add simulation benchmarks

Cargo.lock

@@ -26,6 +26,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "anes"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
+
 [[package]]
 name = "anstream"
 version = "0.6.18"
@@ -173,6 +179,7 @@ version = "2.0.0"
 dependencies = [
  "axum",
  "bitvec",
+ "criterion",
  "enum-iterator",
  "env_logger",
  "log",
@@ -202,6 +209,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "bumpalo"
+version = "3.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79296716171880943b8470b5f8d03aa55eb2e645a4874bdbb28adb49162e012c"
+
 [[package]]
 name = "byteorder"
 version = "1.5.0"
@@ -214,12 +227,70 @@ version = "1.9.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "325918d6fe32f23b19878fe4b34794ae41fc19ddbe53b10571a4874d44ffd39b"
 
+[[package]]
+name = "cast"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "ciborium"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42e69ffd6f0917f5c029256a24d0161db17cea3997d185db0d35926308770f0e"
+dependencies = [
+ "ciborium-io",
+ "ciborium-ll",
+ "serde",
+]
+
+[[package]]
+name = "ciborium-io"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05afea1e0a06c9be33d539b876f1ce3692f4afea2cb41f740e7743225ed1c757"
+
+[[package]]
+name = "ciborium-ll"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57663b653d948a338bfb3eeba9bb2fd5fcfaecb9e199e87e1eda4d9e8b240fd9"
+dependencies = [
+ "ciborium-io",
+ "half",
+]
+
+[[package]]
+name = "clap"
+version = "4.5.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "769b0145982b4b48713e01ec42d61614425f27b7058bda7180a3a41f30104796"
+dependencies = [
+ "clap_builder",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.5.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b26884eb4b57140e4d2d93652abfa49498b938b3c9179f9fc487b0acc3edad7"
+dependencies = [
+ "anstyle",
+ "clap_lex",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
+
 [[package]]
 name = "colorchoice"
 version = "1.0.3"
@@ -235,6 +306,42 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "criterion"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2b12d017a929603d80db1831cd3a24082f8137ce19c69e6447f54f5fc8d692f"
+dependencies = [
+ "anes",
+ "cast",
+ "ciborium",
+ "clap",
+ "criterion-plot",
+ "is-terminal",
+ "itertools",
+ "num-traits",
+ "once_cell",
+ "oorandom",
+ "plotters",
+ "rayon",
+ "regex",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "tinytemplate",
+ "walkdir",
+]
+
+[[package]]
+name = "criterion-plot"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b50826342786a51a89e2da3a28f1c32b06e387201bc2d19791f622c673706b1"
+dependencies = [
+ "cast",
+ "itertools",
+]
+
 [[package]]
 name = "crossbeam-deque"
 version = "0.8.6"
@@ -260,6 +367,12 @@ version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
+[[package]]
+name = "crunchy"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a81dae078cea95a014a339291cec439d2f232ebe854a9d672b796c6afafa9b7"
+
 [[package]]
 name = "crypto-common"
 version = "0.1.6"
@@ -458,12 +571,28 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "half"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
+dependencies = [
+ "cfg-if",
+ "crunchy",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.15.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bf151400ff0baff5465007dd2f3e717f3fe502074ca563069ce3a6629d07b289"
 
+[[package]]
+name = "hermit-abi"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
+
 [[package]]
 name = "http"
 version = "1.2.0"
@@ -562,18 +691,48 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "is-terminal"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "261f68e344040fbd0edea105bef17c66edf46f984ddb1115b775ce31be948f4b"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"
 
+[[package]]
+name = "js-sys"
+version = "0.3.77"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cfaf33c695fc6e08064efbc1f72ec937429614f25eef83af942d0e227c3a28f"
+dependencies = [
+ "once_cell",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.169"
@@ -641,6 +800,15 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "object"
 version = "0.36.7"
@@ -656,6 +824,12 @@ version = "1.20.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1261fe7e33c73b354eab43b1273a57c8f967d0391e80353e51f764ac02cf6775"
 
