collectgarbage for compactcas and structured cache uses shared implementation

5 files changed, 202 insertions, 543 deletions

diff --git a/zenserver/cache/structuredcachestore.cpp b/zenserver/cache/structuredcachestore.cpp
index 53a479edb..d313cd0c2 100644
--- a/zenserver/cache/structuredcachestore.cpp
+++ b/zenserver/cache/structuredcachestore.cpp
@@ -127,25 +127,9 @@ namespace {
 
 	static_assert(sizeof(LegacyDiskIndexEntry) == 36);
 
-	const char* IndexExtension = ".uidx";
-	const char* LogExtension   = ".slog";
-	const char* DataExtension  = ".sobs";
-
-	std::filesystem::path GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint32_t BlockIndex)
-	{
-		ExtendablePathBuilder<256> Path;
-
-		char BlockHexString[9];
-		ToHexNumber(BlockIndex, BlockHexString);
-
-		Path.Append(BlocksBasePath);
-		Path.AppendSeparator();
-		Path.AppendAsciiRange(BlockHexString, BlockHexString + 4);
-		Path.AppendSeparator();
-		Path.Append(BlockHexString);
-		Path.Append(DataExtension);
-		return Path.ToPath();
-	}
+	const char* IndexExtension		= ".uidx";
+	const char* LogExtension		= ".slog";
+	const char* LegacyDataExtension = ".sobs";
 
 	std::filesystem::path GetIndexPath(const std::filesystem::path& BucketDir, const std::string& BucketName)
 	{
@@ -169,7 +153,7 @@ namespace {
 
 	std::filesystem::path GetLegacyDataPath(const std::filesystem::path& BucketDir)
 	{
-		return BucketDir / (std::string("zen") + DataExtension);
+		return BucketDir / (std::string("zen") + LegacyDataExtension);
 	}
 
 	std::vector<DiskIndexEntry> MakeDiskIndexEntries(const std::unordered_map<IoHash, DiskLocation>& MovedChunks,
@@ -718,8 +702,6 @@ ZenCacheDiskLayer::CacheBucket::MakeIndexSnapshot()
 		std::vector<DiskIndexEntry> Entries;
 
 		{
-			RwLock::SharedLockScope __(m_InsertLock);
-			RwLock::SharedLockScope ___(m_IndexLock);
 			Entries.resize(m_Index.size());
 
 			uint64_t EntryIndex = 0;
@@ -896,7 +878,7 @@ ZenCacheDiskLayer::CacheBucket::MigrateLegacyData(bool CleanSource)
 	});
 
 	uint32_t WriteBlockIndex = 0;
-	while (std::filesystem::exists(GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
+	while (std::filesystem::exists(BlockStore ::GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
 	{
 		++WriteBlockIndex;
 	}
@@ -1083,7 +1065,7 @@ ZenCacheDiskLayer::CacheBucket::MigrateLegacyData(bool CleanSource)
 			}
 			LogEntries.push_back({.Key = Entry.second.Key, .Location = NewLocation});
 		}
-		std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, WriteBlockIndex);
+		std::filesystem::path BlockPath = BlockStore ::GetBlockPath(m_BlocksBasePath, WriteBlockIndex);
 		CreateDirectories(BlockPath.parent_path());
 		BlockFile.Close();
 		std::filesystem::rename(LegacyDataPath, BlockPath);
@@ -1152,7 +1134,7 @@ ZenCacheDiskLayer::CacheBucket::MigrateLegacyData(bool CleanSource)
 				BlockRanges.push_back(BlockRange);
 
 				WriteBlockIndex++;
-				while (std::filesystem::exists(GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
+				while (std::filesystem::exists(BlockStore ::GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
 				{
 					++WriteBlockIndex;
 				}
@@ -1191,7 +1173,7 @@ ZenCacheDiskLayer::CacheBucket::MigrateLegacyData(bool CleanSource)
 						 NiceTimeSpanMs(ETA));
 			}
 
-			std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, BlockRange.BlockIndex);
+			std::filesystem::path BlockPath = BlockStore ::GetBlockPath(m_BlocksBasePath, BlockRange.BlockIndex);
 			BlockStoreFile		  ChunkBlock(BlockPath);
 			ChunkBlock.Create(BlockRange.BlockSize);
 			uint64_t Offset = 0;
@@ -1299,7 +1281,8 @@ ZenCacheDiskLayer::CacheBucket::OpenLog(const fs::path& BucketDir, const bool Is
 
 	m_SlogFile.Open(LogPath, CasLogFile::Mode::kWrite);
 
-	std::unordered_set<uint32_t> KnownBlocks;
+	std::vector<BlockStoreLocation> KnownLocations;
+	KnownLocations.reserve(m_Index.size());
 	for (const auto& Entry : m_Index)
 	{
 		const DiskLocation& Location = Entry.second.Location;
@@ -1308,62 +1291,11 @@ ZenCacheDiskLayer::CacheBucket::OpenLog(const fs::path& BucketDir, const bool Is
 		{
 			continue;
 		}
-		KnownBlocks.insert(Location.GetBlockLocation(m_PayloadAlignment).BlockIndex);
+		const BlockStoreLocation& BlockLocation = Location.GetBlockLocation(m_PayloadAlignment);
+		KnownLocations.push_back(BlockLocation);
 	}
 
-	if (std::filesystem::is_directory(m_BlocksBasePath))
-	{
-		std::vector<std::filesystem::path> FoldersToScan;
-		FoldersToScan.push_back(m_BlocksBasePath);
-		size_t FolderOffset = 0;
-		while (FolderOffset < FoldersToScan.size())
-		{
-			for (const std::filesystem::directory_entry& Entry : std::filesystem::directory_iterator(FoldersToScan[FolderOffset]))
-			{
-				if (Entry.is_directory())
-				{
-					FoldersToScan.push_back(Entry.path());
-					continue;
-				}
-				if (Entry.is_regular_file())
-				{
-					const std::filesystem::path Path = Entry.path();
-					if (Path.extension() != DataExtension)
-					{
-						continue;
-					}
-					std::string FileName = Path.stem().string();
-					uint32_t	BlockIndex;
-					bool		OK = ParseHexNumber(FileName, BlockIndex);
-					if (!OK)
-					{
-						continue;
-					}
-					if (!KnownBlocks.contains(BlockIndex))
-					{
-						// Log removing unreferenced block
-						// Clear out unused blocks
-						ZEN_INFO("removing unused block for '{}' at '{}'", m_BucketDir / m_BucketName, Path);
-						std::error_code Ec;
-						std::filesystem::remove(Path, Ec);
-						if (Ec)
-						{
-							ZEN_WARN("Failed to delete file '{}' reason: '{}'", Path, Ec.message());
-						}
-						continue;
-					}
-					Ref<BlockStoreFile> BlockFile = new BlockStoreFile(Path);
-					BlockFile->Open();
-					m_ChunkBlocks[BlockIndex] = BlockFile;
-				}
-			}
-			++FolderOffset;
-		}
-	}
-	else
-	{
-		CreateDirectories(m_BlocksBasePath);
-	}
+	m_BlockStore.Initialize(m_BlocksBasePath, MaxBlockSize, BlockStoreDiskLocation::MaxBlockIndex + 1, KnownLocations);
 
