nupp.host.pump

nupp.host.pump runs one operation at a time for an application that embeds the runtime and owns its own loop. Reach for it from the exports such an application calls, so that an operation which waits -- on a nupp.host request, a timer, the network -- parks instead of blocking the call that started it.

start runs an operation until it finishes or parks, and says which; the application keeps calling poll from its loop, after answering whatever it was asked, until the operation finishes. Each poll is one non-blocking pass over the runtime's readiness sources, and an operation they make ready resumes inside that pass.

local pump = nupp.host.pump

local session = pump.newPump()

export function frame(dt: number): pump.State
    if session:parked() then
        return session:poll()
    end
    return session:start(function(): boolean
        return update(dt)
    end)
end

An operation returns whether the application should keep running: false reports "stopped", anything else "continue". A failure is raised from the start or poll that observes it. cancel unwinds a parked operation, raising a cancellation inside it, so its cleanup runs before the application shuts down.

record Pump ...

handler: suspensionContract.Handler

active: thread?

result: boolean?

failure: any?

start: function start(self: Pump, body: function(): boolean?): State

poll: function poll(self: Pump): State

parked: function parked(self: Pump): boolean

cancel: function cancel(self: Pump): nil

type State = "parked" | "continue" | "stopped"

function newPump(): Pump