WorkComplete
  Declares whether a workflow has exhausted the queue or not

Functions

• spawn_queue_consumer_tasks
  Spawns several long-running tasks which are responsible for processing work which shows up on various databases.