issue-936: fix race during app termination because of signal (#950)

* issue-936: fix race during app termination because of signal

* add eol

cloud/storage/core/libs/daemon/app.cpp

@@ -58,10 +58,11 @@ class TMainThread
         return ShouldContinue->GetReturnCode();
     }
 
-    void Stop(int exitCode)
+    void Stop()
     {
-        if (AtomicCas(&State, Stopped, Started)) {
-            ShouldContinue->ShouldStop(exitCode);
+        auto prevState = AtomicSwap(&State, Stopped);
+        if (prevState == Started) {
+            ShouldContinue->ShouldStop(0);
             WaitCondVar.Signal();
         }
     }
@@ -72,7 +73,7 @@ class TMainThread
 void ProcessSignal(int signum)
 {
     if (signum == SIGINT || signum == SIGTERM) {
-        AppStop(0);
+        AppStop();
     }
 }
 
@@ -97,9 +98,9 @@ int AppMain(TProgramShouldContinue& shouldContinue)
     return TMainThread::GetInstance()->Run(shouldContinue);
 }
 
-void AppStop(int exitCode)
+void AppStop()
 {
-    TMainThread::GetInstance()->Stop(exitCode);
+    TMainThread::GetInstance()->Stop();
 }
 
 ////////////////////////////////////////////////////////////////////////////////

cloud/storage/core/libs/daemon/app.h

@@ -10,7 +10,7 @@ namespace NCloud {
 
 void AppCreate();
 int AppMain(TProgramShouldContinue& shouldContinue);
-void AppStop(int exitCode);
+void AppStop();
 
 void ConfigureSignals();
 

cloud/storage/core/libs/daemon/app_ut.cpp

@@ -0,0 +1,23 @@
+#include "app.h"
+
+#include <contrib/ydb/library/actors/util/should_continue.h>
+
+#include <library/cpp/testing/unittest/registar.h>
+
+
+namespace NCloud {
+
+////////////////////////////////////////////////////////////////////////////////
+
+Y_UNIT_TEST_SUITE(TAppMainThreadTest)
+{
+    Y_UNIT_TEST(ShouldHandleStopBeforeAppMain)
+    {
+        TProgramShouldContinue shouldContinue;
+        AppCreate();
+        AppStop();
+        AppMain(shouldContinue);
+    }
+}
+
+}   // namespace NCloud

cloud/storage/core/libs/daemon/ut/ya.make

@@ -0,0 +1,7 @@
+UNITTEST_FOR(cloud/storage/core/libs/daemon)
+
+SRCS(
+    app_ut.cpp
+)
+
+END()

cloud/storage/core/libs/daemon/ya.make

@@ -18,3 +18,5 @@ PEERDIR(
 )
 
 END()
+
+RECURSE_FOR_TESTS(ut)