 	if (IsNew || ((LogEntryCount + LegacyLogEntryCount) > 0))
 	{
@@ -1390,14 +1322,14 @@ ZenCacheDiskLayer::CacheBucket::BuildPath(PathBuilderBase& Path, const IoHash& H
 bool
 ZenCacheDiskLayer::CacheBucket::GetInlineCacheValue(const DiskLocation& Loc, ZenCacheValue& OutValue)
 {
-	if (Loc.IsFlagSet(DiskLocation::kStandaloneFile))
+	BlockStoreLocation Location = Loc.GetBlockLocation(m_PayloadAlignment);
+
+	Ref<BlockStoreFile> ChunkBlock = m_BlockStore.GetChunkBlock(Location);
+	if (!ChunkBlock)
 	{
 		return false;
 	}
 
-	const BlockStoreLocation& Location	 = Loc.GetBlockLocation(m_PayloadAlignment);
-	Ref<BlockStoreFile>		  ChunkBlock = m_ChunkBlocks[Location.BlockIndex];
-
 	OutValue.Value = ChunkBlock->GetChunk(Location.Offset, Location.Size);
 	OutValue.Value.SetContentType(Loc.GetContentType());
 
@@ -1437,15 +1369,17 @@ ZenCacheDiskLayer::CacheBucket::Get(const IoHash& HashKey, ZenCacheValue& OutVal
 	{
 		IndexEntry& Entry = It.value();
 		Entry.LastAccess.store(GcClock::TickCount(), std::memory_order_relaxed);
+		DiskLocation Location = Entry.Location;
+		_.ReleaseNow();
 
-		if (GetInlineCacheValue(Entry.Location, OutValue))
+		if (Location.IsFlagSet(DiskLocation::kStandaloneFile))
+		{
+			return GetStandaloneCacheValue(Location, HashKey, OutValue);
+		}
+		if (GetInlineCacheValue(Location, OutValue))
 		{
 			return true;
 		}
-
-		_.ReleaseNow();
-
-		return GetStandaloneCacheValue(Entry.Location, HashKey, OutValue);
 	}
 
 	return false;
@@ -1463,84 +1397,7 @@ ZenCacheDiskLayer::CacheBucket::Put(const IoHash& HashKey, const ZenCacheValue&
 	{
 		return PutStandaloneCacheValue(HashKey, Value);
 	}
-
-	// Small object put
-
-	uint8_t EntryFlags = 0;
-
-	if (Value.Value.GetContentType() == ZenContentType::kCbObject)
-	{
-		EntryFlags |= DiskLocation::kStructured;
-	}
-	else if (Value.Value.GetContentType() == ZenContentType::kCompressedBinary)
-	{
-		EntryFlags |= DiskLocation::kCompressed;
-	}
-
-	uint64_t ChunkSize = Value.Value.Size();
-
-	uint32_t			WriteBlockIndex;
-	Ref<BlockStoreFile> WriteBlock;
-	uint64_t			InsertOffset;
-
-	{
-		RwLock::ExclusiveLockScope _(m_InsertLock);
-
-		WriteBlockIndex = m_WriteBlockIndex.load(std::memory_order_acquire);
-		bool IsWriting	= m_WriteBlock != nullptr;
-		if (!IsWriting || (m_CurrentInsertOffset + ChunkSize) > MaxBlockSize)
-		{
-			if (m_WriteBlock)
-			{
-				m_WriteBlock = nullptr;
-			}
-			{
-				RwLock::ExclusiveLockScope __(m_IndexLock);
-				if (m_ChunkBlocks.size() == BlockStoreDiskLocation::MaxBlockIndex)
-				{
-					throw std::runtime_error(fmt::format("unable to allocate a new block in '{}'", m_BucketDir / m_BucketName));
-				}
-				WriteBlockIndex += IsWriting ? 1 : 0;
-				while (m_ChunkBlocks.contains(WriteBlockIndex))
-				{
-					WriteBlockIndex = (WriteBlockIndex + 1) & BlockStoreDiskLocation::MaxBlockIndex;
-				}
-				std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, WriteBlockIndex);
-				m_WriteBlock					= new BlockStoreFile(BlockPath);
-				m_ChunkBlocks[WriteBlockIndex]	= m_WriteBlock;
-				m_WriteBlockIndex.store(WriteBlockIndex, std::memory_order_release);
-			}
-			m_CurrentInsertOffset = 0;
-			m_WriteBlock->Create(MaxBlockSize);
-		}
-		InsertOffset		  = m_CurrentInsertOffset;
-		m_CurrentInsertOffset = RoundUp(InsertOffset + ChunkSize, m_PayloadAlignment);
-		WriteBlock			  = m_WriteBlock;
-	}
-
-	DiskLocation Location({.BlockIndex = WriteBlockIndex, .Offset = InsertOffset, .Size = ChunkSize}, m_PayloadAlignment, EntryFlags);
-	const DiskIndexEntry DiskIndexEntry{.Key = HashKey, .Location = Location};
-
-	WriteBlock->Write(Value.Value.Data(), ChunkSize, InsertOffset);
-	m_SlogFile.Append(DiskIndexEntry);
-
-	m_TotalSize.fetch_add(ChunkSize, std::memory_order_seq_cst);
-	{
-		RwLock::ExclusiveLockScope __(m_IndexLock);
-		if (auto It = m_Index.find(HashKey); It != m_Index.end())
-		{
-			// TODO: should check if write is idempotent and bail out if it is?
-			// this would requiring comparing contents on disk unless we add a
-			// content hash to the index entry
-			IndexEntry& Entry = It.value();
-			Entry.Location	  = Location;
-			Entry.LastAccess.store(GcClock::TickCount(), std::memory_order_relaxed);
-		}
-		else
-		{
-			m_Index.insert({HashKey, {Location, GcClock::TickCount()}});
-		}
-	}
+	PutInlineCacheValue(HashKey, Value);
 }
 
 void
@@ -1555,21 +1412,10 @@ ZenCacheDiskLayer::CacheBucket::Drop()
 void
 ZenCacheDiskLayer::CacheBucket::Flush()
 {
-	{
-		RwLock::ExclusiveLockScope _(m_InsertLock);
-		if (m_CurrentInsertOffset > 0)
-		{
-			uint32_t WriteBlockIndex = m_WriteBlockIndex.load(std::memory_order_acquire);
-			WriteBlockIndex			 = (WriteBlockIndex + 1) & BlockStoreDiskLocation::MaxBlockIndex;
-			m_WriteBlock			 = nullptr;
-			m_WriteBlockIndex.store(WriteBlockIndex, std::memory_order_release);
-			m_CurrentInsertOffset = 0;
-		}
-	}
-	RwLock::SharedLockScope _(m_IndexLock);
+	m_BlockStore.Flush();
 
