moving RNG helpers from sim to abstutil

abstutil/Cargo.toml

@@ -6,7 +6,9 @@ authors = ["Dustin Carlino <dabreegster@gmail.com>"]
 [dependencies]
 log = "0.4.5"
 multimap = "0.4.0"
+rand = { version = "0.5.1", features = ["serde1"] }
 serde = "1.0"
 serde_cbor = "0.8.2"
+serde_derive = "1.0"
 serde_json = "1.0"
 yansi = "0.4.0"

abstutil/src/clone.rs

@@ -1,4 +1,5 @@
 use std::any::Any;
+use WeightedUsizeChoice;
 
 // Trick to make a cloneable Any from
 // https://stackoverflow.com/questions/30353462/how-to-clone-a-struct-storing-a-boxed-trait-object/30353928#30353928.
@@ -34,3 +35,4 @@ impl Cloneable for usize {}
 impl Cloneable for f64 {}
 impl Cloneable for String {}
 impl Cloneable for (String, Box<Cloneable>) {}
+impl Cloneable for WeightedUsizeChoice {}

abstutil/src/lib.rs

@@ -1,7 +1,10 @@
 extern crate log;
 extern crate multimap;
+extern crate rand;
 extern crate serde;
 extern crate serde_cbor;
+#[macro_use]
+extern crate serde_derive;
 extern crate serde_json;
 extern crate yansi;
 
@@ -11,6 +14,7 @@ mod collections;
 mod error;
 mod io;
 mod logs;
+mod random;
 mod time;
 
 pub use abst_multimap::MultiMap;
@@ -23,6 +27,7 @@ pub use io::{
     write_json, FileWithProgress,
 };
 pub use logs::{format_log_record, LogAdapter};
+pub use random::{fork_rng, WeightedUsizeChoice};
 pub use time::{elapsed_seconds, Timer};
 
 const PROGRESS_FREQUENCY_SECONDS: f64 = 0.2;

abstutil/src/random.rs

@@ -0,0 +1,41 @@
+use rand::distributions::{Distribution, Weighted, WeightedChoice};
+use rand::{RngCore, SeedableRng, XorShiftRng};
+
+// Need to explain this trick -- basically keeps consistency between two different simulations when
+// each one might make slightly different sequences of calls to the RNG.
+pub fn fork_rng(base_rng: &mut XorShiftRng) -> XorShiftRng {
+    XorShiftRng::from_seed([base_rng.next_u32() as u8; 16])
+}
+
+// Represents the probability of sampling 0, 1, 2, 3... The sum can be anything.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct WeightedUsizeChoice {
+    pub weights: Vec<u32>,
+}
+
+impl WeightedUsizeChoice {
+    pub fn parse(string: &str) -> Option<WeightedUsizeChoice> {
+        let parts: Vec<&str> = string.split(",").collect();
+        if parts.is_empty() {
+            return None;
+        }
+        let mut weights: Vec<u32> = Vec::new();
+        for x in parts.into_iter() {
+            let x = x.parse::<u32>().ok()?;
+            weights.push(x);
+        }
+        Some(WeightedUsizeChoice { weights })
+    }
+
+    pub fn sample(&self, rng: &mut XorShiftRng) -> u32 {
+        let mut items: Vec<Weighted<u32>> = self
+            .weights
+            .iter()
+            .enumerate()
+            .map(|(idx, pr)| Weighted {
+                weight: *pr,
+                item: idx as u32,
+            }).collect();
+        WeightedChoice::new(&mut items).sample(rng)
+    }
+}

editor/src/plugins/mod.rs

@@ -28,14 +28,12 @@ pub mod turn_cycler;
 pub mod warp;
 
 use abstutil;
+use abstutil::WeightedUsizeChoice;
 use downcast::Any;
 use ezgui::{Color, GfxCtx, WrappedWizard};
 use map_model::{IntersectionID, Map};
 use objects::{Ctx, ID};
-use sim::{
-    ABTest, Neighborhood, NeighborhoodBuilder, OriginDestination, Scenario, Tick,
-    WeightedUsizeChoice,
-};
+use sim::{ABTest, Neighborhood, NeighborhoodBuilder, OriginDestination, Scenario, Tick};
 use ui::PluginCtx;
 
 pub trait Plugin: Any {

sim/src/helpers.rs

@@ -1,3 +1,4 @@
+use abstutil::WeightedUsizeChoice;
 use control::ControlMap;
 use driving::DrivingGoal;
 use map_model::{BuildingID, BusRoute, BusStopID, LaneID, Map, RoadID};
@@ -5,7 +6,7 @@ use std::collections::{BTreeSet, VecDeque};
 use walking::SidewalkSpot;
 use {
     BorderSpawnOverTime, CarID, Event, OriginDestination, PedestrianID, RouteID, Scenario,
-    SeedParkedCars, Sim, SpawnOverTime, Tick, WeightedUsizeChoice,
+    SeedParkedCars, Sim, SpawnOverTime, Tick,
 };
 