+[[package]]
+name = "oorandom"
+version = "11.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b410bbe7e14ab526a0e86877eb47c6996a2bd7746f027ba551028c925390e4e9"
+
 [[package]]
 name = "percent-encoding"
 version = "2.3.1"
@@ -674,6 +848,34 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "plotters"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aeb6f403d7a4911efb1e33402027fc44f29b5bf6def3effcc22d7bb75f2b747"
+dependencies = [
+ "num-traits",
+ "plotters-backend",
+ "plotters-svg",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "plotters-backend"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df42e13c12958a16b3f7f4386b9ab1f3e7933914ecea48da7139435263a4172a"
+
+[[package]]
+name = "plotters-svg"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51bae2ac328883f7acdfea3d66a7c35751187f870bc81f94563733a154d7a670"
+dependencies = [
+ "plotters-backend",
+]
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.20"
@@ -804,6 +1006,15 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"
 
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.217"
@@ -943,6 +1154,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tinytemplate"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be4d6b5f19ff7664e8c98d03e2139cb510db9b0a60b55f8e8709b689d939b6bc"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "tokio"
 version = "1.43.0"
@@ -1091,12 +1312,99 @@ version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
 [[package]]
 name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
 
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1edc8929d7499fc4e8f0be2262a241556cfc54a0bea223790e71446f2aab1ef5"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "rustversion",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f0a0651a5c2bc21487bde11ee802ccaf4c51935d0d3d42a6101f98161700bc6"
+dependencies = [
+ "bumpalo",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fe63fc6d09ed3792bd0897b314f53de8e16568c2b3f7982f468c0bf9bd0b407"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ae87ea40c9f689fc23f209965b6fb8a99ad69aeeb0231408be24920604395de"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a05d73b933a847d6cccdda8f838a22ff101ad9bf93e33684f39c1f5f0eece3d"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "web-sys"
+version = "0.3.77"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33b6dd2ef9186f1f2072e409e99cd22a975331a6b3591b12c764e0e55c60d5d2"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "winapi-util"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
+dependencies = [
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"

battlesnake/Cargo.toml

@@ -29,3 +29,10 @@ env_logger = "0.11"
 bitvec = "1.0"
 enum-iterator = "2.1"
 rand = "0.8"
+
+[dev-dependencies]
+criterion = "0.5"
+
+[[bench]]
+name = "simulation"
+harness = false