+	RwLock::SharedLockScope _(m_IndexLock);
 	MakeIndexSnapshot();
-
 	SaveManifest();
 }
 
@@ -1615,20 +1461,22 @@ ZenCacheDiskLayer::CacheBucket::Scrub(ScrubContext& Ctx)
 
 			ZenCacheValue Value;
 
-			if (GetInlineCacheValue(Loc, Value))
+			if (Loc.IsFlagSet(DiskLocation::kStandaloneFile))
 			{
-				// Validate contents
+				if (GetInlineCacheValue(Loc, Value))
+				{
+					// Validate contents
+					continue;
+				}
 			}
 			else if (GetStandaloneCacheValue(Loc, HashKey, Value))
 			{
 				// Note: we cannot currently validate contents since we don't
 				// have a content hash!
+				continue;
 			}
-			else
-			{
-				// Value not found
-				BadKeys.push_back(HashKey);
-			}
+			// Value not found
+			BadKeys.push_back(HashKey);
 		}
 	}
 
@@ -1726,18 +1574,23 @@ ZenCacheDiskLayer::CacheBucket::GatherReferences(GcContext& GcCtx)
 					 WriteBlockTimeUs += ElapsedUs;
 					 WriteBlockLongestTimeUs = std::max(ElapsedUs, WriteBlockLongestTimeUs);
 				 });
-				if (!GetInlineCacheValue(Loc, CacheValue))
+				if (Loc.IsFlagSet(DiskLocation::kStandaloneFile))
 				{
-					GetStandaloneCacheValue(Loc, Key, CacheValue);
+					if (!GetStandaloneCacheValue(Loc, Key, CacheValue))
+					{
+						continue;
+					}
+				}
+				else if (!GetInlineCacheValue(Loc, CacheValue))
+				{
+					continue;
 				}
 			}
 
-			if (CacheValue.Value)
-			{
-				ZEN_ASSERT(CacheValue.Value.GetContentType() == ZenContentType::kCbObject);
-				CbObject Obj(SharedBuffer{CacheValue.Value});
-				Obj.IterateAttachments([&Cids](CbFieldView Field) { Cids.push_back(Field.AsAttachment()); });
-			}
+			ZEN_ASSERT(CacheValue.Value);
+			ZEN_ASSERT(CacheValue.Value.GetContentType() == ZenContentType::kCbObject);
+			CbObject Obj(SharedBuffer{CacheValue.Value});
+			Obj.IterateAttachments([&Cids](CbFieldView Field) { Cids.push_back(Field.AsAttachment()); });
 		}
 	}
 
@@ -1797,10 +1650,6 @@ ZenCacheDiskLayer::CacheBucket::CollectGarbage(GcContext& GcCtx)
 
 	m_SlogFile.Flush();
 
-	IndexMap Index;
-	size_t	 BlockCount;
-	uint64_t ExcludeBlockIndex = 0x800000000ull;
-
 	std::span<const IoHash> ExpiredCacheKeys = GcCtx.ExpiredCacheKeys(m_BucketName);
 	std::vector<IoHash>		DeleteCacheKeys;
 	DeleteCacheKeys.reserve(ExpiredCacheKeys.size());
@@ -1816,30 +1665,27 @@ ZenCacheDiskLayer::CacheBucket::CollectGarbage(GcContext& GcCtx)
 		ZEN_INFO("garbage collect SKIPPED, for '{}', no expired cache keys found", m_BucketDir / m_BucketName);
 		return;
 	}
+
+	IndexMap						 Index;
+	BlockStore::ReclaimSnapshotState BlockStoreState;
 	{
-		RwLock::SharedLockScope __(m_InsertLock);
-		RwLock::SharedLockScope ___(m_IndexLock);
+		RwLock::SharedLockScope __(m_IndexLock);
+		Stopwatch				Timer;
+		const auto				____ = MakeGuard([&Timer, &WriteBlockTimeUs, &WriteBlockLongestTimeUs] {
+			 uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
+			 WriteBlockTimeUs += ElapsedUs;
+			 WriteBlockLongestTimeUs = std::max(ElapsedUs, WriteBlockLongestTimeUs);
+		 });
 		{
-			Stopwatch  Timer;
-			const auto ____ = MakeGuard([&Timer, &WriteBlockTimeUs, &WriteBlockLongestTimeUs] {
-				uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
-				WriteBlockTimeUs += ElapsedUs;
-				WriteBlockLongestTimeUs = std::max(ElapsedUs, WriteBlockLongestTimeUs);
-			});
 			if (m_Index.empty())
 			{
 				ZEN_INFO("garbage collect SKIPPED, for '{}', container is empty", m_BucketDir / m_BucketName);
 				return;
 			}
-			if (m_WriteBlock)
-			{
-				ExcludeBlockIndex = m_WriteBlockIndex.load(std::memory_order_acquire);
-			}
-			__.ReleaseNow();
+			BlockStoreState = m_BlockStore.GetReclaimSnapshotState();
 		}
 		SaveManifest();
-		Index	   = m_Index;
-		BlockCount = m_ChunkBlocks.size();
+		Index = m_Index;
 
 		for (const IoHash& Key : DeleteCacheKeys)
 		{
@@ -1936,295 +1782,102 @@ ZenCacheDiskLayer::CacheBucket::CollectGarbage(GcContext& GcCtx)
 	{
 		return;
 	}
-	std::unordered_map<uint32_t, size_t> BlockIndexToChunkMapIndex;
-	std::vector<std::vector<IoHash>>	 KeepChunks;
-	std::vector<std::vector<IoHash>>	 DeleteChunks;
-
-	BlockIndexToChunkMapIndex.reserve(BlockCount);
-	KeepChunks.reserve(BlockCount);
-	DeleteChunks.reserve(BlockCount);
-	size_t GuesstimateCountPerBlock = TotalChunkHashes.size() / BlockCount / 2;
-
-	uint64_t DeleteCount = 0;
-
-	uint64_t NewTotalSize = 0;
+	TotalChunkCount = TotalChunkHashes.size();
 
-	std::unordered_set<IoHash, IoHash::Hasher> Expired;
-	Expired.insert(DeleteCacheKeys.begin(), DeleteCacheKeys.end());
+	std::vector<BlockStoreLocation> ChunkLocations;
+	std::vector<size_t>				KeepChunkIndexes;
+	std::vector<IoHash>				ChunkIndexToChunkHash;
+	ChunkLocations.reserve(TotalChunkCount);
+	ChunkLocations.reserve(TotalChunkCount);
+	ChunkIndexToChunkHash.reserve(TotalChunkCount);
 
