variable simulation time

battlesnake/src/logic.rs

@@ -11,9 +11,14 @@
 // For more info see docs.battlesnake.com
 
 use core::f64;
-use std::collections::BTreeMap;
+use std::{
+    cell::Cell,
+    collections::{BTreeMap, HashMap},
+    sync::{Arc, LazyLock, Mutex},
+    time::{Duration, Instant},
+};
 
-use log::info;
+use log::{error, info};
 use ordered_float::OrderedFloat;
 use serde_json::{json, Value};
 
@@ -101,41 +106,92 @@ pub fn info() -> Value {
     })
 }
 
+#[derive(Debug, PartialEq, Eq, Clone)]
+struct GameInfo {
+    calculation_time: Cell<Duration>,
+    token_mapping: Arc<BTreeMap<String, SnakeToken>>,
+    my_token: SnakeToken,
+}
+
+static GAME_INFOS: LazyLock<Mutex<HashMap<(String, String), GameInfo>>> =
+    LazyLock::new(|| Mutex::new(HashMap::new()));
+
 // start is called when your Battlesnake begins a game
-pub fn start(_game: &Game, _turn: i32, _board: &Board, _you: &Battlesnake) {
+pub fn start(game: &Game, _turn: i32, board: &Board, you: &Battlesnake) {
     info!("GAME START");
+    let token_mapping = Arc::new(SnakeToken::from_board(board));
+    let my_token = token_mapping[&you.id];
+    let Ok(mut game_infos) = GAME_INFOS.lock() else {
+        error!("unable to lock game infos");
+        return;
+    };
+    game_infos.insert(
+        (game.id.clone(), you.id.clone()),
+        GameInfo {
+            calculation_time: Cell::new(Duration::from_millis(50)),
+            token_mapping,
+            my_token,
+        },
+    );
 }
 
 // end is called when your Battlesnake finishes a game
-pub fn end(_game: &Game, _turn: i32, _board: &Board, _you: &Battlesnake) {
+pub fn end(game: &Game, _turn: i32, _board: &Board, you: &Battlesnake) {
     info!("GAME OVER");
+    let Ok(mut game_infos) = GAME_INFOS.lock() else {
+        error!("unable to lock game infos");
+        return;
+    };
+    game_infos.remove(&(game.id.clone(), you.id.clone()));
 }
 
 // move is called on every turn and returns your next move
 // Valid moves are "up", "down", "left", or "right"
 // See https://docs.battlesnake.com/api/example-move for available data
 pub fn get_move(game: &Game, turn: i32, board: &Board, you: &Battlesnake) -> Option<Action> {
-    let token_map = SnakeToken::from_board(board);
+    let start = Instant::now();
+    let game_info = GAME_INFOS
+        .lock()
+        .ok()
+        .and_then(|guard| guard.get(&(game.id.clone(), you.id.clone())).cloned())
+        .unwrap_or_else(|| {
+            let token_mapping = Arc::new(SnakeToken::from_board(board));
+            let my_token = token_mapping[&you.id];
+            GameInfo {
+                calculation_time: Cell::new(Duration::from_millis(50)),
+                token_mapping,
+                my_token,
+            }
+        });
+
+    // do some latency compensation
+    game_info.calculation_time.set(
+        game_info.calculation_time.get()
+            + Duration::from_millis(
+                u64::from(
+                    game.timeout * 3 / 4 - you.latency.parse().unwrap_or(game.timeout * 3 / 4),
+                ) / 3,
+            ),
+    );
+
     let board = simulation::Board::from_game_board(
         board,
-        &token_map,
+        &game_info.token_mapping,
         turn,
         game.ruleset.settings.food_spawn_chance,
         game.ruleset.settings.minimum_food,
     );
 
-    let my_token = token_map[&you.id];
-
     let mut tree = Node::default();
 
-    for _ in 0..300 {
+    while start.elapsed() < game_info.calculation_time.get() {
         let mut board = board.clone();
         tree.monte_carlo_step(&mut board);
     }
 
-    let actions = tree.child_statistics.entry(my_token).or_default();
+    let actions = tree.child_statistics.entry(game_info.my_token).or_default();
 
-    info!("actions: {actions:?}");
+    info!("actions {}: {actions:?}", you.name);
 
     #[allow(clippy::cast_precision_loss)]
     let chosen = actions
@@ -143,7 +199,11 @@ pub fn get_move(game: &Game, turn: i32, board: &Board, you: &Battlesnake) -> Opt
         .max_by_key(|(_, stat)| OrderedFloat(stat.won as f64 / stat.played as f64))
         .map(|(direction, _)| *direction)?;
 
-    info!("DIRECTION {}: {:?}", turn, chosen);
+    info!(
+        "DIRECTION {turn}: {chosen:?} after {}ms ({})",
+        start.elapsed().as_millis(),
+        you.name,
+    );
     Some(Action {
         r#move: chosen,
         shout: None,
@@ -186,12 +246,9 @@ impl Node {
 
             let actions = possible_actions
                 .iter()
-                .map(|(token, actions)| {
+                .filter_map(|(token, actions)| {
                     let statistics = self.child_statistics.entry(*token).or_default();
-                    let selected = actions
-                        .iter()
-                        .copied()
-                        .max_by_key(|direction| {
+                    let selected = actions.iter().copied().max_by_key(|direction| {
                         let statistics = statistics.entry(*direction).or_default();
                         if statistics.played == 0 {
                             return OrderedFloat(f64::INFINITY);
@@ -201,13 +258,11 @@ impl Node {
                         #[allow(clippy::cast_precision_loss)]
                         let exploration = f64::consts::SQRT_2
                             * f64::sqrt(
-                                    f64::ln(self.statistic.played as f64)
-                                        / statistics.played as f64,
+                                f64::ln(self.statistic.played as f64) / statistics.played as f64,
                             );
                         OrderedFloat(exploitation + exploration)
-                        })
-                        .unwrap_or_default();
-                    (*token, selected)
+                    })?;
+                    Some((*token, selected))
                 })
                 .collect();
 

battlesnake/src/main.rs

@@ -19,23 +19,11 @@ const MAX_HEALTH: i32 = 100;
 // See https://docs.battlesnake.com/api
 
 #[derive(
-    Debug,
-    PartialEq,
-    Eq,
-    PartialOrd,
-    Ord,
-    Hash,
-    Clone,
-    Copy,
-    Deserialize,
-    Serialize,
-    Sequence,
-    Default,
+    Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Deserialize, Serialize, Sequence,
 )]
 #[serde(rename_all = "lowercase")]
 pub enum Direction {
     /// Move left (-x)
-    #[default]
     Left,
     /// Move up (+y)
     Up,

battlesnake/src/simulation.rs

@@ -92,7 +92,7 @@ impl Board {
     pub fn simulate_actions(&mut self, actions: &BTreeMap<SnakeToken, Direction>) {
         // move snakes
         for (token, snake) in &mut self.snakes {
-            snake.perform_action(actions.get(token).copied().unwrap_or_default());
+            snake.perform_action(actions.get(token).copied().unwrap_or(Direction::Up));
         }
 
         // feed snakes
@@ -170,7 +170,7 @@ impl Board {
                             .iter()
                             .choose(&mut rand::thread_rng())
                             .copied()
-                            .unwrap_or_default(),
+                            .unwrap_or(Direction::Up),
                     )
                 })
                 .collect();