[Backport stable-25-3-1] PR #30261: Separate DeleteQueue to allow reusing only current-generation locators (#30272)

Author: ydbot

ydb/core/blob_depot/data_load.cpp

@@ -110,12 +110,16 @@ namespace NKikimr::NBlobDepot {
         if (!rows.IsReady()) {
             return false;
         }
+        const ui32 generation = Self->Executor()->Generation();
         while (rows.IsValid()) {
             TS3Locator item{
                 .Len = rows.GetValue<Schema::TrashS3::Len>(),
                 .Generation = rows.GetValue<Schema::TrashS3::Generation>(),
                 .KeyId = rows.GetValue<Schema::TrashS3::KeyId>(),
             };
+            if (item.Generation == generation) {
+                return true; // we don't want to read newly added items by this tablet's generation
+            }
             if (item != from) {
                 Self->S3Manager->AddTrashToCollect(item);
                 from = item;

ydb/core/blob_depot/s3.h

@@ -69,7 +69,9 @@ namespace NKikimr::NBlobDepot {
         static constexpr ui32 MaxDeletesInFlight = 3;
         static constexpr size_t MaxObjectsToDeleteAtOnce = 10;
 
-        std::deque<TS3Locator> DeleteQueue; // items we are definitely going to delete (must be present in TrashS3)
+        // items we are definitely going to delete (must be present in TrashS3)
+        std::deque<TS3Locator> DeleteQueueInPrevGenerations;
+        std::deque<TS3Locator> DeleteQueueInCurrentGeneration;
         THashSet<TActorId> ActiveDeleters;
         ui32 NumDeleteTxInFlight = 0;
         ui64 TotalS3TrashObjects = 0;

ydb/core/blob_depot/s3_delete.cpp

@@ -156,18 +156,28 @@ namespace NKikimr::NBlobDepot {
         STLOG(PRI_INFO, BLOB_DEPOT, BDTS06, "AddTrashToCollect", (Id, Self->GetLogId()), (Locator, locator));
         Self->TabletCounters->Simple()[NKikimrBlobDepot::COUNTER_TOTAL_S3_TRASH_OBJECTS] = ++TotalS3TrashObjects;
         Self->TabletCounters->Simple()[NKikimrBlobDepot::COUNTER_TOTAL_S3_TRASH_SIZE] = TotalS3TrashSize += locator.Len;
-        DeleteQueue.push_back(locator);
+        if (const ui32 generation = Self->Executor()->Generation(); locator.Generation < generation) {
+            DeleteQueueInPrevGenerations.push_back(locator);
+        } else {
+            Y_DEBUG_ABORT_UNLESS(locator.Generation == generation);
+            DeleteQueueInCurrentGeneration.push_back(locator);
+        }
         RunDeletersIfNeeded();
     }
 
     void TS3Manager::RunDeletersIfNeeded() {
-        while (!DeleteQueue.empty() && NumDeleteTxInFlight + ActiveDeleters.size() < MaxDeletesInFlight) {
+        while (NumDeleteTxInFlight + ActiveDeleters.size() < MaxDeletesInFlight) {
+            // create list of locators we are going to delete during this operation
             THashMap<TString, TS3Locator> locators;
-
-            while (!DeleteQueue.empty() && locators.size() < MaxObjectsToDeleteAtOnce) {
-                const TS3Locator& locator = DeleteQueue.front();
-                locators.emplace(locator.MakeObjectName(BasePath), locator);
-                DeleteQueue.pop_front();
+            for (auto *queue : {&DeleteQueueInPrevGenerations, &DeleteQueueInCurrentGeneration}) {
+                while (!queue->empty() && locators.size() < MaxObjectsToDeleteAtOnce) {
+                    const TS3Locator& locator = queue->front();
+                    locators.emplace(locator.MakeObjectName(BasePath), locator);
+                    queue->pop_front();
+                }
+            }
+            if (!locators) {
+                break;
             }
 
             const TActorId actorId = Self->Register(new TDeleterActor(Self->SelfId(), locators, Self->GetLogId()));
@@ -218,7 +228,15 @@ namespace NKikimr::NBlobDepot {
                 }
 
                 if (!msg.LocatorsError.empty()) {
-                    DeleteQueue.insert(DeleteQueue.end(), msg.LocatorsError.begin(), msg.LocatorsError.end());
+                    const ui32 generation = Self->Executor()->Generation();
+                    for (auto& locator : msg.LocatorsError) {
+                        if (locator.Generation < generation) {
+                            DeleteQueueInPrevGenerations.push_back(locator);
+                        } else {
+                            Y_DEBUG_ABORT_UNLESS(locator.Generation == generation);
+                            DeleteQueueInCurrentGeneration.push_back(locator);
+                        }
+                    }
                     RunDeletersIfNeeded();
                 }
             })

ydb/core/blob_depot/s3_write.cpp

@@ -98,9 +98,9 @@ namespace NKikimr::NBlobDepot {
     };
 
     TS3Locator TS3Manager::AllocateS3Locator(ui32 len) {
-        if (!DeleteQueue.empty()) {
-            TS3Locator res = DeleteQueue.front();
-            DeleteQueue.pop_front();
+        if (!DeleteQueueInCurrentGeneration.empty()) {
+            TS3Locator res = DeleteQueueInCurrentGeneration.front();
+            DeleteQueueInCurrentGeneration.pop_front();
             Self->TabletCounters->Simple()[NKikimrBlobDepot::COUNTER_TOTAL_S3_TRASH_OBJECTS] = --TotalS3TrashObjects;
             Self->TabletCounters->Simple()[NKikimrBlobDepot::COUNTER_TOTAL_S3_TRASH_SIZE] = TotalS3TrashSize -= res.Len;
             res.Len = len;