feat util/system: add a possibility to disable exit handlers, use it in rate-limiter nginx module

b90ea2b46b910c5bf2e0db4ccacb45ca5c39ecaa

2 files changed, 21 insertions, 0 deletions

diff --git a/util/system/atexit.cpp b/util/system/atexit.cpp
index 7fafad95a6..09fa7d8381 100644
--- a/util/system/atexit.cpp
+++ b/util/system/atexit.cpp
@@ -36,6 +36,9 @@ namespace {
 
         inline void Finish() noexcept {
             FinishStarted_.store(true);
+            if (ExitHandlersDisabled_.load()) {
+                return;
+            }
 
             auto guard = Guard(Lock_);
 
@@ -69,11 +72,16 @@ namespace {
             return FinishStarted_.load();
         }
 
+        inline void DisableExitHandlers() {
+            ExitHandlersDisabled_.store(true);
+        }
+
     private:
         TAdaptiveLock Lock_;
         std::atomic<bool> FinishStarted_;
         TDeque<TFunc> Store_;
         TPriorityQueue<TFunc*, TVector<TFunc*>, TCmp> Items_;
+        std::atomic<bool> ExitHandlersDisabled_{false};
     };
 
     static TAdaptiveLock atExitLock;
@@ -134,3 +142,7 @@ void AtExit(TTraditionalAtExitFunc func) {
 void AtExit(TTraditionalAtExitFunc func, size_t priority) {
     AtExit(TraditionalCloser, reinterpret_cast<void*>(func), priority);
 }
+
+void DisableExitHandlers() {
+    Instance()->DisableExitHandlers();
+}
diff --git a/util/system/atexit.h b/util/system/atexit.h
index eb3188615c..72096ec9e2 100644
--- a/util/system/atexit.h
+++ b/util/system/atexit.h
@@ -20,3 +20,12 @@ bool ExitStarted();
  * Calls in the moment when application is not terminating - bad idea.
  */
 void ManualRunAtExitFinalizers();
+
+/**
+ * You shouldn't ever need this, unless you are writing some DLL modules,
+ * which might get unloaded before application termination (nginx's modules, for example).
+ * If a DLL sets exit handlers which belong to the DLL itself, these handlers point to
+ * nowhere after the DLL has been unloaded, and an attempt to invoke any of those at the
+ * application termination leads to a crash.
+ */
+void DisableExitHandlers();