Copyright	Copyright (c) 2009-2017 David Sorokin <david.sorokin@gmail.com>
License	BSD3
Maintainer	David Sorokin <david.sorokin@gmail.com>
Stability	experimental
Safe Haskell	Safe-Inferred
Language	Haskell2010

Simulation.Aivika.Trans.Resource.Preemption.Base

Description

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.

Synopsis

class MonadDES m => MonadResource m where
- data Resource m
- newResource :: Int -> Simulation m (Resource m)
- newResourceWithMaxCount :: Int -> Maybe Int -> Simulation m (Resource m)
- resourceCount :: Resource m -> Event m Int
- resourceMaxCount :: Resource m -> Maybe Int
- requestResourceWithPriority :: Resource m -> Double -> Process m ()
- releaseResource :: Resource m -> Process m ()
- usingResourceWithPriority :: Resource m -> Double -> Process m a -> Process m a
- incResourceCount :: Resource m -> Int -> Event m ()
- decResourceCount :: Resource m -> Int -> Event m ()
- alterResourceCount :: Resource m -> Int -> Event m ()

Documentation

class MonadDES m => MonadResource m where Source #

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

Associated Types

data Resource m Source #

Represents a preemptible resource.

Methods

newResource Source #

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 Source #

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 Source #

Return the current count of the resource.

resourceMaxCount :: Resource m -> Maybe Int Source #

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

requestResourceWithPriority Source #

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 Source #

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 Source #

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 Source #

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 Source #

Arguments