 	GcCtx.FilterCas(TotalChunkHashes, [&](const IoHash& ChunkHash, bool Keep) {
-		auto				KeyIt		  = Index.find(ChunkHash);
-		const DiskLocation& Location	  = KeyIt->second.Location;
-		BlockStoreLocation	BlockLocation = Location.GetBlockLocation(m_PayloadAlignment);
-
-		uint32_t BlockIndex = BlockLocation.BlockIndex;
-
-		if (static_cast<uint64_t>(BlockIndex) == ExcludeBlockIndex)
-		{
-			return;
-		}
-
-		auto   BlockIndexPtr = BlockIndexToChunkMapIndex.find(BlockIndex);
-		size_t ChunkMapIndex = 0;
-		if (BlockIndexPtr == BlockIndexToChunkMapIndex.end())
-		{
-			ChunkMapIndex						  = KeepChunks.size();
-			BlockIndexToChunkMapIndex[BlockIndex] = ChunkMapIndex;
-			KeepChunks.resize(ChunkMapIndex + 1);
-			KeepChunks.back().reserve(GuesstimateCountPerBlock);
-			DeleteChunks.resize(ChunkMapIndex + 1);
-			DeleteChunks.back().reserve(GuesstimateCountPerBlock);
-		}
-		else
-		{
-			ChunkMapIndex = BlockIndexPtr->second;
-		}
+		auto				KeyIt		 = Index.find(ChunkHash);
+		const DiskLocation& DiskLocation = KeyIt->second.Location;
+		BlockStoreLocation	Location	 = DiskLocation.GetBlockLocation(m_PayloadAlignment);
+		size_t				ChunkIndex	 = ChunkLocations.size();
+		ChunkLocations.push_back(Location);
+		ChunkIndexToChunkHash[ChunkIndex] = ChunkHash;
 		if (Keep)
 		{
-			std::vector<IoHash>& ChunkMap = KeepChunks[ChunkMapIndex];
-			ChunkMap.push_back(ChunkHash);
-			NewTotalSize += BlockLocation.Size;
-		}
-		else
-		{
-			std::vector<IoHash>& ChunkMap = DeleteChunks[ChunkMapIndex];
-			ChunkMap.push_back(ChunkHash);
-			DeleteCount++;
+			KeepChunkIndexes.push_back(ChunkIndex);
 		}
 	});
 
-	std::unordered_set<uint32_t> BlocksToReWrite;
-	BlocksToReWrite.reserve(BlockIndexToChunkMapIndex.size());
-	for (const auto& Entry : BlockIndexToChunkMapIndex)
-	{
-		uint32_t				   BlockIndex	 = Entry.first;
-		size_t					   ChunkMapIndex = Entry.second;
-		const std::vector<IoHash>& ChunkMap		 = DeleteChunks[ChunkMapIndex];
-		if (ChunkMap.empty())
-		{
-			continue;
-		}
-		BlocksToReWrite.insert(BlockIndex);
-	}
+	size_t DeleteCount = TotalChunkCount - KeepChunkIndexes.size();
 
 	const bool PerformDelete = GcCtx.IsDeletionMode() && GcCtx.CollectSmallObjects();
 	if (!PerformDelete)
 	{
+		m_BlockStore.ReclaimSpace(BlockStoreState, ChunkLocations, KeepChunkIndexes, m_PayloadAlignment, true);
 		uint64_t TotalSize = m_TotalSize.load(std::memory_order_relaxed);
 		ZEN_INFO("garbage collect from '{}' DISABLED, found #{} {} chunks of total #{} {}",
 				 m_BucketDir / m_BucketName,
 				 DeleteCount,
-				 NiceBytes(TotalSize - NewTotalSize),
+				 0,	 // NiceBytes(TotalSize - NewTotalSize),
 				 TotalChunkCount,
 				 NiceBytes(TotalSize));
 		return;
 	}
 
-	auto AddToDeleted = [this, &Index, &DeletedCount, &DeletedSize](const std::vector<IoHash>& DeletedEntries) {
-		for (const IoHash& ChunkHash : DeletedEntries)
-		{
-			const DiskLocation& Location = Index[ChunkHash].Location;
-			ZEN_ASSERT(!Location.IsFlagSet(DiskLocation::kStandaloneFile));
-			DeletedSize += Index[ChunkHash].Location.GetBlockLocation(m_PayloadAlignment).Size;
-		}
-		DeletedCount += DeletedEntries.size();
-	};
-
-	// Move all chunks in blocks that have chunks removed to new blocks
-
-	Ref<BlockStoreFile> NewBlockFile;
-	uint64_t			WriteOffset	  = 0;
-	uint32_t			NewBlockIndex = 0;
-
-	auto UpdateLocations = [this](const std::span<DiskIndexEntry>& Entries) {
-		for (const DiskIndexEntry& Entry : Entries)
-		{
-			if (Entry.Location.IsFlagSet(DiskLocation::kTombStone))
+	std::vector<IoHash> DeletedChunks;
+	m_BlockStore.ReclaimSpace(
+		BlockStoreState,
+		ChunkLocations,
+		KeepChunkIndexes,
+		m_PayloadAlignment,
+		false,
+		[this, &DeletedChunks, &ChunkIndexToChunkHash, &Index, &ReadBlockTimeUs, &ReadBlockLongestTimeUs](
+			uint32_t,
+			const std::unordered_map<size_t, BlockStoreLocation>& MovedChunks,
+			const std::vector<size_t>&							  RemovedChunks) {
+			std::vector<DiskIndexEntry> LogEntries;
+			LogEntries.reserve(MovedChunks.size() + RemovedChunks.size());
+			for (const auto& Entry : MovedChunks)
 			{
-				auto	 KeyIt	   = m_Index.find(Entry.Key);
-				uint64_t ChunkSize = KeyIt->second.Location.GetBlockLocation(m_PayloadAlignment).Size;
-				m_TotalSize.fetch_sub(ChunkSize, std::memory_order_seq_cst);
-				m_Index.erase(KeyIt);
-				continue;
+				size_t					  ChunkIndex	  = Entry.first;
+				const BlockStoreLocation& NewLocation	  = Entry.second;
+				const IoHash&			  ChunkHash		  = ChunkIndexToChunkHash[ChunkIndex];
+				const DiskLocation&		  OldDiskLocation = Index[ChunkHash].Location;
+				LogEntries.push_back(
+					{.Key = ChunkHash, .Location = DiskLocation(NewLocation, m_PayloadAlignment, OldDiskLocation.GetFlags())});
+			}
+			for (const size_t ChunkIndex : RemovedChunks)
+			{
+				const IoHash&		ChunkHash		= ChunkIndexToChunkHash[ChunkIndex];
+				const DiskLocation& OldDiskLocation = Index[ChunkHash].Location;
+				LogEntries.push_back({.Key		= ChunkHash,
+									  .Location = DiskLocation(OldDiskLocation.GetBlockLocation(m_PayloadAlignment),
+															   m_PayloadAlignment,
+															   OldDiskLocation.GetFlags() | DiskLocation::kTombStone)});
+				DeletedChunks.push_back(ChunkHash);
 			}
-			m_Index[Entry.Key].Location = Entry.Location;
-		}
-	};
-
-	std::unordered_map<IoHash, DiskLocation> MovedBlockChunks;
-	for (uint32_t BlockIndex : BlocksToReWrite)
-	{
-		const size_t ChunkMapIndex = BlockIndexToChunkMapIndex[BlockIndex];
-
-		Ref<BlockStoreFile> OldBlockFile;
-		{
-			RwLock::SharedLockScope _i(m_IndexLock);
-			OldBlockFile = m_ChunkBlocks[BlockIndex];
-		}
 
