Simulation.Aivika.Trans.Resource.Preemption.Base

Tested with: GHC 8.0.1

This module defines the preemptible resource.

The module is optimised in the sense that this kind of the resource has neither additional signals, nor counters that would may slow down the simulation.

Documentation

class MonadDES m => MonadResource m where

A type class of monads whithin which we can create preemptible resources.

Minimal complete definition

newResource, newResourceWithMaxCount, resourceCount, resourceMaxCount, requestResourceWithPriority, releaseResource, usingResourceWithPriority, incResourceCount, decResourceCount, alterResourceCount

Associated Types

data Resource m

Represents a preemptible resource.

Methods

newResource :: Int -> Simulation m (Resource m)

Create a new resource with the specified initial count that becomes the upper bound as well.

newResourceWithMaxCount :: Int -> Maybe Int -> Simulation m (Resource m)

Create a new resource with the specified initial and maximum counts, where Nothing means that the resource has no upper bound.

resourceCount :: Resource m -> Event m Int

Return the current count of the resource.

resourceMaxCount :: Resource m -> Maybe Int

Return the maximum count of the resource, where Nothing means that the resource has no upper bound.

requestResourceWithPriority :: Resource m -> Double -> Process m ()

Request with the priority for the resource decreasing its count in case of success, otherwise suspending the discontinuous process until some other process releases the resource.

It may preempt another process if the latter aquired the resource before but had a lower priority. Then the current process takes an ownership of the resource.

releaseResource :: Resource m -> Process m ()

Release the resource increasing its count and resuming one of the previously suspended or preempted processes as possible.

usingResourceWithPriority :: Resource m -> Double -> Process m a -> Process m a

Acquire the resource with the specified priority, perform some action and safely release the resource in the end, even if the IOException was raised within the action.

incResourceCount :: Resource m -> Int -> Event m ()

Increase the count of available resource by the specified number, invoking the awaiting and preempted processes according to their priorities as needed.

decResourceCount :: Resource m -> Int -> Event m ()

Decrease the count of available resource by the specified number, preempting the processes according to their priorities as needed.

alterResourceCount :: Resource m -> Int -> Event m ()

Alter the resource count either increasing or decreasing it by calling incResourceCount or decResourceCount respectively.