Fixed possible stop of reading from the topic partition (ydb-platform#15288)

Author: nshestakov

ydb/core/persqueue/partition.h

@@ -240,6 +240,7 @@ class TPartition : public TActorBootstrapped<TPartition> {
     void ProcessChangeOwnerRequest(TAutoPtr<TEvPQ::TEvChangeOwner> ev, const TActorContext& ctx);
     void ProcessChangeOwnerRequests(const TActorContext& ctx);
     void ProcessHasDataRequests(const TActorContext& ctx);
+    bool ProcessHasDataRequest(const THasDataReq& request, const TActorContext& ctx);
     void ProcessRead(const TActorContext& ctx, TReadInfo&& info, const ui64 cookie, bool subscription);
     void ProcessReserveRequests(const TActorContext& ctx);
     void ProcessTimestampRead(const TActorContext& ctx);

ydb/core/persqueue/partition_read.cpp

@@ -135,6 +135,32 @@ TAutoPtr<TEvPersQueue::TEvHasDataInfoResponse> TPartition::MakeHasDataInfoRespon
     return res;
 }
 
+bool TPartition::ProcessHasDataRequest(const THasDataReq& request, const TActorContext& ctx) {
+    auto sendResponse = [&](ui64 lagSize, bool readingFinished) {
+        auto response = MakeHasDataInfoResponse(lagSize, request.Cookie, readingFinished);
+        ctx.Send(request.Sender, response.Release());
+    };
+
+    if (!IsActive()) {
+        if (request.Offset < EndOffset && (!request.ReadTimestamp || *request.ReadTimestamp <= EndWriteTimestamp)) {
+            sendResponse(GetSizeLag(request.Offset), false);
+        } else {
+            sendResponse(0, true);
+
+            auto now = ctx.Now();
+            auto& userInfo = UsersInfoStorage->GetOrCreate(request.ClientId, ctx);
+            userInfo.UpdateReadOffset((i64)EndOffset - 1, now, now, now, true);          
+        }
+    } else if (request.Offset < EndOffset) {
+        sendResponse(GetSizeLag(request.Offset), false);
+    } else {
+        return false;
+    }
+
+    return true;
+}
+
+
 void TPartition::ProcessHasDataRequests(const TActorContext& ctx) {
     if (!InitDone) {
         return;
@@ -150,13 +176,7 @@ void TPartition::ProcessHasDataRequests(const TActorContext& ctx) {
     };
 
     for (auto request = HasDataRequests.begin(); request != HasDataRequests.end();) {
-        if (request->Offset < EndOffset && (IsActive() || !request->ReadTimestamp || *request->ReadTimestamp < EndWriteTimestamp)) {
-            auto response = MakeHasDataInfoResponse(GetSizeLag(request->Offset), request->Cookie);
-            ctx.Send(request->Sender, response.Release());
-        } else if (!IsActive()) {
-            auto response = MakeHasDataInfoResponse(0, request->Cookie, true);
-            ctx.Send(request->Sender, response.Release());
-        } else {
+        if (!ProcessHasDataRequest(*request, ctx)) {
             break;
         }
 
@@ -185,33 +205,23 @@ void TPartition::Handle(TEvPersQueue::TEvHasDataInfo::TPtr& ev, const TActorCont
     auto& record = ev->Get()->Record;
     Y_ABORT_UNLESS(record.HasSender());
 
-    auto cookie = record.HasCookie() ? TMaybe<ui64>(record.GetCookie()) : TMaybe<ui64>();
+    auto now = ctx.Now();
 
+    auto cookie = record.HasCookie() ? TMaybe<ui64>(record.GetCookie()) : TMaybe<ui64>();
     auto readTimestamp = GetReadFrom(record.GetMaxTimeLagMs(), record.GetReadTimestampMs(), TInstant::Zero() /* TODO */, ctx);
 
     TActorId sender = ActorIdFromProto(record.GetSender());
-    if (InitDone && EndOffset > (ui64)record.GetOffset() && (!readTimestamp || EndWriteTimestamp >= *readTimestamp)) { //already has data, answer right now
-        auto response = MakeHasDataInfoResponse(GetSizeLag(record.GetOffset()), cookie);
-        ctx.Send(sender, response.Release());
-    } else if (InitDone && !IsActive()) {
-        auto now = ctx.Now();
 
-        auto& userInfo = UsersInfoStorage->GetOrCreate(record.GetClientId(), ctx);
-        userInfo.UpdateReadOffset((i64)EndOffset - 1, now, now, now, true);
+    THasDataReq req{++HasDataReqNum, (ui64)record.GetOffset(), sender, cookie,
+        record.HasClientId() && InitDone ? record.GetClientId() : "", readTimestamp};
 
-        auto response = MakeHasDataInfoResponse(0, cookie, true);
-        ctx.Send(sender, response.Release());
-    } else {
-        THasDataReq req{++HasDataReqNum, (ui64)record.GetOffset(), sender, cookie,
-                        record.HasClientId() && InitDone ? record.GetClientId() : "", readTimestamp};
+    if (!InitDone || !ProcessHasDataRequest(req, ctx)) {
         THasDataDeadline dl{TInstant::MilliSeconds(record.GetDeadline()), req};
-        auto res = HasDataRequests.insert(req);
+        auto res = HasDataRequests.insert(std::move(req));
         HasDataDeadlines.insert(dl);
         Y_ABORT_UNLESS(res.second);
 
         if (InitDone && record.HasClientId() && !record.GetClientId().empty()) {
-            auto now = ctx.Now();
-
             auto& userInfo = UsersInfoStorage->GetOrCreate(record.GetClientId(), ctx);
             ++userInfo.Subscriptions;
             userInfo.UpdateReadOffset((i64)EndOffset - 1, now, now, now);

ydb/core/persqueue/partition_util.h

@@ -116,7 +116,7 @@ struct TPartition::THasDataReq {
     TMaybe<TInstant> ReadTimestamp;
 
     bool operator < (const THasDataReq& req) const {
-        return Num < req.Num;
+        return std::tuple(Offset, Num) < std::tuple(req.Offset, req.Num);
     }
 };