From f0156ccec40646b10ac19bf98098f162705bec02 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Max=20K=C3=A4nner?= <max.kaenner@gmail.com>
Date: Tue, 24 Jun 2025 20:59:32 +0200
Subject: [PATCH] add multithreading for seed cracking

---
 Cargo.lock                          |  1 +
 battlesnake/Cargo.toml              |  1 +
 battlesnake/src/bin/seed-cracker.rs | 60 +++++++++++++++++++++++------
 3 files changed, 51 insertions(+), 11 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 1e7e7c6..135bce6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -224,6 +224,7 @@ dependencies = [
  "lru",
  "memmap2",
  "rand 0.9.1",
+ "rayon",
  "serde",
  "serde_json",
  "sqlx",
diff --git a/battlesnake/Cargo.toml b/battlesnake/Cargo.toml
index fc00ac4..5aa0af1 100644
--- a/battlesnake/Cargo.toml
+++ b/battlesnake/Cargo.toml
@@ -55,6 +55,7 @@ memmap2 = "0.9.5"
 bytemuck = "1.23.1"
 flame = "0.2.2"
 flamer = "0.5.0"
+rayon = "1.10.0"
 
 [dev-dependencies]
 criterion = "0.5"
diff --git a/battlesnake/src/bin/seed-cracker.rs b/battlesnake/src/bin/seed-cracker.rs
index e008e3b..9bfee59 100644
--- a/battlesnake/src/bin/seed-cracker.rs
+++ b/battlesnake/src/bin/seed-cracker.rs
@@ -1,4 +1,13 @@
-use std::{fs::File, path::PathBuf, sync::LazyLock, time::Instant};
+use std::{
+    cell::RefCell,
+    fs::File,
+    path::PathBuf,
+    sync::{
+        LazyLock,
+        atomic::{AtomicU32, Ordering},
+    },
+    time::Instant,
+};
 
 use az::{Az, WrappingAs};
 use battlesnake::types::{Coord, Direction, wire::Request};
@@ -8,6 +17,7 @@ use clap::Parser;
 use hashbrown::HashMap;
 use log::{debug, error, info, trace};
 use memmap2::{Mmap, MmapOptions};
+use rayon::iter::{IntoParallelIterator, ParallelIterator};
 
 type DynError = Box<dyn std::error::Error>;
 
@@ -21,6 +31,9 @@ struct Args {
     #[arg()]
     /// The file to read the requests from
     file: PathBuf,
+    /// Use multiple cores to speed up search
+    #[arg(long, short)]
+    parallel: bool,
 }
 
 //#[flame]
@@ -65,18 +78,43 @@ fn main() -> Result<(), DynError> {
     } else {
         info!("Trying every seed from 1 to {}", i32::MAX);
         let start = Instant::now();
-        for seed in 1..i32::MAX {
-            if seed % 1_000_000 == 0 {
-                debug!("Checking {seed:>10}");
+        if args.parallel {
+            thread_local! {
+                static RAND: RefCell<SeedRand> = RefCell::new(SeedRand::new(0));
             }
-            if prepared.validate(&mut rand, i64::from(seed), false) {
-                let elapsed = start.elapsed();
-                info!(
-                    "Trying {seed} seeds took {elapsed:?} ({:?} / seed)",
-                    elapsed / seed.az()
-                );
+            let tried = AtomicU32::new(0);
+            let seed = (1..i32::MAX).into_par_iter().find_any(|seed| {
+                tried.fetch_add(1, Ordering::Relaxed);
+                RAND.with_borrow_mut(|rand| prepared.validate(rand, i64::from(*seed), false))
+            });
+            let elapsed = start.elapsed();
+            let tried = tried.load(Ordering::Relaxed);
+            info!(
+                "Trying {tried} seeds took {elapsed:?} ({:?} / seed)",
+                elapsed / tried.az()
+            );
+            if let Some(seed) = seed {
                 println!("The correct seed is {seed}");
-                break;
+            } else {
+                println!("No valid seed found");
+            }
+        } else {
+            let seed = (1..i32::MAX).find(|seed| {
+                if seed % 1_000_000 == 0 {
+                    debug!("Checking {seed:>10}");
+                }
+                prepared.validate(&mut rand, i64::from(*seed), false)
+            });
+            let elapsed = start.elapsed();
+            let tried = seed.unwrap_or(i32::MAX);
+            info!(
+                "Trying {tried} seeds took {elapsed:?} ({:?} / seed)",
+                elapsed / tried.az()
+            );
+            if let Some(seed) = seed {
+                println!("The correct seed is {seed}");
+            } else {
+                println!("No valid seed found");
             }
         }
     }