battlesnake/benches/simulation.rs

@@ -0,0 +1,220 @@
+use std::sync::atomic::{AtomicU32, Ordering};
+
+use criterion::{black_box, criterion_group, criterion_main, Bencher, BenchmarkId, Criterion};
+
+use battlesnake::types::{
+    simulation::Board,
+    wire::{Battlesnake, Board as WireBoard, Game, Request, RoyaleSettings, Ruleset, Settings},
+    Coord,
+};
+
+fn create_start_snake(coord: Coord) -> Battlesnake {
+    let id = format!("{coord:?}");
+    Battlesnake {
+        id: id.clone(),
+        name: id.clone(),
+        health: 100,
+        body: vec![coord; 3],
+        latency: "0".into(),
+        head: coord,
+        length: 3,
+        shout: String::new(),
+        squad: id,
+    }
+}
+
+fn create_standard_start_request(starts: [Coord; 4]) -> Request {
+    Request {
+        game: Game {
+            id: "test".into(),
+            ruleset: Ruleset {
+                name: "standard".into(),
+                version: "0".into(),
+                settings: Settings {
+                    food_spawn_chance: 15,
+                    minimum_food: 1,
+                    hazard_damage_per_turn: 30,
+                    royale: RoyaleSettings {
+                        shrink_every_n_turns: 20,
+                    },
+                },
+            },
+            map: "standard".into(),
+            timeout: 500,
+            source: "other".into(),
+        },
+        turn: 0,
+        board: WireBoard {
+            height: 11,
+            width: 11,
+            food: vec![Coord { x: 5, y: 5 }],
+            hazards: vec![],
+            snakes: vec![
+                create_start_snake(starts[0]),
+                create_start_snake(starts[1]),
+                create_start_snake(starts[2]),
+                create_start_snake(starts[3]),
+            ],
+        },
+        you: create_start_snake(starts[0]),
+    }
+}
+
+fn standard(c: &mut Criterion) {
+    let turns_min = AtomicU32::new(u32::MAX);
+    let turns_max = AtomicU32::new(u32::MIN);
+    let turns_sum = AtomicU32::new(0);
+    let turns_total = AtomicU32::new(0);
+    let mut group = c.benchmark_group("standard");
+    group.sample_size(10000);
+
+    let benchmark = |b: &mut Bencher, board: &Board| {
+        b.iter(|| {
+            let mut board = board.clone();
+            let turn = board.simulate_random(|board| {
+                if board.num_snakes() <= 1 {
+                    Some(board.turn())
+                } else {
+                    None
+                }
+            });
+
+            if turn < turns_min.load(Ordering::Relaxed) {
+                turns_min.store(turn, Ordering::Relaxed);
+            }
+            if turn > turns_max.load(Ordering::Relaxed) {
+                turns_max.store(turn, Ordering::Relaxed);
+            }
+            turns_sum.fetch_add(turn, Ordering::Relaxed);
+            turns_total.fetch_add(1, Ordering::Relaxed);
+        });
+    };
+
+    let request = create_standard_start_request([
+        Coord { x: 1, y: 1 },
+        Coord { x: 9, y: 1 },
+        Coord { x: 1, y: 9 },
+        Coord { x: 9, y: 9 },
+    ]);
+    let board = Board::from(&request);
+    group.bench_with_input(
+        BenchmarkId::from_parameter("start x"),
+        black_box(&board),
+        benchmark,
+    );
+    {
+        let max = turns_max.load(Ordering::Relaxed);
+        let min = turns_min.load(Ordering::Relaxed);
+        let sum = turns_sum.load(Ordering::Relaxed);
+        let total = turns_total.load(Ordering::Relaxed);
+        let avg = sum / total;
+        println!("turns: [{min}, {max}] avg {avg} @ {total} samples");
+        turns_max.store(u32::MIN, Ordering::Relaxed);
+        turns_min.store(u32::MAX, Ordering::Relaxed);
+        turns_sum.store(0, Ordering::Relaxed);
+        turns_total.store(0, Ordering::Relaxed);
+    }
+
+    let request = create_standard_start_request([
+        Coord { x: 5, y: 1 },
+        Coord { x: 1, y: 5 },
+        Coord { x: 5, y: 9 },
+        Coord { x: 9, y: 5 },
+    ]);
+    let board = Board::from(&request);
+    group.bench_with_input(
+        BenchmarkId::from_parameter("start +"),
+        black_box(&board),
+        benchmark,
+    );
+    {
+        let max = turns_max.load(Ordering::Relaxed);
+        let min = turns_min.load(Ordering::Relaxed);
+        let sum = turns_sum.load(Ordering::Relaxed);
+        let total = turns_total.load(Ordering::Relaxed);
+        let avg = sum / total;
+        println!("turns: [{min}, {max}] avg {avg} @ {total} samples");
+    }
+}
+
+fn constrictor(c: &mut Criterion) {
+    let turns_min = AtomicU32::new(u32::MAX);
+    let turns_max = AtomicU32::new(u32::MIN);
+    let turns_sum = AtomicU32::new(0);
+    let turns_total = AtomicU32::new(0);
+    let mut group = c.benchmark_group("constrictor");
+    group.sample_size(10000);
+
+    let benchmark = |b: &mut Bencher, board: &Board| {
+        b.iter(|| {
+            let mut board = board.clone();
+            let turn = board.simulate_random(|board| {
+                if board.num_snakes() <= 1 {
+                    Some(board.turn())
+                } else {
+                    None
+                }
+            });
+
+            if turn < turns_min.load(Ordering::Relaxed) {
+                turns_min.store(turn, Ordering::Relaxed);
+            }
+            if turn > turns_max.load(Ordering::Relaxed) {
+                turns_max.store(turn, Ordering::Relaxed);
+            }
+            turns_sum.fetch_add(turn, Ordering::Relaxed);
+            turns_total.fetch_add(1, Ordering::Relaxed);
+        });
+    };
+
+    let mut request = create_standard_start_request([
+        Coord { x: 1, y: 1 },
+        Coord { x: 9, y: 1 },
+        Coord { x: 1, y: 9 },
+        Coord { x: 9, y: 9 },
+    ]);
+    request.game.ruleset.name = "constrictor".into();
+    let board = Board::from(&request);
+    group.bench_with_input(
+        BenchmarkId::from_parameter("start x"),
+        black_box(&board),
+        benchmark,
+    );
+    {
+        let max = turns_max.load(Ordering::Relaxed);
+        let min = turns_min.load(Ordering::Relaxed);
+        let sum = turns_sum.load(Ordering::Relaxed);
+        let total = turns_total.load(Ordering::Relaxed);
+        let avg = sum / total;
+        println!("turns: [{min}, {max}] avg {avg} @ {total} samples");
+        turns_max.store(u32::MIN, Ordering::Relaxed);
+        turns_min.store(u32::MAX, Ordering::Relaxed);
+        turns_sum.store(0, Ordering::Relaxed);
+        turns_total.store(0, Ordering::Relaxed);
+    }
+
+    let mut request = create_standard_start_request([
+        Coord { x: 5, y: 1 },
+        Coord { x: 1, y: 5 },
+        Coord { x: 5, y: 9 },
+        Coord { x: 9, y: 5 },
+    ]);
+    request.game.ruleset.name = "constrictor".into();
+    let board = Board::from(&request);
+    group.bench_with_input(
+        BenchmarkId::from_parameter("start +"),
+        black_box(&board),
+        benchmark,
+    );
+    {
+        let max = turns_max.load(Ordering::Relaxed);
+        let min = turns_min.load(Ordering::Relaxed);
+        let sum = turns_sum.load(Ordering::Relaxed);
+        let total = turns_total.load(Ordering::Relaxed);
+        let avg = sum / total;
+        println!("turns: [{min}, {max}] avg {avg} @ {total} samples");
+    }
+}
+
+criterion_group!(benches, standard, constrictor);
+criterion_main!(benches);

