seizeZones

Takes a set of zones together, waiting for all of them to drain, and suspends until held.

All or nothing, and that is a rule rather than a convenience: an entity that held part of a region while waiting for the rest could be waiting on a vehicle that is waiting on the part it holds. The rule prevents that outright, and it is also why ProcessModel.Entity.awaitedZone can honestly be null -- an entity is never both holding space and queuing for more. Traffic already inside the region is let out rather than trapped, which is what makes the drain terminate however busy the region is.

The extent is chosen here, at run time, and costs nothing: a link's zones by name, a junction's zone, a zone at a station, or a sample drawn from the network.

inner class Spill : Entity() {
    val cleanup = process {
        val aisle = network.link("Aisle${myAisle.value.toInt()}")!!
        seizeZones(system, aisle.zones.take(myExtent.value.toInt()), cleanupQ)
        delay(myCleanupTime)
        releaseZones(system)
    }
}

Parameters