@startuml
skinparam classFontSize 8
skinparam classFontName Helvetica
autonumber

participant "Application" as app
participant "User Callback" as callback
participant "Job" as job

participant "Task Pool public API" as TP
participant "Dispatch queue" as queue
participant "Worker Threads" as workers

box "Task Pool" #LightBlue
    participant TP
    participant queue
    participant workers
end box

== Create Task Pool ==

activate app

app -[#blue]> TP: IotTaskPool_Create: create a Task 
TP -> queue: Initialize dispatch queue
activate queue
TP -> workers: Create minimum number of worker threads
activate workers
TP --[#blue]> app
activate TP
workers -> workers: Wait on incoming jobs

== Use Task Pool ==

loop Application loop: Create and schedule jobs
	app -[#blue]> TP: IotTaskPool_CreateRecyclableJob: create a job
	TP --[#blue]> app
	activate job
	note left: job status: //ready//
	
	app -[#blue]> TP: IotTaskPool_Schedule: schedule a job
	TP -> queue: Queue job
	TP -> TP: Grow pool up to maximum threads, if all threads are busy
	TP -> workers: Signal incoming job
	TP --[#blue]> app
	note left: job status: //scheduled//
	
	loop Outer dispatch loop: Wait on incoming jobs
		workers -> queue: Dequeue next job
		loop Inner dispatch loop: Execute any queue jobs in order
			workers -[#green]> job: Invoke user callback
			note left: job status: //executing//
			job -[#green]> callback: Invoke
			activate callback
			callback -[#blue]> TP: IotTaskPool_RecycleJob: recycles job
			TP --[#blue]> callback
			note left: job status: //completed//
			deactivate job
			deactivate callback
			workers -> workers: Move to next job
		end
		workers -> workers: Wait on incoming jobs
	end
	
end
	
== Destroy Task Pool ==

    app -[#blue]> TP: IotTaskPool_Destroy: destroy the task pool
	TP -> workers: Shutdown worker threads
	deactivate workers
	TP -> queue: Destroy all jobs in the dispatch queue
	deactivate queue
    TP --[#blue]> app
	deactivate TP

@enduml