 // Helpers to run the sim

sim/src/lib.rs

@@ -58,7 +58,6 @@ pub use make::{
     OriginDestination, Scenario, SeedParkedCars, SimFlags, SpawnOverTime,
 };
 use map_model::{BuildingID, LaneID, Trace, TurnID};
-use rand::{RngCore, SeedableRng, XorShiftRng};
 pub use sim::{Benchmark, Sim, Summary};
 pub use stats::SimStats;
 use std::fmt;
@@ -335,42 +334,3 @@ impl Cloneable for Scenario {}
 impl Cloneable for Tick {}
 impl Cloneable for MapEdits {}
 impl Cloneable for ABTest {}
-impl Cloneable for WeightedUsizeChoice {}
-
-fn fork_rng(base_rng: &mut XorShiftRng) -> XorShiftRng {
-    XorShiftRng::from_seed([base_rng.next_u32() as u8; 16])
-}
-
-// Represents the probability of sampling 0, 1, 2, 3... The sum can be anything.
-#[derive(Clone, Debug, Serialize, Deserialize)]
-pub struct WeightedUsizeChoice {
-    weights: Vec<u32>,
-}
-
-impl WeightedUsizeChoice {
-    pub fn parse(string: &str) -> Option<WeightedUsizeChoice> {
-        let parts: Vec<&str> = string.split(",").collect();
-        if parts.is_empty() {
-            return None;
-        }
-        let mut weights: Vec<u32> = Vec::new();
-        for x in parts.into_iter() {
-            let x = x.parse::<u32>().ok()?;
-            weights.push(x);
-        }
-        Some(WeightedUsizeChoice { weights })
-    }
-}
-
-fn weighted_sample(choices: &WeightedUsizeChoice, rng: &mut XorShiftRng) -> u32 {
-    use rand::distributions::{Distribution, Weighted, WeightedChoice};
-    let mut items: Vec<Weighted<u32>> = choices
-        .weights
-        .iter()
-        .enumerate()
-        .map(|(idx, pr)| Weighted {
-            weight: *pr,
-            item: idx as u32,
-        }).collect();
-    WeightedChoice::new(&mut items).sample(rng)
-}

sim/src/make/scenario.rs

@@ -1,11 +1,12 @@
 use abstutil;
+use abstutil::WeightedUsizeChoice;
 use driving::DrivingGoal;
 use map_model::{BuildingID, IntersectionID, LaneType, Map, RoadID};
 use rand::Rng;
 use rand::XorShiftRng;
 use std::collections::{BTreeSet, HashMap, HashSet};
 use walking::SidewalkSpot;
-use {CarID, Neighborhood, Sim, Tick, WeightedUsizeChoice};
+use {CarID, Neighborhood, Sim, Tick};
 
 #[derive(Clone, Serialize, Deserialize, Debug)]
 pub struct Scenario {

sim/src/spawn.rs

@@ -1,4 +1,4 @@
-use abstutil::elapsed_seconds;
+use abstutil::{elapsed_seconds, fork_rng, WeightedUsizeChoice};
 use dimensioned::si;
 use driving::{CreateCar, DrivingGoal, DrivingSimState};
 use kinematics::Vehicle;
@@ -12,8 +12,7 @@ use transit::TransitSimState;
 use trips::{TripLeg, TripManager};
 use walking::{SidewalkSpot, WalkingSimState};
 use {
-    fork_rng, weighted_sample, AgentID, CarID, Distance, Event, ParkedCar, ParkingSpot,
-    PedestrianID, RouteID, Tick, TripID, WeightedUsizeChoice,
+    AgentID, CarID, Distance, Event, ParkedCar, ParkingSpot, PedestrianID, RouteID, Tick, TripID,
 };
 
 #[derive(Serialize, Deserialize, PartialEq, Eq, Debug)]
@@ -329,7 +328,7 @@ impl Spawner {
 
         let mut new_cars = 0;
         for b in owner_buildings {
-            for _ in 0..weighted_sample(&cars_per_building, base_rng) {
+            for _ in 0..cars_per_building.sample(base_rng) {
                 if let Some(spot) =
                     find_spot_near_building(*b, &mut open_spots_per_road, neighborhoods_roads, map)
                 {