rename class and move in common

7 files changed, 151 insertions, 56 deletions

diff --git a/ydb/core/tx/conveyor/service/service.cpp b/ydb/core/tx/conveyor/service/service.cpp
index bf9f5ea647d..5c9d7852609 100644
--- a/ydb/core/tx/conveyor/service/service.cpp
+++ b/ydb/core/tx/conveyor/service/service.cpp
@@ -42,9 +42,9 @@ void TDistributor::HandleMain(TEvInternal::TEvTaskProcessedResult::TPtr& ev) {
     } else {
         Workers.emplace_back(ev->Sender);
     }
-    if (ev->Get()->GetErrorMessage()) {
+    if (ev->Get()->IsFail()) {
         ALS_ERROR(NKikimrServices::TX_CONVEYOR) << "action=on_error;owner=" << ev->Get()->GetOwnerId() << ";workers=" << Workers.size() << ";waiting=" << Waiting.size();
-        Send(ev->Get()->GetOwnerId(), new TEvExecution::TEvTaskProcessedResult(ev->Get()->GetErrorMessage()));
+        Send(ev->Get()->GetOwnerId(), new TEvExecution::TEvTaskProcessedResult(ev->Get()->GetError()));
     } else {
         Send(ev->Get()->GetOwnerId(), new TEvExecution::TEvTaskProcessedResult(ev->Get()->GetResult()));
     }
@@ -64,8 +64,9 @@ void TDistributor::HandleMain(TEvExecution::TEvNewTask::TPtr& ev) {
     } else {
         ALS_ERROR(NKikimrServices::TX_CONVEYOR) << "action=overlimit;sender=" << ev->Sender << ";workers=" << Workers.size() << ";waiting=" << Waiting.size();
         OverlimitRate->Inc();
-        Send(ev->Sender, new TEvExecution::TEvTaskProcessedResult("scan conveyor overloaded (" +
-            ::ToString(Waiting.size()) + " >= " + ::ToString(Config.GetQueueSizeLimit()) + ")"));
+        Send(ev->Sender, new TEvExecution::TEvTaskProcessedResult(
+            TConclusionStatus::Fail("scan conveyor overloaded (" + ::ToString(Waiting.size()) + " >= " + ::ToString(Config.GetQueueSizeLimit()) + ")")
+        ));
     }
     WaitingQueueSize->Set(Waiting.size());
     WorkersCount->Set(Workers.size());
diff --git a/ydb/core/tx/conveyor/service/worker.h b/ydb/core/tx/conveyor/service/worker.h
index 280b0c43e25..53eda8cb4cf 100644
--- a/ydb/core/tx/conveyor/service/worker.h
+++ b/ydb/core/tx/conveyor/service/worker.h
@@ -5,7 +5,7 @@
 #include <ydb/library/accessor/accessor.h>
 #include <ydb/core/tx/conveyor/usage/abstract.h>
 #include <ydb/core/protos/services.pb.h>
-#include <ydb/services/metadata/request/common.h>
+#include <ydb/library/conclusion/result.h>
 #include <library/cpp/actors/core/log.h>
 #include <library/cpp/actors/core/hfunc.h>
 
@@ -29,12 +29,12 @@ public:
 
 struct TEvInternal {
     enum EEv {
-        EvNewTask = EventSpaceBegin(TEvents::ES_PRIVATE),
+        EvNewTask = EventSpaceBegin(NActors::TEvents::ES_PRIVATE),
         EvTaskProcessedResult,
         EvEnd
     };
 
-    static_assert(EvEnd < EventSpaceEnd(TEvents::ES_PRIVATE), "expected EvEnd < EventSpaceEnd");
+    static_assert(EvEnd < EventSpaceEnd(NActors::TEvents::ES_PRIVATE), "expected EvEnd < EventSpaceEnd");
 
     class TEvNewTask: public NActors::TEventLocal<TEvNewTask, EvNewTask> {
     private:
@@ -53,13 +53,13 @@ struct TEvInternal {
 
     class TEvTaskProcessedResult:
         public NActors::TEventLocal<TEvTaskProcessedResult, EvTaskProcessedResult>,
-        public NMetadata::NRequest::TMaybeResult<ITask::TPtr> {
+        public TConclusion<ITask::TPtr> {
     private:
-        using TBase = NMetadata::NRequest::TMaybeResult<ITask::TPtr>;
+        using TBase = TConclusion<ITask::TPtr>;
         YDB_READONLY_DEF(NActors::TActorId, OwnerId);
     public:
         TEvTaskProcessedResult(const NActors::TActorId& ownerId, const TString& errorMessage)
-            : TBase(errorMessage)
+            : TBase(TConclusionStatus::Fail(errorMessage))
             , OwnerId(ownerId) {
 
