Add a method to the API to modify a scenario. No callers/tests yet.

book/src/dev/api.md

@@ -23,6 +23,9 @@ are missing, etc. A summary of the commands available so far:
   - **GET /sim/reset**: Reset all map edits and the simulation state. The trips
     that will run don't change; they're determined by the scenario file you
     initially pass to `headless`.
+  - **POST /sim/load**: Switch the scenario being simulated. Takes a
+    [SimFlags](https://dabreegster.github.io/abstreet/rustdoc/sim/struct.SimFlags.html)
+    as a JSON POST body.
   - **GET /sim/get-time**: Returns the current simulation time.
   - **GET /sim/goto-time?t=06:30:00**: Simulate until 6:30 AM. If the time you
     specify is before the current time, you have to call **/sim/reset** first.

headless/src/main.rs

@@ -29,7 +29,6 @@ use std::sync::RwLock;
 lazy_static::lazy_static! {
     static ref MAP: RwLock<Map> = RwLock::new(Map::blank());
     static ref SIM: RwLock<Sim> = RwLock::new(Sim::new(&Map::blank(), SimOptions::new("tmp"), &mut Timer::throwaway()));
-    // TODO Readonly?
     static ref FLAGS: RwLock<SimFlags> = RwLock::new(SimFlags::for_test("tmp"));
 }
 
@@ -98,6 +97,16 @@ fn handle_command(
             *sim = new_sim;
             Ok(format!("sim reloaded"))
         }
+        "/sim/load" => {
+            let flags: SimFlags = abstutil::from_json(body)?;
+            *FLAGS.write().unwrap() = flags;
+
+            // Also reset
+            let (new_map, new_sim, _) = FLAGS.read().unwrap().load(&mut Timer::new("reset sim"));
+            *map = new_map;
+            *sim = new_sim;
+            Ok(format!("flags changed and sim reloaded"))
+        }
         "/sim/get-time" => Ok(sim.time().to_string()),
         "/sim/goto-time" => {
             let t = Time::parse(&params["t"])?;
@@ -126,7 +135,7 @@ fn handle_command(
             scenario.people = ExternalPerson::import(map, vec![input])?;
             let id = PersonID(sim.get_all_people().len());
             scenario.people[0].id = id;
-            let mut rng = SimFlags::for_test("oneshot").make_rng();
+            let mut rng = FLAGS.read().unwrap().make_rng();
             scenario.instantiate(sim, map, &mut rng, &mut Timer::throwaway());
             Ok(format!("{} created", id))
         }

sim/src/make/load.rs

@@ -1,15 +1,19 @@
-use crate::{AlertHandler, Scenario, Sim, SimOptions};
+use crate::{AlertHandler, Scenario, ScenarioModifier, Sim, SimOptions};
 use abstutil::CmdArgs;
 use map_model::{Map, MapEdits};
 use rand::SeedableRng;
 use rand_xorshift::XorShiftRng;
+use serde::Deserialize;
 
 const RNG_SEED: u8 = 42;
 
-#[derive(Clone)]
+#[derive(Clone, Deserialize)]
 pub struct SimFlags {
     pub load: String,
+    pub modifiers: Vec<ScenarioModifier>,
+    #[serde(skip_deserializing)]
     pub rng_seed: u8,
+    #[serde(skip_deserializing)]
     pub opts: SimOptions,
 }
 
@@ -23,6 +27,7 @@ impl SimFlags {
             load: args
                 .optional_free()
                 .unwrap_or_else(|| abstutil::path_map("montlake")),
+            modifiers: Vec::new(),
             rng_seed,
             opts: SimOptions {
                 run_name: args
@@ -61,6 +66,7 @@ impl SimFlags {
     pub fn synthetic_test(map: &str, run_name: &str) -> SimFlags {
         SimFlags {
             load: abstutil::path_map(map),
+            modifiers: Vec::new(),
             rng_seed: RNG_SEED,
             opts: SimOptions::new(run_name),
         }
@@ -103,10 +109,15 @@ impl SimFlags {
                 self.load
             ));
 
-            let scenario: Scenario = abstutil::read_binary(self.load.clone(), timer);
+            let mut scenario: Scenario = abstutil::read_binary(self.load.clone(), timer);
 
             let map = Map::new(abstutil::path_map(&scenario.map_name), timer);
 
+            let mut modifier_rng = self.make_rng();
+            for m in &self.modifiers {
+                scenario = m.apply(&map, scenario, &mut modifier_rng);
+            }
+
             if opts.run_name == "unnamed" {
                 opts.run_name = scenario.scenario_name.clone();
             }

sim/src/make/modifier.rs

@@ -4,9 +4,10 @@ use geom::{Duration, Time};
 use map_model::Map;
 use rand::Rng;
 use rand_xorshift::XorShiftRng;
+use serde::Deserialize;
 use std::collections::BTreeSet;
 
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone)]
+#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Deserialize)]
 pub enum ScenarioModifier {
     RepeatDays(usize),
     CancelPeople(usize),

sim/src/sim.rs

@@ -76,6 +76,12 @@ pub struct SimOptions {
     pub live_map_edits: bool,
 }
 
+impl std::default::Default for SimOptions {
+    fn default() -> SimOptions {
+        SimOptions::new("tmp")
+    }
+}
+
 #[derive(Clone)]
 pub enum AlertHandler {
     // Just print the alert to STDOUT