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fix the nondeterminism from using hashmap. doh.

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This commit is contained in:
Dustin Carlino 2018-04-16 17:21:25 -07:00
parent 93245a79ca
commit 9e1c5ffc52
2 changed files with 12 additions and 6 deletions
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2
sim/src/common.rs
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@ -14,7 +14,7 @@
use dimensioned::si;
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, Serialize, Deserialize)]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
pub struct CarID(pub usize);
use std;

16
sim/src/straw_model.rs
View File

@ -25,7 +25,7 @@ use graphics::math::Vec2d;
use map_model::{Map, Pt2D, RoadID, TurnID};
use multimap::MultiMap;
use rand::{NewRng, Rng, SeedableRng, XorShiftRng};
use std::collections::{HashMap, HashSet};
use std::collections::{BTreeMap, HashSet};
use std::f64;
use std::fs::File;
use std::io::{Error, Read, Write};
@ -205,7 +205,7 @@ impl SimQueue {
// TODO it'd be cool to contribute tooltips (like number of cars currently here, capacity) to
// tooltip
fn room_at_end(&self, time: Tick, cars: &HashMap<CarID, Car>) -> bool {
fn room_at_end(&self, time: Tick, cars: &BTreeMap<CarID, Car>) -> bool {
if self.cars_queue.is_empty() {
return true;
}
@ -219,7 +219,7 @@ impl SimQueue {
>= FOLLOWING_DISTANCE / SPEED_LIMIT
}
fn reset(&mut self, ids: &Vec<CarID>, cars: &HashMap<CarID, Car>) {
fn reset(&mut self, ids: &Vec<CarID>, cars: &BTreeMap<CarID, Car>) {
let old_queue = self.cars_queue.clone();
assert!(ids.len() <= self.capacity);
@ -285,7 +285,9 @@ pub struct Sim {
// captures the RNG), this should be OK for now.
#[derivative(PartialEq = "ignore")] rng: XorShiftRng,
// TODO investigate slot map-like structures for performance
cars: HashMap<CarID, Car>,
// Using BTreeMap instead of HashMap so iteration is deterministic. Should be able to relax
// this later after step() doesnt need a RNG.
cars: BTreeMap<CarID, Car>,
roads: Vec<SimQueue>,
turns: Vec<SimQueue>,
intersections: Vec<IntersectionPolicy>,
@ -316,7 +318,7 @@ impl Sim {
rng,
intersections,
cars: HashMap::new(),
cars: BTreeMap::new(),
roads: map.all_roads()
.iter()
.map(|r| SimQueue::new(On::Road(r.id), geom_map))
@ -384,6 +386,10 @@ impl Sim {
// room now. It's important to query has_room_now here using the previous, fixed state of
// the world. If we did it in the next loop, then order of updates would matter for more
// than just conflict resolution.
//
// Note that since this uses RNG right now, it's only deterministic if iteration order is!
// So can't be concurrent and use RNG. Could have a RNG per car or something later if we
// really needed both.
let mut requested_moves: Vec<(CarID, Action)> = Vec::new();
for c in self.cars.values() {
requested_moves.push((