-		const std::vector<IoHash>& KeepMap = KeepChunks[ChunkMapIndex];
-		if (KeepMap.empty())
-		{
-			const std::vector<IoHash>&	DeleteMap  = DeleteChunks[ChunkMapIndex];
-			std::vector<DiskIndexEntry> LogEntries = MakeDiskIndexEntries({}, DeleteMap);
 			m_SlogFile.Append(LogEntries);
 			m_SlogFile.Flush();
 			{
-				RwLock::ExclusiveLockScope _i(m_IndexLock);
+				RwLock::ExclusiveLockScope __(m_IndexLock);
 				Stopwatch				   Timer;
-				const auto				   __ = MakeGuard([&Timer, &ReadBlockTimeUs, &ReadBlockLongestTimeUs] {
+				const auto				   ____ = MakeGuard([&Timer, &ReadBlockTimeUs, &ReadBlockLongestTimeUs] {
 					uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
 					ReadBlockTimeUs += ElapsedUs;
 					ReadBlockLongestTimeUs = std::max(ElapsedUs, ReadBlockLongestTimeUs);
 				});
-				UpdateLocations(LogEntries);
-				m_ChunkBlocks[BlockIndex] = nullptr;
-			}
-			AddToDeleted(DeleteMap);
-			ZEN_DEBUG("marking cas store file for delete '{}', block #{}, '{}'",
-					  m_BucketDir / m_BucketName,
-					  BlockIndex,
-					  OldBlockFile->GetPath());
-			std::error_code Ec;
-			OldBlockFile->MarkAsDeleteOnClose(Ec);
-			if (Ec)
-			{
-				ZEN_WARN("Failed to flag file '{}' for deletion, reason: '{}'", OldBlockFile->GetPath(), Ec.message());
-			}
-			continue;
-		}
-
-		std::vector<uint8_t> Chunk;
-		for (const IoHash& ChunkHash : KeepMap)
-		{
-			auto					 KeyIt		   = Index.find(ChunkHash);
-			const BlockStoreLocation ChunkLocation = KeyIt->second.Location.GetBlockLocation(m_PayloadAlignment);
-			Chunk.resize(ChunkLocation.Size);
-			OldBlockFile->Read(Chunk.data(), Chunk.size(), ChunkLocation.Offset);
-
-			if (!NewBlockFile || (WriteOffset + Chunk.size() > MaxBlockSize))
-			{
-				uint32_t					NextBlockIndex = m_WriteBlockIndex.load(std::memory_order_relaxed);
-				std::vector<DiskIndexEntry> LogEntries	   = MakeDiskIndexEntries(MovedBlockChunks, {});
-				m_SlogFile.Append(LogEntries);
-				m_SlogFile.Flush();
-
-				if (NewBlockFile)
-				{
-					NewBlockFile->Truncate(WriteOffset);
-					NewBlockFile->Flush();
-				}
+				for (const DiskIndexEntry& Entry : LogEntries)
 				{
-					RwLock::ExclusiveLockScope __(m_IndexLock);
-					Stopwatch				   Timer;
-					const auto				   ___ = MakeGuard([&Timer, &ReadBlockTimeUs, &ReadBlockLongestTimeUs] {
-						uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
-						ReadBlockTimeUs += ElapsedUs;
-						ReadBlockLongestTimeUs = std::max(ElapsedUs, ReadBlockLongestTimeUs);
-					});
-					UpdateLocations(LogEntries);
-					if (m_ChunkBlocks.size() == BlockStoreDiskLocation::MaxBlockIndex)
+					if (Entry.Location.GetFlags() & DiskLocation::kTombStone)
 					{
-						ZEN_ERROR("unable to allocate a new block in '{}', count limit {} exeeded",
-								  m_BucketDir / m_BucketName,
-								  static_cast<uint64_t>(std::numeric_limits<uint32_t>::max()) + 1);
-						return;
-					}
-					while (m_ChunkBlocks.contains(NextBlockIndex))
-					{
-						NextBlockIndex = (NextBlockIndex + 1) & BlockStoreDiskLocation::MaxBlockIndex;
-					}
-					std::filesystem::path NewBlockPath = GetBlockPath(m_BlocksBasePath, NextBlockIndex);
-					NewBlockFile					   = new BlockStoreFile(NewBlockPath);
-					m_ChunkBlocks[NextBlockIndex]	   = NewBlockFile;
-				}
-
-				MovedCount += MovedBlockChunks.size();
-				MovedBlockChunks.clear();
-
-				std::error_code Error;
-				DiskSpace		Space = DiskSpaceInfo(m_BucketDir, Error);
-				if (Error)
-				{
-					ZEN_ERROR("get disk space in '{}' FAILED, reason: '{}'", m_BucketDir, Error.message());
-					return;
-				}
-				if (Space.Free < MaxBlockSize)
-				{
-					uint64_t ReclaimedSpace = GcCtx.ClaimGCReserve();
-					if (Space.Free + ReclaimedSpace < MaxBlockSize)
-					{
-						ZEN_WARN("garbage collect from '{}' FAILED, required disk space {}, free {}",
-								 m_BucketDir / m_BucketName,
-								 MaxBlockSize,
-								 NiceBytes(Space.Free + ReclaimedSpace));
-						RwLock::ExclusiveLockScope _l(m_IndexLock);
-						Stopwatch				   Timer;
-						const auto				   __ = MakeGuard([&Timer, &ReadBlockTimeUs, &ReadBlockLongestTimeUs] {
-							uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
-							ReadBlockTimeUs += ElapsedUs;
-							ReadBlockLongestTimeUs = std::max(ElapsedUs, ReadBlockLongestTimeUs);
-						});
-						m_ChunkBlocks.erase(NextBlockIndex);
-						return;
+						m_Index.erase(Entry.Key);
+						uint64_t ChunkSize = Entry.Location.GetBlockLocation(m_PayloadAlignment).Size;
+						m_TotalSize.fetch_sub(ChunkSize);
+						continue;
 					}
-
-					ZEN_INFO("using gc reserve for '{}', reclaimed {}, disk free {}",
-							 m_BucketDir / m_BucketName,
-							 ReclaimedSpace,
-							 NiceBytes(Space.Free + ReclaimedSpace));
+					m_Index[Entry.Key].Location = Entry.Location;
 				}
-				NewBlockFile->Create(MaxBlockSize);
-				NewBlockIndex = NextBlockIndex;
-				WriteOffset	  = 0;
 			}
+		});
 
