From 65ccc41aa1a4b8cf54fd3e34f094eb791af79134 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Tue, 21 Apr 2026 18:36:41 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20Optimize=20Tarjan's=20DFS?=
 =?UTF-8?q?=20in=20invalidation=20detector=20by=20eliminating=20redundant?=
 =?UTF-8?q?=20PathBuf=20allocations?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

By switching to owned PathBuf instances purely for insertion, and utilizing &Path for all subsequent read/write `HashMap` interactions, we prevent repeated heap allocations taking place during every node evaluation within O(V+E) traversal.

Co-authored-by: bashandbone <89049923+bashandbone@users.noreply.github.com>
---
 crates/flow/src/incremental/invalidation.rs | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/crates/flow/src/incremental/invalidation.rs b/crates/flow/src/incremental/invalidation.rs
index da9ac9c..b2e1e92 100644
--- a/crates/flow/src/incremental/invalidation.rs
+++ b/crates/flow/src/incremental/invalidation.rs
@@ -342,11 +342,13 @@ impl InvalidationDetector {
     fn tarjan_dfs(&self, v: &Path, state: &mut TarjanState, sccs: &mut Vec<Vec<PathBuf>>) {
         // Initialize node
         let index = state.index_counter;
-        state.indices.insert(v.to_path_buf(), index);
-        state.lowlinks.insert(v.to_path_buf(), index);
+
+        let v_owned = v.to_path_buf();
+        state.indices.insert(v_owned.clone(), index);
+        state.lowlinks.insert(v_owned.clone(), index);
         state.index_counter += 1;
-        state.stack.push(v.to_path_buf());
-        state.on_stack.insert(v.to_path_buf());
+        state.stack.push(v_owned.clone());
+        state.on_stack.insert(v_owned);
 
         // Visit all successors (dependencies)
         let dependencies = self.graph.get_dependencies(v);
@@ -358,19 +360,19 @@ impl InvalidationDetector {
 
                 // Update lowlink
                 let w_lowlink = *state.lowlinks.get(dep).unwrap();
-                let v_lowlink = state.lowlinks.get_mut(&v.to_path_buf()).unwrap();
+                let v_lowlink = state.lowlinks.get_mut(v).unwrap();
                 *v_lowlink = (*v_lowlink).min(w_lowlink);
             } else if state.on_stack.contains(dep) {
                 // Successor is on stack (part of current SCC)
                 let w_index = *state.indices.get(dep).unwrap();
-                let v_lowlink = state.lowlinks.get_mut(&v.to_path_buf()).unwrap();
+                let v_lowlink = state.lowlinks.get_mut(v).unwrap();
                 *v_lowlink = (*v_lowlink).min(w_index);
             }
         }
 
         // If v is a root node, pop the stack to create an SCC
-        let v_index = *state.indices.get(&v.to_path_buf()).unwrap();
-        let v_lowlink = *state.lowlinks.get(&v.to_path_buf()).unwrap();
+        let v_index = *state.indices.get(v).unwrap();
+        let v_lowlink = *state.lowlinks.get(v).unwrap();
 
         if v_lowlink == v_index {
             let mut scc = Vec::new();