From 46f65058655550bff87cf547954f7ca5622d1b2d Mon Sep 17 00:00:00 2001
From: Jeremy Kolb <kjeremy@gmail.com>
Date: Wed, 4 Sep 2024 10:14:51 -0400
Subject: [PATCH] Pull fut.get() out of the lock

This is https://gerrit.lix.systems/c/lix/+/1462 by @jade_

see: https://git.lix.systems/lix-project/lix/issues/366
see: https://gerrit.lix.systems/c/lix/+/1462
---
 src/libstore/store-api.cc | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 8eef340cc..fc03133f8 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -822,14 +822,25 @@ StorePathSet Store::queryValidPaths(const StorePathSet & paths, SubstituteFlag m
     auto doQuery = [&](const StorePath & path) {
         checkInterrupt();
         queryPathInfo(path, {[path, &state_, &wakeup](std::future<ref<const ValidPathInfo>> fut) {
-            auto state(state_.lock());
+            bool exists = false;
+            std::exception_ptr newExc{};
+
             try {
                 auto info = fut.get();
-                state->valid.insert(path);
+                exists = true;
             } catch (InvalidPath &) {
             } catch (...) {
-                state->exc = std::current_exception();
+                newExc = std::current_exception();
             }
+
+            auto state(state_.lock());
+
+            if (exists)
+                state->valid.insert(path);
+
+            if (newExc != nullptr)
+                state->exc = newExc;
+
             assert(state->left);
             if (!--state->left)
                 wakeup.notify_one();