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

Arguments

:: Int

the initial count (and maximal count too) of the resource

-> Simulation m (Resource m)

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

newResourceWithMaxCount

Arguments

:: Int

the initial count of the resource

-> Maybe Int

the maximum count of the resource, which can be indefinite

-> 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

Arguments

:: Resource m

the requested resource

-> Double

the priority (the less value has a higher priority)

-> 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

Arguments

:: Resource m

the resource to release

-> Process m ()

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

usingResourceWithPriority

Arguments

:: Resource m

the resource we are going to request for and then release in the end

-> Double

the priority (the less value has a higher priority)

-> Process m a

the action we are going to apply having the resource

-> Process m a

the result of the action

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

Arguments

:: Resource m

the resource

-> Int

the increment for the resource count

-> 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

Arguments

:: Resource m

the resource

-> Int

the decrement for the resource count

-> Event m ()

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

alterResourceCount

Arguments

:: Resource m

the resource

-> Int

a change of the resource count

-> Event m ()

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

Instances

MonadResource IO

The IO monad is an instance of MonadResource.

Defined in Simulation.Aivika.IO.Resource.Preemption.Base

Associated Types

data Resource IO :: *

Methods

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

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

resourceCount :: Resource IO -> Event IO Int

resourceMaxCount :: Resource IO -> Maybe Int

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

releaseResource :: Resource IO -> Process IO ()

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

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

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

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