Make result optional

![](https://arcanum.s3.mds.yandex.net/files/azevaykin/4jrvVFCuPxsw1d9E3tgJs)
Убрал холостое создание std::pair<TKey, TString> в https://a.yandex-team.ru/review/3914273/files/b77e3d7a98463098bb5e0e1ef176d5fd2339c054#file-ydb/core/persqueue/blob.cpp:L783

4 files changed, 23 insertions, 23 deletions

diff --git a/ydb/core/persqueue/blob.cpp b/ydb/core/persqueue/blob.cpp
index 859eafa43bc..60f2f967089 100644
--- a/ydb/core/persqueue/blob.cpp
+++ b/ydb/core/persqueue/blob.cpp
@@ -783,11 +783,10 @@ TString TPartitionedBlob::CompactHead(bool glueHead, THead& head, bool glueNewHe
     return valueD;
 }
 
-std::pair<TKey, TString> TPartitionedBlob::Add(TClientBlob&& blob)
+std::optional<std::pair<TKey, TString>> TPartitionedBlob::Add(TClientBlob&& blob)
 {
     Y_VERIFY(NewHead.Offset >= Head.Offset);
     ui32 size = blob.GetBlobSize();
-    std::pair<TKey, TString> res;
     Y_VERIFY(InternalPartsCount < 1000); //just check for future packing
     if (HeadSize + BlobsSize + size + GetMaxHeaderSize() > MaxBlobSize)
         NeedCompactHead = true;
@@ -795,7 +794,8 @@ std::pair<TKey, TString> TPartitionedBlob::Add(TClientBlob&& blob)
         NeedCompactHead = false;
     }
 
-    if (NeedCompactHead) { //need form blob without last chunk, on start or in case of big head
+    std::optional<std::pair<TKey, TString>> res;
+    if (NeedCompactHead) { // need form blob without last chunk, on start or in case of big head
         NeedCompactHead = false;
         HeadPartNo = NextPartNo;
         ui32 count = (GlueHead ? Head.GetCount() : 0) + (GlueNewHead ? NewHead.GetCount() : 0);
@@ -804,7 +804,7 @@ std::pair<TKey, TString> TPartitionedBlob::Add(TClientBlob&& blob)
 
         Y_VERIFY(NewHead.GetNextOffset() >= (GlueHead ? Head.Offset : NewHead.Offset));
 
-        res.first = TKey(TKeyPrefix::TypeTmpData, Partition, StartOffset, StartPartNo, count, InternalPartsCount, false);
+        TKey key(TKeyPrefix::TypeTmpData, Partition, StartOffset, StartPartNo, count, InternalPartsCount, false);
 
         StartOffset = Offset;
         StartPartNo = NextPartNo;
@@ -820,14 +820,15 @@ std::pair<TKey, TString> TPartitionedBlob::Add(TClientBlob&& blob)
             Y_VERIFY(batch.Packed);
             batch.SerializeTo(valueD);
         }
-        res.second = valueD;
-        Y_VERIFY(res.second.size() <= MaxBlobSize && (res.second.size() + size + 1_MB > MaxBlobSize
-                    || HeadSize + BlobsSize + size + GetMaxHeaderSize() <= MaxBlobSize));
+
+        Y_VERIFY(valueD.size() <= MaxBlobSize && (valueD.size() + size + 1_MB > MaxBlobSize || HeadSize + BlobsSize + size + GetMaxHeaderSize() <= MaxBlobSize));
         HeadSize = 0;
         BlobsSize = 0;
-        CheckBlob(res.first, res.second);
-        FormedBlobs.push_back(std::make_pair(res.first, res.second.size()));
+        CheckBlob(key, valueD);
+        FormedBlobs.emplace_back(key, valueD.size());
         Blobs.clear();
+
+        res = {key, valueD};
     }
     BlobsSize += size + GetMaxHeaderSize();
     ++NextPartNo;
diff --git a/ydb/core/persqueue/blob.h b/ydb/core/persqueue/blob.h
index 5f9ef43914f..6573ee4720f 100644
--- a/ydb/core/persqueue/blob.h
+++ b/ydb/core/persqueue/blob.h
@@ -267,8 +267,7 @@ public:
     TPartitionedBlob(const ui32 partition, const ui64 offset, const TString& sourceId, const ui64 seqNo,
                      const ui16 totalParts, const ui32 totalSize, THead& head, THead& newHead, bool headCleared, bool needCompactHead, const ui32 maxBlobSize);
 
