batch fetch record cache values (#266)

- Improvement: Batch fetch record attachments when appropriate
- Improvement: Reduce memory buffer allocation in BlockStore::IterateBlock
- Improvement: Tweaked BlockStore::IterateBlock logic when to use threaded work (at least 4 chunks requested)
- Bugfix: CasContainerStrategy::IterateChunks could give wrong payload/index when requesting 1 or 2 chunks

1 files changed, 7 insertions, 2 deletions

diff --git a/src/zenstore/blockstore.cpp b/src/zenstore/blockstore.cpp
index 9ad672060..3974fb989 100644
--- a/src/zenstore/blockstore.cpp
+++ b/src/zenstore/blockstore.cpp
@@ -809,8 +809,8 @@ BlockStore::IterateBlock(std::span<const BlockStoreLocation>   ChunkLocations,
 		ZEN_ASSERT(BlockFile);
 		InsertLock.ReleaseNow();
 
-		IoBuffer ReadBuffer{IterateSmallChunkWindowSize};
-		void*	 BufferBase = ReadBuffer.MutableData();
+		IoBuffer ReadBuffer;
+		void*	 BufferBase = nullptr;
 
 		size_t LocationIndexOffset = 0;
 		while (LocationIndexOffset < ChunkIndexes.size())
@@ -825,6 +825,11 @@ BlockStore::IterateBlock(std::span<const BlockStoreLocation>   ChunkLocations,
 				size_t					  LastChunkIndex = ChunkIndexes[LocationIndexOffset + RangeCount - 1];
 				const BlockStoreLocation& LastLocation	 = ChunkLocations[LastChunkIndex];
 				uint64_t				  Size			 = LastLocation.Offset + LastLocation.Size - FirstLocation.Offset;
+				if (ReadBuffer.GetSize() < Size)
+				{
+					ReadBuffer = IoBuffer(Min(Size * 2, IterateSmallChunkWindowSize));
+					BufferBase = ReadBuffer.MutableData();
+				}
 				BlockFile->Read(BufferBase, Size, FirstLocation.Offset);
 				for (size_t RangeIndex = 0; RangeIndex < RangeCount; ++RangeIndex)
 				{