Add depth based time limit

src/search/iterative_deepening.rs

@@ -17,7 +17,7 @@ pub fn iterative_deepening(
     let mut best_move = None;
 
     for depth in 1..=max_depth {
-        if time.exceed_hard_limit() {
+        if time.exceed_soft_limit() {
             return Ok(best_move);
         }
 

src/search/mod.rs

@@ -9,6 +9,6 @@ pub mod transposition_table;
 pub const MAX_DEPTH: u8 = 50;
 pub const TIME: u128 = 1000;
 pub const INC: u128 = 1000;
-pub const HARD_LIMIT_DIVISION: u128 = 10;
+pub const HARD_LIMIT_DIVISION: u128 = 3;
-pub const SOFT_LIMIT_DIVISION: u128 = HARD_LIMIT_DIVISION * 2;
+pub const SOFT_LIMIT_DIVISION: u128 = 20;
-pub const MAX_TT_SIZE: u64 = 750000;
+pub const MAX_TT_SIZE: u64 = 3000000;

src/search/quiescence.rs

@@ -9,9 +9,9 @@ pub fn quiescence(
     mut alpha: i32,
     beta: i32,
     time: &TimeInfo,
-    total_nodes_searched: &mut u64,
+    nodes: &mut u64,
 ) -> Result<i32> {
-    if time.exceed_hard_limit() {
+    if *nodes & 1024 == 0 && time.exceed_hard_limit() {
         bail!("Hard limit exceeded in quiescence");
     }
 
@@ -52,7 +52,7 @@ pub fn quiescence(
             game.unmake_move();
             continue;
         }
-        *total_nodes_searched += 1;
+        *nodes += 1;
 
         let score = -quiescence(game, -beta, -alpha, time, &mut 0)?;
         game.unmake_move();

src/search/time.rs

@@ -1,6 +1,6 @@
 use std::time::Instant;
 
-use super::HARD_LIMIT_DIVISION;
+use super::{HARD_LIMIT_DIVISION, SOFT_LIMIT_DIVISION};
 
 pub struct TimeInfo {
     pub instant: Instant,
@@ -20,4 +20,8 @@ impl TimeInfo {
     pub fn exceed_hard_limit(&self) -> bool {
         self.instant.elapsed().as_millis() >= self.time / HARD_LIMIT_DIVISION + self.inc / 2
     }
+
+    pub fn exceed_soft_limit(&self) -> bool {
+        self.instant.elapsed().as_millis() >= self.time / SOFT_LIMIT_DIVISION + self.inc / 2
+    }
 }