From 8d257f5510dbfbab8a74e2b7b0ff60bcd720e141 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Thu, 3 Jul 2025 13:21:30 +0200
Subject: [PATCH] EvalState: Make the counters atomic

---
 src/libexpr/eval.cc                  | 30 ++++++++++++++--------------
 src/libexpr/include/nix/expr/eval.hh | 26 ++++++++++++------------
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 87b1e73a5..a953e20d7 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -892,7 +892,7 @@ Value * EvalState::getBool(bool b)
     return b ? &Value::vTrue : &Value::vFalse;
 }
 
-unsigned long nrThunks = 0;
+static std::atomic<uint64_t> nrThunks = 0;
 
 static inline void mkThunk(Value & v, Env & env, Expr * expr)
 {
@@ -2940,18 +2940,18 @@ void EvalState::printStatistics()
 #endif
     };
     topObj["envs"] = {
-        {"number", nrEnvs},
-        {"elements", nrValuesInEnvs},
+        {"number", nrEnvs.load()},
+        {"elements", nrValuesInEnvs.load()},
         {"bytes", bEnvs},
     };
     topObj["nrExprs"] = Expr::nrExprs;
     topObj["list"] = {
-        {"elements", nrListElems},
+        {"elements", nrListElems.load()},
         {"bytes", bLists},
-        {"concats", nrListConcats},
+        {"concats", nrListConcats.load()},
     };
     topObj["values"] = {
-        {"number", nrValues},
+        {"number", nrValues.load()},
         {"bytes", bValues},
     };
     topObj["symbols"] = {
@@ -2959,9 +2959,9 @@ void EvalState::printStatistics()
         {"bytes", symbols.totalSize()},
     };
     topObj["sets"] = {
-        {"number", nrAttrsets},
+        {"number", nrAttrsets.load()},
         {"bytes", bAttrsets},
-        {"elements", nrAttrsInAttrsets},
+        {"elements", nrAttrsInAttrsets.load()},
     };
     topObj["sizes"] = {
         {"Env", sizeof(Env)},
@@ -2969,13 +2969,13 @@ void EvalState::printStatistics()
         {"Bindings", sizeof(Bindings)},
         {"Attr", sizeof(Attr)},
     };
-    topObj["nrOpUpdates"] = nrOpUpdates;
-    topObj["nrOpUpdateValuesCopied"] = nrOpUpdateValuesCopied;
-    topObj["nrThunks"] = nrThunks;
-    topObj["nrAvoided"] = nrAvoided;
-    topObj["nrLookups"] = nrLookups;
-    topObj["nrPrimOpCalls"] = nrPrimOpCalls;
-    topObj["nrFunctionCalls"] = nrFunctionCalls;
+    topObj["nrOpUpdates"] = nrOpUpdates.load();
+    topObj["nrOpUpdateValuesCopied"] = nrOpUpdateValuesCopied.load();
+    topObj["nrThunks"] = nrThunks.load();
+    topObj["nrAvoided"] = nrAvoided.load();
+    topObj["nrLookups"] = nrLookups.load();
+    topObj["nrPrimOpCalls"] = nrPrimOpCalls.load();
+    topObj["nrFunctionCalls"] = nrFunctionCalls.load();
 #if NIX_USE_BOEHMGC
     topObj["gc"] = {
         {"heapSize", heapSize},
diff --git a/src/libexpr/include/nix/expr/eval.hh b/src/libexpr/include/nix/expr/eval.hh
index 8f7a0ec32..958b6fbee 100644
--- a/src/libexpr/include/nix/expr/eval.hh
+++ b/src/libexpr/include/nix/expr/eval.hh
@@ -961,19 +961,19 @@ private:
      */
     std::string mkSingleDerivedPathStringRaw(const SingleDerivedPath & p);
 
-    unsigned long nrEnvs = 0;
-    unsigned long nrValuesInEnvs = 0;
-    unsigned long nrValues = 0;
-    unsigned long nrListElems = 0;
-    unsigned long nrLookups = 0;
-    unsigned long nrAttrsets = 0;
-    unsigned long nrAttrsInAttrsets = 0;
-    unsigned long nrAvoided = 0;
-    unsigned long nrOpUpdates = 0;
-    unsigned long nrOpUpdateValuesCopied = 0;
-    unsigned long nrListConcats = 0;
-    unsigned long nrPrimOpCalls = 0;
-    unsigned long nrFunctionCalls = 0;
+    std::atomic<uint64_t> nrEnvs = 0;
+    std::atomic<uint64_t> nrValuesInEnvs = 0;
+    std::atomic<uint64_t> nrValues = 0;
+    std::atomic<uint64_t> nrListElems = 0;
+    std::atomic<uint64_t> nrLookups = 0;
+    std::atomic<uint64_t> nrAttrsets = 0;
+    std::atomic<uint64_t> nrAttrsInAttrsets = 0;
+    std::atomic<uint64_t> nrAvoided = 0;
+    std::atomic<uint64_t> nrOpUpdates = 0;
+    std::atomic<uint64_t> nrOpUpdateValuesCopied = 0;
+    std::atomic<uint64_t> nrListConcats = 0;
+    std::atomic<uint64_t> nrPrimOpCalls = 0;
+    std::atomic<uint64_t> nrFunctionCalls = 0;
 
     bool countCalls;