issue-4548: fix filestore-server crashing while processing a nullptr event in TIndexTabletActor::StateZombie

cloud/storage/core/libs/throttling/tablet_throttler.cpp

@@ -62,6 +62,10 @@ class TTabletThrottler final
 
     void OnShutDown(const NActors::TActorContext&) override
     {
+        if (PostponedQueueFlushInProgress) {
+            // We are already in the process of flushing postponed requests
+            return;
+        }
         PostponedQueueFlushScheduled = false;
 
         while (PostponedRequests.size()) {
@@ -71,6 +75,8 @@ class TTabletThrottler final
             TAutoPtr<NActors::IEventHandle> ev = x.Event.release();
             Owner.Receive(ev);
 
+            // When shutting down, we do not expect that the actor will try to
+            // schedule flushing again
             Y_ABORT_UNLESS(!PostponedQueueFlushScheduled);
             PostponedRequests.pop_front();
         }

cloud/storage/core/libs/throttling/tablet_throttler_ut.cpp

@@ -0,0 +1,200 @@
+#include "tablet_throttler.h"
+
+#include "tablet_throttler_logger.h"
+#include "tablet_throttler_policy.h"
+
+#include <cloud/storage/core/libs/actors/helpers.h>
+#include <cloud/storage/core/libs/common/context.h>
+
+#include <contrib/ydb/core/testlib/basics/runtime.h>
+#include <contrib/ydb/library/actors/core/actor.h>
+#include <contrib/ydb/library/actors/core/hfunc.h>
+
+#include <library/cpp/testing/unittest/registar.h>
+
+namespace NCloud {
+
+////////////////////////////////////////////////////////////////////////////////
+
+namespace {
+
+////////////////////////////////////////////////////////////////////////////////
+
+using namespace NActors;
+
+class TSampleActorWithThrottler final: public TActor<TSampleActorWithThrottler>
+{
+public:
+    TSampleActorWithThrottler()
+        : TActor(&TThis::StateWork)
+    {}
+
+    void ResetThrottler(ITabletThrottlerPtr throttler)
+    {
+        Throttler = std::move(throttler);
+    }
+
+    STRICT_STFUNC(
+        StateWork, HFunc(NActors::TEvents::TEvWakeup, HandleWakeUp);
+        HFunc(NActors::TEvents::TEvFlushLog, HandleFlush));
+
+    STRICT_STFUNC(
+        StateZombie, HFunc(NActors::TEvents::TEvWakeup, RejectRequest);)
+
+    void HandleWakeUp(
+        const NActors::TEvents::TEvWakeup::TPtr& ev,
+        const NActors::TActorContext& ctx)
+    {
+        if (RequestsCount++ == 0) {
+            // The first request should be postponed
+
+            auto callContext =
+                MakeIntrusive<TCallContextBase>(static_cast<ui64>(0));
+            auto requestInfo = TThrottlingRequestInfo{};
+
+            Throttler->Throttle(
+                ctx,
+                callContext,
+                requestInfo,
+                [ev]() -> NActors::IEventHandlePtr
+                { return NActors::IEventHandlePtr(ev.Release()); },
+                "TestMethod");
+        } else {
+            Become(&TThis::StateZombie);
+
+            Throttler->OnShutDown(ctx);
+        }
+    }
+
+    void HandleFlush(
+        const NActors::TEvents::TEvFlushLog::TPtr& ev,
+        const NActors::TActorContext& ctx)
+    {
+        Y_UNUSED(ev);
+        Throttler->StartFlushing(ctx);
+    }
+
+    static void RejectRequest(
+        const NActors::TEvents::TEvWakeup::TPtr& ev,
+        const NActors::TActorContext& ctx)
+    {
+        auto response = std::make_unique<NActors::TEvents::TEvActorDied>();
+        NCloud::Reply(ctx, *ev, std::move(response));
+    }
+
+private:
+    ITabletThrottlerPtr Throttler;
+
+    ui64 RequestsCount = 0;
+};
+
+/////////////////////////////////////////////////////////////////////////////
+