-
-    std::pair<TKey, TString> Add(TClientBlob&& blob);
+    std::optional<std::pair<TKey, TString>> Add(TClientBlob&& blob);
 
     bool IsInited() const { return !SourceId.empty(); }
 
diff --git a/ydb/core/persqueue/partition_write.cpp b/ydb/core/persqueue/partition_write.cpp
index c9910b8d4f9..05b335fd804 100644
--- a/ydb/core/persqueue/partition_write.cpp
+++ b/ydb/core/persqueue/partition_write.cpp
@@ -966,21 +966,21 @@ bool TPartition::AppendHeadWithNewWrites(TEvKeyValue::TEvRequest* request, const
         bool lastBlobPart = blob.IsLastPart();
 
         //will return compacted tmp blob
-        std::pair<TKey, TString> newWrite = PartitionedBlob.Add(std::move(blob));
+        auto newWrite = PartitionedBlob.Add(std::move(blob));
 
-        if (!newWrite.second.empty()) {
+        if (newWrite && !newWrite->second.empty()) {
             auto write = request->Record.AddCmdWrite();
-            write->SetKey(newWrite.first.Data(), newWrite.first.Size());
-            write->SetValue(newWrite.second);
-            Y_VERIFY(!newWrite.first.IsHead());
-            auto channel = GetChannel(NextChannel(newWrite.first.IsHead(), newWrite.second.Size()));
+            write->SetKey(newWrite->first.Data(), newWrite->first.Size());
+            write->SetValue(newWrite->second);
+            Y_VERIFY(!newWrite->first.IsHead());
+            auto channel = GetChannel(NextChannel(newWrite->first.IsHead(), newWrite->second.Size()));
             write->SetStorageChannel(channel);
             write->SetTactic(AppData(ctx)->PQConfig.GetTactic());
 
-            TKey resKey = newWrite.first;
+            TKey resKey = newWrite->first;
             resKey.SetType(TKeyPrefix::TypeData);
             write->SetKeyToCache(resKey.Data(), resKey.Size());
-            WriteCycleSize += newWrite.second.size();
+            WriteCycleSize += newWrite->second.size();
 
             LOG_DEBUG_S(
                     ctx, NKikimrServices::PERSQUEUE,
@@ -988,8 +988,8 @@ bool TPartition::AppendHeadWithNewWrites(TEvKeyValue::TEvRequest* request, const
                         "' partition " << Partition <<
                         " part blob sourceId '" << EscapeC(p.Msg.SourceId) <<
                         "' seqNo " << p.Msg.SeqNo << " partNo " << p.Msg.PartNo <<
-                        " result is " << TStringBuf(newWrite.first.Data(), newWrite.first.Size()) <<
-                        " size " << newWrite.second.size()
+                        " result is " << TStringBuf(newWrite->first.Data(), newWrite->first.Size()) <<
+                        " size " << newWrite->second.size()
             );
         }
 
diff --git a/ydb/core/persqueue/ut/internals_ut.cpp b/ydb/core/persqueue/ut/internals_ut.cpp
index 22db0517609..7f953e042d5 100644
--- a/ydb/core/persqueue/ut/internals_ut.cpp
+++ b/ydb/core/persqueue/ut/internals_ut.cpp
@@ -88,8 +88,8 @@ void Test(bool headCompacted, ui32 parts, ui32 partSize, ui32 leftInHead)
         );
         all.push_back(clientBlob);
         auto res = blob.Add(std::move(clientBlob));
-        if (!res.second.empty())
-            formed.push_back(res);
+        if (res && !res->second.empty())
+            formed.push_back(*res);
     }
     UNIT_ASSERT(blob.IsComplete());
     UNIT_ASSERT(formed.size() == blob.GetFormedBlobs().size());