-			NewBlockFile->Write(Chunk.data(), Chunk.size(), WriteOffset);
-			MovedBlockChunks.emplace(ChunkHash,
-									 DiskLocation({.BlockIndex = NewBlockIndex, .Offset = WriteOffset, .Size = Chunk.size()},
-												  m_PayloadAlignment,
-												  KeyIt->second.Location.Flags));
-			WriteOffset = RoundUp(WriteOffset + Chunk.size(), m_PayloadAlignment);
-		}
-		Chunk.clear();
-		if (NewBlockFile)
-		{
-			NewBlockFile->Truncate(WriteOffset);
-			NewBlockFile->Flush();
-			NewBlockFile = {};
-		}
-
-		const std::vector<IoHash>&	DeleteMap  = DeleteChunks[ChunkMapIndex];
-		std::vector<DiskIndexEntry> LogEntries = MakeDiskIndexEntries(MovedBlockChunks, DeleteMap);
-		m_SlogFile.Append(LogEntries);
-		m_SlogFile.Flush();
-		{
-			RwLock::ExclusiveLockScope __(m_IndexLock);
-			Stopwatch				   Timer;
-			const auto				   ___ = MakeGuard([&Timer, &ReadBlockTimeUs, &ReadBlockLongestTimeUs] {
-				uint64_t ElapsedUs = Timer.GetElapsedTimeUs();
-				ReadBlockTimeUs += ElapsedUs;
-				ReadBlockLongestTimeUs = std::max(ElapsedUs, ReadBlockLongestTimeUs);
-			});
-			UpdateLocations(LogEntries);
-			m_ChunkBlocks[BlockIndex] = nullptr;
-		}
-		MovedCount += MovedBlockChunks.size();
-		AddToDeleted(DeleteMap);
-		MovedBlockChunks.clear();
-
-		ZEN_DEBUG("marking cas store file for delete '{}', block #{}, '{}'",
-				  m_BucketDir / m_BucketName,
-				  BlockIndex,
-				  OldBlockFile->GetPath());
-		std::error_code Ec;
-		OldBlockFile->MarkAsDeleteOnClose(Ec);
-		if (Ec)
-		{
-			ZEN_WARN("Failed to flag file '{}' for deletion: '{}'", OldBlockFile->GetPath(), Ec.message());
-		}
-		OldBlockFile = nullptr;
-	}
+	GcCtx.DeletedCas(DeletedChunks);
 }
 
 void
@@ -2367,6 +2020,47 @@ ZenCacheDiskLayer::CacheBucket::PutStandaloneCacheValue(const IoHash& HashKey, c
 	m_TotalSize.fetch_add(Loc.Size(), std::memory_order_seq_cst);
 }
 
+void
+ZenCacheDiskLayer::CacheBucket::PutInlineCacheValue(const IoHash& HashKey, const ZenCacheValue& Value)
+{
+	uint8_t EntryFlags = 0;
+
+	if (Value.Value.GetContentType() == ZenContentType::kCbObject)
+	{
+		EntryFlags |= DiskLocation::kStructured;
+	}
+	else if (Value.Value.GetContentType() == ZenContentType::kCompressedBinary)
+	{
+		EntryFlags |= DiskLocation::kCompressed;
+	}
+
+	uint64_t ChunkSize = Value.Value.Size();
+
+	m_BlockStore.WriteChunk(Value.Value.Data(),
+							ChunkSize,
+							m_PayloadAlignment,
+							[this, &HashKey, EntryFlags](const BlockStoreLocation& BlockStoreLocation) {
+								DiskLocation		 Location(BlockStoreLocation, m_PayloadAlignment, EntryFlags);
+								const DiskIndexEntry DiskIndexEntry{.Key = HashKey, .Location = Location};
+								m_SlogFile.Append(DiskIndexEntry);
+								m_TotalSize.fetch_add(BlockStoreLocation.Size, std::memory_order_seq_cst);
+								RwLock::ExclusiveLockScope __(m_IndexLock);
+								if (auto It = m_Index.find(HashKey); It != m_Index.end())
+								{
+									// TODO: should check if write is idempotent and bail out if it is?
+									// this would requiring comparing contents on disk unless we add a
+									// content hash to the index entry
+									IndexEntry& Entry = It.value();
+									Entry.Location	  = Location;
+									Entry.LastAccess.store(GcClock::TickCount(), std::memory_order_relaxed);
+								}
+								else
+								{
+									m_Index.insert({HashKey, {Location, GcClock::TickCount()}});
+								}
+							});
+}
+
 //////////////////////////////////////////////////////////////////////////
 
 ZenCacheDiskLayer::ZenCacheDiskLayer(const std::filesystem::path& RootDir) : m_RootDir(RootDir)
@@ -3026,7 +2720,7 @@ TEST_CASE("z$.legacyconversion")
 	std::filesystem::path BucketDir		= TempDir.Path() / Bucket;
 	std::filesystem::path BlocksBaseDir = BucketDir / "blocks";
 
-	std::filesystem::path CasPath		 = GetBlockPath(BlocksBaseDir, 1);
+	std::filesystem::path CasPath		 = BlockStore ::GetBlockPath(BlocksBaseDir, 1);
 	std::filesystem::path LegacyDataPath = GetLegacyDataPath(BucketDir);
 	std::filesystem::remove(LegacyDataPath);
 	std::filesystem::rename(CasPath, LegacyDataPath);
diff --git a/zenserver/cache/structuredcachestore.h b/zenserver/cache/structuredcachestore.h
index c107983b5..0c2a7c0b2 100644
--- a/zenserver/cache/structuredcachestore.h
+++ b/zenserver/cache/structuredcachestore.h
@@ -255,6 +255,7 @@ private:
 		std::string			  m_BucketName;
 		std::filesystem::path m_BucketDir;
 		std::filesystem::path m_BlocksBasePath;
+		BlockStore			  m_BlockStore;
 		Oid					  m_BucketId;
 		bool				  m_IsOk				 = false;
 		uint64_t			  m_LargeObjectThreshold = 64 * 1024;
@@ -286,20 +287,15 @@ private:
 
 		using IndexMap = tsl::robin_map<IoHash, IndexEntry, IoHash::Hasher>;
 
