Struct PreemptiveScheduling 

pub struct PreemptiveScheduling { /* private fields */ }

The Preemptive Scheduling problem.

Given n tasks with processing lengths l(0), ..., l(n-1), m identical processors, and a set of precedence constraints, find a preemptive schedule that minimizes the makespan.

Tasks may be interrupted and resumed at later time slots (preemption). A configuration is a binary vector of length n × D_max where D_max = sum of all lengths is the worst-case makespan.

config[t * D_max + u] = 1 means task t is processed at time slot u.

A valid schedule satisfies:

• Each task t is active in exactly l(t) time slots.
• At most m tasks are active at any time slot.
• For each precedence (pred, succ), the last active slot of pred is strictly less than the first active slot of succ.

The makespan is max_t (last active slot of t + 1).

Example

use problemreductions::models::misc::PreemptiveScheduling;
use problemreductions::Problem;

let problem = PreemptiveScheduling::new(vec![2, 1], 2, vec![]);
// D_max = 3, config length = 2 * 3 = 6
// task 0 active at slots 0,1; task 1 active at slot 0
let config = vec![1, 1, 0, 1, 0, 0];
assert_eq!(problem.evaluate(&config), problemreductions::types::Min(Some(2)));

Implementations

impl PreemptiveScheduling

pub fn new( lengths: Vec<usize>, num_processors: usize, precedences: Vec<(usize, usize)>, ) -> Self

Create a new Preemptive Scheduling instance.

Arguments

• lengths - Processing length l(t) for each task (must be positive)
• num_processors - Number of identical processors m (must be positive)
• precedences - Pairs (pred, succ): task pred must finish before task succ starts

Panics

Panics if any length is zero, num_processors is zero, or any precedence index is out of range.

pub fn num_tasks(&self) -> usize

Get the number of tasks.

pub fn num_processors(&self) -> usize

Get the number of processors.

pub fn num_precedences(&self) -> usize

Get the number of precedence constraints.

pub fn lengths(&self) -> &[usize]

Get the processing lengths.

pub fn precedences(&self) -> &[(usize, usize)]

Get the precedence constraints.

pub fn d_max(&self) -> usize

Compute D_max = sum of all task lengths (worst-case makespan).

Trait Implementations

impl Clone for PreemptiveScheduling

fn clone(&self) -> PreemptiveScheduling

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PreemptiveScheduling

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for PreemptiveScheduling

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Problem for PreemptiveScheduling

const NAME: &'static str = "PreemptiveScheduling"

Base name of this problem type (e.g., “MaximumIndependentSet”).

type Value = Min<usize>

The evaluation value type.

fn variant() -> Vec<(&'static str, &'static str)>

Returns variant attributes derived from type parameters.

fn dims(&self) -> Vec<usize>

Configuration space dimensions. Each entry is the cardinality of that variable.

fn evaluate(&self, config: &[usize]) -> Min<usize>

Evaluate the problem on a configuration.

fn num_variables(&self) -> usize

Number of variables (derived from dims).

fn problem_type() -> ProblemType

Look up this problem’s catalog entry.

impl ReduceTo<ILP<i32>> for PreemptiveScheduling

type Result = ReductionPSToILP

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<PreemptiveScheduling> for KSatisfiability<K3>

type Result = Reduction3SATToPreemptiveScheduling

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl Serialize for PreemptiveScheduling

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl DeclaredVariant for PreemptiveScheduling