add instrumenting support to Bot, returns basic info about algorithm

fish/src/bot.rs

@@ -2,10 +2,10 @@
 //! anytime algorithm that will provide a suggestion for the next move. It may be
 //! repeatedly polled by the `think` method in order to attempt to improve the suggestion.
 
-use core::ops::Range;
+use alloc::boxed::Box;
-
 use alloc::collections::BinaryHeap;
 use alloc::vec::Vec;
+use core::ops::Range;
 use mino::matrix::Mat;
 use mino::srs::{Piece, Queue};
 
@@ -14,18 +14,32 @@ mod trans;
 
 use crate::bot::node::{Node, RawNodePtr};
 use crate::bot::trans::TransTable;
-use crate::eval::{features, Weights};
+use crate::eval::{features, Features, Weights};
 
 pub(crate) use bumpalo::Bump as Arena;
 
 /// Encompasses an instance of the algorithm.
 pub struct Bot {
-    iters: u32,
     evaluator: Evaluator,
     trans: TransTable,
     algorithm: SegmentedAStar,
     // IMPORTANT: `arena` must occur after `algorithm` so that it is dropped last.
     arena: Arena,
+    iters: u32,
+    metrics: Option<Box<Metrics>>,
+}
+
+#[derive(Clone, Eq, PartialEq, Debug)]
+pub struct Metrics {
+    pub start_features: Features,
+    pub start_heuristic: i32,
+    pub end_features: Features,
+    pub end_heuristic: i32,
+    pub end_rating: (bool, i32),
+    pub end_iteration: u32,
+    // TODO(?) memory usage metrics
+    // TODO(?) transposition table metrics
+    // TODO(?) A* metrics
 }
 
 impl Bot {
@@ -37,11 +51,12 @@ impl Bot {
         let trans = TransTable::new();
         let algorithm = SegmentedAStar::new(root);
         Self {
-            iters: 0,
             evaluator,
             trans,
             algorithm,
             arena,
+            iters: 0,
+            metrics: None,
         }
     }
 
@@ -66,12 +81,19 @@ impl Bot {
                 &self.evaluator,
                 &mut self.iters,
             );
+
             if did_update {
                 tracing::debug!(
                     "new suggestion @ {}: {:?}",
                     self.iters,
-                    self.algorithm.best().unwrap(),
+                    self.algorithm.best(),
                 );
+
+                if let Some(metrics) = self.metrics.as_deref_mut() {
+                    let weights = &self.evaluator.weights;
+                    let start = self.algorithm.best();
+                    metrics.updated_best(weights, start, self.iters);
+                }
             }
         }
     }
@@ -86,7 +108,20 @@ impl Bot {
     /// - `think` has not been called enough times to provide an initial suggestion.
     /// - there are no valid placements for the initial state
     pub fn suggest(&self) -> Option<Piece> {
-        self.algorithm.best().and_then(|node| node.root_placement())
+        self.algorithm.best().root_placement()
+    }
+
+    /// Start collecting metrics about the search algorithm. Uses the current suggestion
+    /// as the "start" of the metrics data.
+    pub fn start_instrumenting(&mut self) {
+        let weights = &self.evaluator.weights;
+        let start = self.algorithm.best();
+        self.metrics = Some(Metrics::new(weights, start, self.iters).into());
+    }
+
+    /// Returns the current metrics, if enabled by `start_instrumenting`.
+    pub fn metrics(&self) -> Option<Metrics> {
+        self.metrics.as_deref().cloned()
     }
 }
 
@@ -127,6 +162,33 @@ impl Evaluator {
     }
 }
 
+impl Metrics {
+    fn new(weights: &Weights, start: &Node, iters: u32) -> Self {
+        let features = features(start.matrix(), 0);
+        let heuristic = features.evaluate(weights);
+        let rating = start.rating();
+        Self {
+            start_features: features,
+            start_heuristic: heuristic,
+            end_features: features,
+            end_heuristic: heuristic,
+            end_rating: rating,
+            end_iteration: iters,
+        }
+    }
+
+    #[cold]
+    fn updated_best(&mut self, weights: &Weights, node: &Node, iters: u32) {
+        let features = features(node.matrix(), 0);
+        let heuristic = features.evaluate(weights);
+        let rating = node.rating();
+        self.end_features = features;
+        self.end_heuristic = heuristic;
+        self.end_rating = rating;
+        self.end_iteration = iters;
+    }
+}
+
 // This implements an algorithm that is very similar to A* but has a slight
 // modification. Rather than one big open set, there are separate sets at each depth of
 // the search. After picking a node from one open set and expanding its children into the
@@ -154,7 +216,7 @@ impl Evaluator {
 struct SegmentedAStar {
     open: Vec<BinaryHeap<AStarNode>>,
     depth: usize,
-    best: Option<RawNodePtr>,
+    best: RawNodePtr,
 }
 
 impl SegmentedAStar {
@@ -165,12 +227,12 @@ impl SegmentedAStar {
         Self {
             open,
             depth: 0,
-            best: None,
+            best: root.into(),
         }
     }
 
-    fn best(&self) -> Option<&Node> {
+    fn best(&self) -> &Node {
-        self.best.map(|node| unsafe { node.as_node() })
+        unsafe { self.best.as_node() }
     }
 
     fn step(
@@ -229,9 +291,10 @@ impl SegmentedAStar {
         Ok(work)
     }
 
+    #[cold]
     fn backup(&mut self, cand: &Node) -> bool {
-        if self.best().map_or(true, |best| cand.is_better(best)) {
+        if cand.is_better(self.best()) {
-            self.best = Some(cand.into());
+            self.best = cand.into();
             true
         } else {
             false

fish/src/bot/node.rs

@@ -70,10 +70,16 @@ impl Node {
         unsafe { self.queue.as_queue() }
     }
 
+    pub fn rating(&self) -> (bool, i32) {
+        self.rating
+    }
+
+    // TODO: move this function to `bot.algorithm`
     pub fn is_better(&self, other: &Node) -> bool {
         self.rating > other.rating
     }
 
+    // TODO: move this function to `bot.algorithm`
     pub fn is_terminal(&self) -> bool {
         self.queue().is_empty() || self.rating.0
     }
@@ -146,7 +152,7 @@ impl core::fmt::Debug for Node {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         write!(f, "Node {{ ")?;
         match self.rating {
-            (false, h) => write!(f, "heuristic: {}", h),
+            (false, h) => write!(f, "rating: {}", h),
             (true, n) => write!(f, "solution: {}", -n),
         }?;
         if let Some(pc) = self.root_placement() {