-		RwLock											  m_IndexLock;
-		IndexMap										  m_Index;
-		std::unordered_map<uint32_t, Ref<BlockStoreFile>> m_ChunkBlocks;
+		RwLock	 m_IndexLock;
+		IndexMap m_Index;
 
-		RwLock				m_InsertLock;  // used to serialize inserts
-		Ref<BlockStoreFile> m_WriteBlock;
-		std::uint64_t		m_CurrentInsertOffset = 0;
-
-		std::atomic_uint32_t m_WriteBlockIndex{};
 		std::atomic_uint64_t m_TotalSize{};
 
 		void	 BuildPath(PathBuilderBase& Path, const IoHash& HashKey);
 		void	 PutStandaloneCacheValue(const IoHash& HashKey, const ZenCacheValue& Value);
 		bool	 GetStandaloneCacheValue(const DiskLocation& Loc, const IoHash& HashKey, ZenCacheValue& OutValue);
+		void	 PutInlineCacheValue(const IoHash& HashKey, const ZenCacheValue& Value);
 		bool	 GetInlineCacheValue(const DiskLocation& Loc, ZenCacheValue& OutValue);
 		void	 MakeIndexSnapshot();
 		uint64_t ReadIndexFile();
diff --git a/zenstore/blockstore.cpp b/zenstore/blockstore.cpp
index 4cf3c6486..309c99d1e 100644
--- a/zenstore/blockstore.cpp
+++ b/zenstore/blockstore.cpp
@@ -1,11 +1,11 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
-#include "compactcas.h"
+#include <zenstore/blockstore.h>
 
 #include <zencore/fmtutils.h>
 #include <zencore/logging.h>
 #include <zencore/scopeguard.h>
-#include <zenstore/blockstore.h>
+#include <zencore/timer.h>
 
 #if ZEN_WITH_TESTS
 #	include <zencore/compactbinarybuilder.h>
@@ -111,26 +111,6 @@ BlockStoreFile::StreamByteRange(uint64_t FileOffset, uint64_t Size, std::functio
 	m_File.StreamByteRange(FileOffset, Size, std::move(ChunkFun));
 }
 
-namespace {
-	const char* DataExtension = ".ucas";
-
-	std::filesystem::path GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint32_t BlockIndex)
-	{
-		ExtendablePathBuilder<256> Path;
-
-		char BlockHexString[9];
-		ToHexNumber(BlockIndex, BlockHexString);
-
-		Path.Append(BlocksBasePath);
-		Path.AppendSeparator();
-		Path.AppendAsciiRange(BlockHexString, BlockHexString + 4);
-		Path.AppendSeparator();
-		Path.Append(BlockHexString);
-		Path.Append(DataExtension);
-		return Path.ToPath();
-	}
-}  // namespace
-
 void
 BlockStore::Initialize(const std::filesystem::path&			  BlocksBasePath,
 					   uint64_t								  MaxBlockSize,
@@ -171,7 +151,7 @@ BlockStore::Initialize(const std::filesystem::path&			  BlocksBasePath,
 				if (Entry.is_regular_file())
 				{
 					const std::filesystem::path Path = Entry.path();
-					if (Path.extension() != DataExtension)
+					if (Path.extension() != GetBlockFileExtension())
 					{
 						continue;
 					}
@@ -595,6 +575,29 @@ BlockStore::ReclaimSpace(const ReclaimSnapshotState&			Snapshot,
 	return;
 }
 
+const char*
+BlockStore::GetBlockFileExtension()
+{
+	return ".ucas";
+}
+
+std::filesystem::path
+BlockStore::GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint32_t BlockIndex)
+{
+	ExtendablePathBuilder<256> Path;
+
+	char BlockHexString[9];
+	ToHexNumber(BlockIndex, BlockHexString);
+
+	Path.Append(BlocksBasePath);
+	Path.AppendSeparator();
+	Path.AppendAsciiRange(BlockHexString, BlockHexString + 4);
+	Path.AppendSeparator();
+	Path.Append(BlockHexString);
+	Path.Append(GetBlockFileExtension());
+	return Path.ToPath();
+}
+
 #if ZEN_WITH_TESTS
 
 static bool
diff --git a/zenstore/compactcas.cpp b/zenstore/compactcas.cpp
index 84019d7aa..30747f554 100644
--- a/zenstore/compactcas.cpp
+++ b/zenstore/compactcas.cpp
@@ -66,7 +66,6 @@ namespace {
 
 	const char* IndexExtension = ".uidx";
 	const char* LogExtension   = ".ulog";
-	const char* DataExtension  = ".ucas";
 
 	std::filesystem::path GetBasePath(const std::filesystem::path& RootPath, const std::string& ContainerBaseName)
 	{
@@ -93,22 +92,6 @@ namespace {
 		return GetBasePath(RootPath, ContainerBaseName) / "blocks";
 	}
 
-	std::filesystem::path GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint32_t BlockIndex)
-	{
-		ExtendablePathBuilder<256> Path;
-
-		char BlockHexString[9];
-		ToHexNumber(BlockIndex, BlockHexString);
-
-		Path.Append(BlocksBasePath);
-		Path.AppendSeparator();
-		Path.AppendAsciiRange(BlockHexString, BlockHexString + 4);
-		Path.AppendSeparator();
-		Path.Append(BlockHexString);
-		Path.Append(DataExtension);
-		return Path.ToPath();
-	}
-
 	std::filesystem::path GetLegacyLogPath(const std::filesystem::path& RootPath, const std::string& ContainerBaseName)
 	{
 		return RootPath / (ContainerBaseName + LogExtension);
@@ -116,7 +99,7 @@ namespace {
 
 	std::filesystem::path GetLegacyDataPath(const std::filesystem::path& RootPath, const std::string& ContainerBaseName)
 	{
-		return RootPath / (ContainerBaseName + DataExtension);
+		return RootPath / (ContainerBaseName + ".ucas");
 	}
 
 	std::filesystem::path GetLegacyIndexPath(const std::filesystem::path& RootPath, const std::string& ContainerBaseName)
@@ -315,7 +298,7 @@ CasContainerStrategy::FindChunk(const IoHash& ChunkHash)
 	BlockStoreLocation Location = KeyIt->second.Get(m_PayloadAlignment);
 	_.ReleaseNow();
 
