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#[cfg(test)]
#[path = "../../../../tests/unit/solver/mutation/ruin/worst_jobs_removal_test.rs"]
mod worst_jobs_removal_test;
use super::*;
use crate::construction::heuristics::{InsertionContext, RouteContext};
use crate::models::common::{Cost, Timestamp};
use crate::models::problem::{Actor, Job, TransportCost};
use crate::models::solution::Activity;
use crate::solver::RefinementContext;
use crate::utils::parallel_collect;
use hashbrown::{HashMap, HashSet};
use rand::prelude::*;
use std::cmp::Ordering::Less;
use std::iter::once;
use std::sync::{Arc, RwLock};
pub struct WorstJobRemoval {
limit: JobRemovalLimit,
worst_skip: usize,
}
impl WorstJobRemoval {
pub fn new(worst_skip: usize, limit: JobRemovalLimit) -> Self {
Self { limit, worst_skip }
}
}
impl Default for WorstJobRemoval {
fn default() -> Self {
Self::new(4, JobRemovalLimit::default())
}
}
impl Ruin for WorstJobRemoval {
fn run(&self, _refinement_ctx: &RefinementContext, mut insertion_ctx: InsertionContext) -> InsertionContext {
let problem = insertion_ctx.problem.clone();
let random = insertion_ctx.random.clone();
let can_remove_job = |job: &Job| -> bool {
let solution = &insertion_ctx.solution;
!solution.locked.contains(job) && !solution.unassigned.contains_key(job)
};
let mut route_jobs = get_route_jobs(&insertion_ctx.solution);
let mut routes_savings = get_routes_cost_savings(&insertion_ctx);
let removed_jobs: RwLock<HashSet<Job>> = RwLock::new(HashSet::default());
routes_savings.shuffle(&mut insertion_ctx.random.get_rng());
let affected = get_removal_chunk_size(&insertion_ctx, &self.limit);
routes_savings.iter().take_while(|_| removed_jobs.read().unwrap().len() < affected).for_each(
|(rc, savings)| {
let skip = savings.len().min(random.uniform_int(0, self.worst_skip as i32) as usize);
let worst = savings.iter().filter(|(job, _)| can_remove_job(job)).nth(skip);
if let Some((job, _)) = worst {
let remove = random.uniform_int(self.limit.min as i32, self.limit.max as i32) as usize;
once(job.clone())
.chain(
problem
.jobs
.neighbors(rc.route.actor.vehicle.profile, &job, Timestamp::default())
.filter(|(_, cost)| *cost > 0.)
.map(|(job, _)| job)
.cloned(),
)
.filter(|job| can_remove_job(job))
.take(remove)
.for_each(|job| {
if let Some(rc) = route_jobs.get_mut(&job) {
if rc.route_mut().tour.remove(&job) {
removed_jobs.write().unwrap().insert(job);
}
}
});
}
},
);
removed_jobs.write().unwrap().iter().for_each(|job| insertion_ctx.solution.required.push(job.clone()));
insertion_ctx
}
}
fn get_routes_cost_savings(insertion_ctx: &InsertionContext) -> Vec<(RouteContext, Vec<(Job, Cost)>)> {
parallel_collect(&insertion_ctx.solution.routes, |rc| {
let actor = rc.route.actor.as_ref();
let mut savings: Vec<(Job, Cost)> = rc
.route
.tour
.all_activities()
.as_slice()
.windows(3)
.fold(HashMap::<Job, Cost>::default(), |mut acc, iter| match iter {
[start, eval, end] => {
let savings = get_cost_savings(actor, start, eval, end, &insertion_ctx.problem.transport);
let job = eval.retrieve_job().unwrap_or_else(|| panic!("Unexpected activity without job"));
*acc.entry(job).or_insert(0.) += savings;
acc
}
_ => panic!("Unexpected activity window"),
})
.drain()
.collect();
savings.sort_by(|(_, a), (_, b)| b.partial_cmp(a).unwrap_or(Less));
(rc.clone(), savings)
})
}
#[inline(always)]
fn get_cost_savings(
actor: &Actor,
start: &Activity,
middle: &Activity,
end: &Activity,
transport: &Arc<dyn TransportCost + Send + Sync>,
) -> Cost {
get_cost(actor, start, middle, transport) + get_cost(actor, middle, end, transport)
- get_cost(actor, start, end, transport)
}
#[inline(always)]
fn get_cost(actor: &Actor, from: &Activity, to: &Activity, transport: &Arc<dyn TransportCost + Send + Sync>) -> Cost {
transport.cost(actor, from.place.location, to.place.location, from.schedule.departure)
}