+struct TTabletThrottlerLoggerStub: public ITabletThrottlerLogger
+{
+    void LogRequestPostponedBeforeSchedule(
+        const NActors::TActorContext& ctx,
+        TCallContextBase& callContext,
+        TDuration delay,
+        const char* methodName) const override
+    {
+        Y_UNUSED(ctx, callContext, delay, methodName);
+    }
+
+    void LogRequestPostponedAfterSchedule(
+        const NActors::TActorContext& ctx,
+        TCallContextBase& callContext,
+        ui32 postponedCount,
+        const char* methodName) const override
+    {
+        Y_UNUSED(ctx, callContext, postponedCount, methodName);
+    }
+
+    void LogRequestAdvanced(
+        const NActors::TActorContext& ctx,
+        TCallContextBase& callContext,
+        const char* methodName,
+        ui32 opType,
+        TDuration delay) const override
+    {
+        Y_UNUSED(ctx, callContext, methodName, opType, delay);
+    }
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+struct TTabletThrottlerPolicyAlwaysPostpone: public ITabletThrottlerPolicy
+{
+    bool TryPostpone(
+        TInstant ts,
+        const TThrottlingRequestInfo& requestInfo) override
+    {
+        Y_UNUSED(ts, requestInfo);
+        return true;
+    }
+
+    TMaybe<TDuration> SuggestDelay(
+        TInstant ts,
+        TDuration queueTime,
+        const TThrottlingRequestInfo& requestInfo) override
+    {
+        Y_UNUSED(ts, queueTime, requestInfo);
+        return TDuration::Seconds(1);
+    }
+
+    void OnPostponedEvent(
+        TInstant ts,
+        const TThrottlingRequestInfo& requestInfo) override
+    {
+        Y_UNUSED(ts, requestInfo);
+    }
+};
+
+}   // namespace
+
+Y_UNIT_TEST_SUITE(TTabletThrottlerTest)
+{
+    /**
+     * Scenario that caused a crash:
+     * 1. A request is present in the postponed queue
+     * 2. Throttler flush is initiated
+     * 3. During the processing of the postponed queue, an actor shutdown is
+     *    initiated
+     * 4. During the shutdown, Throttle->OnShutDown is called. It is not
+     *    supposed to process the request that was initially in the postponed
+     *    queue the second time.
+     */
+    Y_UNIT_TEST(ShouldNotFlushNullEventOnShutdown)
+    {
+        TTabletThrottlerLoggerStub logger;
+        TTabletThrottlerPolicyAlwaysPostpone policy;
+
+        std::unique_ptr<TSampleActorWithThrottler> actor =
+            std::make_unique<TSampleActorWithThrottler>();
+        auto throttler = CreateTabletThrottler(*actor, logger, policy);
+        actor->ResetThrottler(std::move(throttler));
+
+        TTestActorRuntimeBase runtime;
+        runtime.Initialize();
+
+        auto senderId = runtime.AllocateEdgeActor();
+
+        auto actorId = runtime.Register(actor.release());
+
+        // One request is postponed
+        runtime.Send(
+            TAutoPtr<IEventHandle>(new IEventHandle(
+                actorId,
+                senderId,
+                new NActors::TEvents::TEvWakeup())));
+
+        // Flush is initiated
+        runtime.Send(
+            TAutoPtr<IEventHandle>(new IEventHandle(
+                actorId,
+                senderId,
+                new NActors::TEvents::TEvFlushLog())));
+    }
+}
+
+}   // namespace NCloud

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

@@ -1,8 +1,19 @@
 UNITTEST_FOR(cloud/storage/core/libs/throttling)
 
+INCLUDE(${ARCADIA_ROOT}/cloud/storage/core/tests/recipes/small.inc)
+
+SPLIT_FACTOR(1)
+
 SRCS(
     helpers_ut.cpp
     leaky_bucket_ut.cpp
+    tablet_throttler_ut.cpp
+)
+
+PEERDIR(
+    contrib/ydb/core/testlib
+    contrib/ydb/core/testlib/basics
+    contrib/ydb/core/testlib/default
 )
 
 END()