         }
diff --git a/ydb/core/tx/conveyor/usage/events.h b/ydb/core/tx/conveyor/usage/events.h
index 12ab77bd5c6..38f3539c39d 100644
--- a/ydb/core/tx/conveyor/usage/events.h
+++ b/ydb/core/tx/conveyor/usage/events.h
@@ -2,7 +2,8 @@
 #include "abstract.h"
 #include <library/cpp/actors/core/event_local.h>
 #include <library/cpp/actors/core/events.h>
-#include <ydb/services/metadata/request/common.h>
+#include <ydb/library/conclusion/result.h>
+#include <ydb/core/base/events.h>
 
 namespace NKikimr::NConveyor {
 
@@ -28,9 +29,9 @@ struct TEvExecution {
 
     class TEvTaskProcessedResult:
         public NActors::TEventLocal<TEvTaskProcessedResult, EvTaskProcessedResult>,
-        public NMetadata::NRequest::TMaybeResult<ITask::TPtr> {
+        public TConclusion<ITask::TPtr> {
     private:
-        using TBase = NMetadata::NRequest::TMaybeResult<ITask::TPtr>;
+        using TBase = TConclusion<ITask::TPtr>;
     public:
         using TBase::TBase;
     };
diff --git a/ydb/library/conclusion/result.h b/ydb/library/conclusion/result.h
new file mode 100644
index 00000000000..3a685845bc2
--- /dev/null
+++ b/ydb/library/conclusion/result.h
@@ -0,0 +1,75 @@
+#pragma once
+#include "status.h"
+#include <util/system/yassert.h>
+#include <optional>
+
+namespace NKikimr {
+
+template <class TResult>
+class TConclusion {
+private:
+    std::variant<TConclusionStatus, TResult> Result;
+public:
+
+    TConclusion(TConclusionStatus&& status)
+        : Result(std::move(status)) {
+        auto* resStatus = std::get_if<TConclusionStatus>(&Result);
+        Y_VERIFY(resStatus->IsFail());
+    }
+
+    bool IsFail() const {
+        return std::get_if<TConclusionStatus>(&Result);
+    }
+
+    bool IsSuccess() const {
+        return std::get_if<TResult>(&Result);
+    }
+
+    TConclusion(const TConclusionStatus& status)
+        : Result(status) {
+        Y_VERIFY(IsFail());
+    }
+
+    TConclusion(TResult&& result)
+        : Result(std::move(result)) {
+    }
+
+    TConclusion(const TResult& result)
+        : Result(result) {
+    }
+
+    const TConclusionStatus& GetError() const {
+        auto result = std::get_if<TConclusionStatus>(&Result);
+        Y_VERIFY(result, "incorrect object for error request");
+        return *result;
+    }
+
+    const TResult& GetResult() const {
+        auto result = std::get_if<TResult>(&Result);
+        Y_VERIFY(result, "incorrect object for result request");
+        return *result;
+    }
+
+    const TResult& operator*() const {
+        return GetResult();
+    }
+
+    bool operator!() const {
+        return IsFail();
+    }
+
+    explicit operator bool() const {
+        return IsSuccess();
+    }
+
+    const TString& GetErrorMessage() const {
+        auto* status = std::get_if<TConclusionStatus>(&Result);
+        if (!status) {
+            return Default<TString>();
+        } else {
+            return status->GetErrorMessage();
+        }
+    }
+};
+
+}
diff --git a/ydb/library/conclusion/status.h b/ydb/library/conclusion/status.h
new file mode 100644
index 00000000000..739d5d86a10
--- /dev/null
+++ b/ydb/library/conclusion/status.h
@@ -0,0 +1,55 @@
+#pragma once
+#include <util/generic/string.h>
+#include <optional>
+
+namespace NKikimr {
+
+class TConclusionStatus {
+private:
+    std::optional<TString> ErrorMessage;
+    TConclusionStatus() = default;
+    TConclusionStatus(const TString& errorMessage)
+        : ErrorMessage(errorMessage) {
+        Y_VERIFY(!!ErrorMessage);
+    }
+
+    TConclusionStatus(const char* errorMessage)
+        : ErrorMessage(errorMessage) {
+        Y_VERIFY(!!ErrorMessage);
+    }
+public:
+
+    const TString& GetErrorMessage() const {
+        return ErrorMessage ? *ErrorMessage : Default<TString>();
+    }
+
+    static TConclusionStatus Fail(const char* errorMessage) {
+        return TConclusionStatus(errorMessage);
+    }
+
+    static TConclusionStatus Fail(const TString& errorMessage) {
+        return TConclusionStatus(errorMessage);
+    }
+
+    bool IsFail() const {
+        return !Ok();
+    }
+
+    bool Ok() const {
+        return !ErrorMessage;
+    }
+
+    bool operator!() const {
+        return !!ErrorMessage;
+    }
+
+    explicit operator bool() const {
+        return Ok();
+    }
+
+    static TConclusionStatus Success() {
+        return TConclusionStatus();
+    }
+};
+
+}
diff --git a/ydb/services/metadata/request/common.h b/ydb/services/metadata/request/common.h
index 3f00c3634c7..47d65dd34f1 100644
--- a/ydb/services/metadata/request/common.h
+++ b/ydb/services/metadata/request/common.h
@@ -112,44 +112,6 @@ public:
     }
 };
 