-	Ref<BlockStoreFile> ChunkBlock = m_BlockStore.GetChunkBlock(Location);	// m_ChunkBlocks[Location.BlockIndex];
+	Ref<BlockStoreFile> ChunkBlock = m_BlockStore.GetChunkBlock(Location);
 	if (!ChunkBlock)
 	{
 		return IoBuffer();
@@ -348,17 +331,6 @@ void
 CasContainerStrategy::Flush()
 {
 	m_BlockStore.Flush();
-	/* {
-		RwLock::ExclusiveLockScope _(m_InsertLock);
-		if (m_CurrentInsertOffset > 0)
-		{
-			uint32_t WriteBlockIndex = m_WriteBlockIndex.load(std::memory_order_acquire);
-			WriteBlockIndex			 = (WriteBlockIndex + 1) & BlockStoreDiskLocation::MaxBlockIndex;
-			m_WriteBlock			 = nullptr;
-			m_WriteBlockIndex.store(WriteBlockIndex, std::memory_order_release);
-			m_CurrentInsertOffset = 0;
-		}
-	}*/
 	MakeIndexSnapshot();
 }
 
@@ -533,8 +505,6 @@ CasContainerStrategy::CollectGarbage(GcContext& GcCtx)
 		return;
 	}
 
-	auto GetChunkLocations = [] {};
-
 	std::vector<IoHash> DeletedChunks;
 	m_BlockStore.ReclaimSpace(
 		BlockStoreState,
@@ -543,7 +513,7 @@ CasContainerStrategy::CollectGarbage(GcContext& GcCtx)
 		m_PayloadAlignment,
 		false,
 		[this, &DeletedChunks, &ChunkIndexToChunkHash, &LocationMap, &ReadBlockTimeUs, &ReadBlockLongestTimeUs](
-			uint32_t											  BlockIndex,
+			uint32_t,
 			const std::unordered_map<size_t, BlockStoreLocation>& MovedChunks,
 			const std::vector<size_t>&							  RemovedChunks) {
 			std::vector<CasDiskIndexEntry> LogEntries;
@@ -578,17 +548,12 @@ CasContainerStrategy::CollectGarbage(GcContext& GcCtx)
 					if (Entry.Flags & CasDiskIndexEntry::kTombstone)
 					{
 						m_LocationMap.erase(Entry.Key);
-						auto	 KeyIt	   = m_LocationMap.find(Entry.Key);
 						uint64_t ChunkSize = Entry.Location.GetSize();
 						m_TotalSize.fetch_sub(ChunkSize);
 						continue;
 					}
 					m_LocationMap[Entry.Key] = Entry.Location;
 				}
-				for (const auto& Entry : m_LocationMap)
-				{
-					ZEN_ASSERT(Entry.second.GetBlockIndex() != BlockIndex);
-				}
 			}
 		});
 
@@ -809,7 +774,7 @@ CasContainerStrategy::MigrateLegacyData(bool CleanSource)
 	});
 
 	uint32_t WriteBlockIndex = 0;
-	while (std::filesystem::exists(GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
+	while (std::filesystem::exists(BlockStore::GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
 	{
 		++WriteBlockIndex;
 	}
@@ -976,7 +941,7 @@ CasContainerStrategy::MigrateLegacyData(bool CleanSource)
 			LogEntries.push_back(
 				{.Key = Entry.second.Key, .Location = NewLocation, .ContentType = Record.ContentType, .Flags = Record.Flags});
 		}
-		std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, WriteBlockIndex);
+		std::filesystem::path BlockPath = BlockStore::GetBlockPath(m_BlocksBasePath, WriteBlockIndex);
 		CreateDirectories(BlockPath.parent_path());
 		BlockFile.Close();
 		std::filesystem::rename(LegacyDataPath, BlockPath);
@@ -1038,7 +1003,7 @@ CasContainerStrategy::MigrateLegacyData(bool CleanSource)
 				BlockRanges.push_back(BlockRange);
 
 				WriteBlockIndex++;
-				while (std::filesystem::exists(GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
+				while (std::filesystem::exists(BlockStore::GetBlockPath(m_BlocksBasePath, WriteBlockIndex)))
 				{
 					++WriteBlockIndex;
 				}
@@ -1077,7 +1042,7 @@ CasContainerStrategy::MigrateLegacyData(bool CleanSource)
 						 NiceTimeSpanMs(ETA));
 			}
 
-			std::filesystem::path BlockPath = GetBlockPath(m_BlocksBasePath, BlockRange.BlockIndex);
+			std::filesystem::path BlockPath = BlockStore::GetBlockPath(m_BlocksBasePath, BlockRange.BlockIndex);
 			BlockStoreFile		  ChunkBlock(BlockPath);
 			ChunkBlock.Create(BlockRange.BlockSize);
 			uint64_t Offset = 0;
@@ -1176,14 +1141,12 @@ CasContainerStrategy::OpenContainer(bool IsNewStore)
 	std::filesystem::path LogPath = GetLogPath(m_Config.RootDirectory, m_ContainerBaseName);
 	m_CasLog.Open(LogPath, CasLogFile::Mode::kWrite);
 
-	std::unordered_set<uint32_t>	KnownBlocks;
 	std::vector<BlockStoreLocation> KnownLocations;
 	KnownLocations.reserve(m_LocationMap.size());
 	for (const auto& Entry : m_LocationMap)
 	{
 		const BlockStoreDiskLocation& Location = Entry.second;
 		m_TotalSize.fetch_add(Location.GetSize(), std::memory_order_seq_cst);
-		KnownBlocks.insert(Location.GetBlockIndex());
 		KnownLocations.push_back(Location.Get(m_PayloadAlignment));
 	}
 
@@ -1842,7 +1805,7 @@ TEST_CASE("compactcas.legacyconversion")
 		Gc.CollectGarbage(GcCtx);
 	}
 
-	std::filesystem::path BlockPath		 = GetBlockPath(GetBlocksBasePath(CasConfig.RootDirectory, "test"), 1);
+	std::filesystem::path BlockPath		 = BlockStore::GetBlockPath(GetBlocksBasePath(CasConfig.RootDirectory, "test"), 1);
 	std::filesystem::path LegacyDataPath = GetLegacyDataPath(CasConfig.RootDirectory, "test");
 	std::filesystem::rename(BlockPath, LegacyDataPath);
 
diff --git a/zenstore/include/zenstore/blockstore.h b/zenstore/include/zenstore/blockstore.h
index 084142636..1eff46367 100644
--- a/zenstore/include/zenstore/blockstore.h
+++ b/zenstore/include/zenstore/blockstore.h
@@ -143,6 +143,9 @@ public:
 						const ReclaimCallback& Callback = [](uint32_t, const std::unordered_map<size_t, BlockStoreLocation>&, const std::vector<size_t>&) {
 		});
 
+	static const char*			 GetBlockFileExtension();
+	static std::filesystem::path GetBlockPath(const std::filesystem::path& BlocksBasePath, const uint32_t BlockIndex);
+
 private:
 	std::unordered_map<uint32_t, Ref<BlockStoreFile>> m_ChunkBlocks;