battlesnake/src/lib.rs

@@ -0,0 +1 @@
+pub mod types;

battlesnake/src/main.rs

@@ -1,20 +1,18 @@
-mod types;
-
 use axum::{
     extract::Json,
     response,
     routing::{get, post},
     Router,
 };
-use log::{debug, info, warn};
+use battlesnake::types::{
-use rand::prelude::*;
-use serde::Serialize;
-use tokio::{net::TcpListener, time::Instant};
-use types::{
     simulation::Board,
     wire::{Request, Response},
     Direction,
 };
+use log::{debug, info, warn};
+use rand::prelude::*;
+use serde::Serialize;
+use tokio::{net::TcpListener, time::Instant};
 
 #[tokio::main]
 async fn main() {

battlesnake/src/types/mod.rs

@@ -6,11 +6,12 @@ pub mod wire;
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Deserialize)]
 pub struct Coord {
-    x: u8,
+    pub x: u8,
-    y: u8,
+    pub y: u8,
 }
 
 impl Coord {
+    #[must_use]
     pub fn apply(self, direction: Direction) -> Option<Self> {
         match direction {
             Direction::Up => self.y.checked_add(1).map(|y| Self { y, x: self.x }),
@@ -20,7 +21,8 @@ impl Coord {
         }
     }
 
-    pub fn wrapping_apply(mut self, direction: Direction) -> Self {
+    #[must_use]
+    pub const fn wrapping_apply(mut self, direction: Direction) -> Self {
         match direction {
             Direction::Up => self.y = self.y.wrapping_add(1),
             Direction::Down => self.y = self.y.wrapping_sub(1),

battlesnake/src/types/simulation.rs

@@ -121,20 +121,29 @@ impl Display for Board {
 }
 
 impl Board {
+    #[must_use]
+    pub const fn turn(&self) -> u32 {
+        self.turn
+    }
+
+    #[must_use]
     pub fn num_snakes(&self) -> usize {
         self.snakes.len()
     }
 
+    #[must_use]
     pub fn is_food(&self, tile: Coord) -> bool {
         let index = self.coord_to_linear(tile);
         self.food[index]
     }
 
+    #[must_use]
     pub fn is_hazard(&self, tile: Coord) -> bool {
         let index = self.coord_to_linear(tile);
         self.hazard[index]
     }
 
+    #[must_use]
     pub fn is_free(&self, tile: Coord) -> bool {
         if !(tile.x < self.width && tile.y < self.height) {
             return false;
@@ -182,6 +191,7 @@ impl Board {
         self.eliminate_snake_standard();
         self.update_free_map();
         self.spawn_food();
+        self.turn += 1;
     }
 
     fn move_standard(&mut self, actions: &[(u8, Direction)]) {
@@ -232,6 +242,13 @@ impl Board {
     }
 
     fn feed_snakes_standard(&mut self) {
+        if self.constrictor {
+            for snake in &mut self.snakes {
+                snake.health = 100;
+                let tail = snake.tail();
+                snake.body.push_back(tail);
+            }
+        } else {
             let mut eaten_food = vec![];
             for i in 0..self.snakes.len() {
                 let head = self.snakes[i].head();
@@ -250,6 +267,7 @@ impl Board {
                 self.food.set(food_index, false);
             }
         }
+    }
 
     fn eliminate_snake_standard(&mut self) {
         // eliminate out of health and out of bounds