-template <class TResult>
-class TMaybeResult {
-private:
-    YDB_READONLY_DEF(TString, ErrorMessage);
-    YDB_ACCESSOR_DEF(TResult, Result);
-public:
-    TMaybeResult(const TString& errorMessage)
-        : ErrorMessage(errorMessage) {
-
-    }
-
-    TMaybeResult(const char* errorMessage)
-        : ErrorMessage(errorMessage) {
-
-    }
-
-    TMaybeResult(TResult&& result)
-        : Result(std::move(result)) {
-
-    }
-
-    TMaybeResult(const TResult& result)
-        : Result(result) {
-
-    }
-
-    const TResult& operator*() const {
-        Y_ENSURE(!ErrorMessage, yexception() << "incorrect object for result request");
-        return Result;
-    }
-
-    bool operator!() const {
-        return !!ErrorMessage;
-    }
-
-
-};
-
 template <class TDialogPolicy>
 class TEvRequestResult: public NActors::TEventLocal<TEvRequestResult<TDialogPolicy>, TDialogPolicy::EvResult> {
 private:
diff --git a/ydb/services/metadata/request/request_actor_cb.h b/ydb/services/metadata/request/request_actor_cb.h
index a1e747d48cc..f13b71d7fbb 100644
--- a/ydb/services/metadata/request/request_actor_cb.h
+++ b/ydb/services/metadata/request/request_actor_cb.h
@@ -10,6 +10,7 @@
 #include <ydb/library/aclib/aclib.h>
 #include <ydb/library/yql/public/issue/yql_issue_message.h>
 #include <ydb/library/yql/public/issue/yql_issue.h>
+#include <ydb/library/conclusion/result.h>
 
 namespace NKikimr::NMetadata::NRequest {
 
@@ -63,15 +64,15 @@ private:
     std::shared_ptr<TNextController> NextController;
     const NACLib::TUserToken UserToken;
 protected:
-    TMaybeResult<typename TNextController::TDialogPolicy::TRequest> BuildNextRequest(typename TCurrentDialogPolicy::TResponse&& result) const {
+    TConclusion<typename TNextController::TDialogPolicy::TRequest> BuildNextRequest(typename TCurrentDialogPolicy::TResponse&& result) const {
         return DoBuildNextRequest(std::move(result));
     }
 
-    virtual TMaybeResult<typename TNextController::TDialogPolicy::TRequest> DoBuildNextRequest(typename TCurrentDialogPolicy::TResponse&& result) const = 0;
+    virtual TConclusion<typename TNextController::TDialogPolicy::TRequest> DoBuildNextRequest(typename TCurrentDialogPolicy::TResponse&& result) const = 0;
 public:
     using TDialogPolicy = TCurrentDialogPolicy;
     virtual void OnRequestResult(typename TCurrentDialogPolicy::TResponse&& result) override {
-        TMaybeResult<typename TNextController::TDialogPolicy::TRequest> nextRequest = BuildNextRequest(std::move(result));
+        TConclusion<typename TNextController::TDialogPolicy::TRequest> nextRequest = BuildNextRequest(std::move(result));
         if (!nextRequest) {
             OnRequestFailed(nextRequest.GetErrorMessage());
         } else {
@@ -97,14 +98,14 @@ private:
     using TBase = IChainController<TDialogCreateSession, IExternalController<TDialogPolicy>>;
     TRequest ProtoRequest;
 protected:
-    virtual TMaybeResult<typename TDialogPolicy::TRequest> DoBuildNextRequest(TDialogCreateSession::TResponse&& response) const override {
+    virtual TConclusion<typename TDialogPolicy::TRequest> DoBuildNextRequest(TDialogCreateSession::TResponse&& response) const override {
         auto result = ProtoRequest;
         Ydb::Table::CreateSessionResponse currentFullReply = std::move(response);
         Ydb::Table::CreateSessionResult session;
         currentFullReply.operation().result().UnpackTo(&session);
         const TString sessionId = session.session_id();
         if (!sessionId) {
-            return "cannot build session for request";
+            return TConclusionStatus::Fail("cannot build session for request");
         }
         result.set_session_id(sessionId);
         return result;