Use bitpacking for Cas block location

1 files changed, 26 insertions, 37 deletions

diff --git a/zenstore/compactcas.h b/zenstore/compactcas.h
index 5f58ccab1..91c7c6981 100644
--- a/zenstore/compactcas.h
+++ b/zenstore/compactcas.h
@@ -19,16 +19,35 @@ namespace zen {
 
 //////////////////////////////////////////////////////////////////////////
 
+struct CasLocation
+{
+	uint32_t BlockIndex;
+	uint64_t Offset;
+	uint64_t Size;
+};
+
 #pragma pack(push)
 #pragma pack(1)
 
 struct CasDiskLocation
 {
-	// 20 bits blockindex
-	// 28 bits offset
-	// 32 bits size
+	constexpr static uint32_t MaxBlockIndexBits = 20;
+	constexpr static uint32_t MaxOffsetBits		= 28;
+	constexpr static uint32_t MaxBlockIndex		= (1ul << CasDiskLocation::MaxBlockIndexBits) - 1ul;
+	constexpr static uint32_t MaxOffset			= (1ul << CasDiskLocation::MaxOffsetBits) - 1ul;
+
+	explicit CasDiskLocation(const CasLocation& Location) { Init(Location.BlockIndex, Location.Offset, Location.Size); }
+
+	CasDiskLocation() = default;
 
-	CasDiskLocation(uint32_t BlockIndex, uint64_t Offset, uint64_t Size)
+	inline CasLocation operator*() const { return {.BlockIndex = BlockIndex(), .Offset = Offset(), .Size = Size()}; }
+
+private:
+	inline uint32_t BlockIndex() const { return (static_cast<uint32_t>(m_BlockIndexAndOffsetHighBits & 0xf) << 16) | m_BlockIndexLowBits; }
+	inline uint64_t Offset() const { return (static_cast<uint64_t>(m_BlockIndexAndOffsetHighBits & 0xfff0) << 12) | m_OffsetLowBits; }
+	inline uint64_t Size() const { return m_Size; }
+
+	inline void Init(uint32_t BlockIndex, uint64_t Offset, uint64_t Size)
 	{
 		ZEN_ASSERT(BlockIndex < (1L << 20));
 		ZEN_ASSERT(Offset < (1L << 28));
@@ -40,40 +59,10 @@ struct CasDiskLocation
 		m_BlockIndexAndOffsetHighBits = static_cast<uint16_t>(((BlockIndex >> 16) & 0xf) | (((Offset >> 16) & 0xfff) << 4));
 	}
 
-	CasDiskLocation() = default;
-
-	inline uint32_t GetBlockIndex() const
-	{
-		return (static_cast<uint32_t>(m_BlockIndexAndOffsetHighBits & 0xf) << 16) | m_BlockIndexLowBits;
-	}
-	inline uint64_t Offset() const { return (static_cast<uint64_t>(m_BlockIndexAndOffsetHighBits & 0xfff0) << 8) | m_OffsetLowBits; }
-	inline uint64_t Size() const { return m_Size; }
-
-private:
 	uint32_t m_Size;
 	uint16_t m_BlockIndexLowBits;
 	uint16_t m_OffsetLowBits;
 	uint16_t m_BlockIndexAndOffsetHighBits;
-
-#if 0
-	// 24 bits blockindex
-	// 24 bits offset
-	// 32 bits size
-	inline uint32_t GetBlockIndex() const
-	{
-		return (static_cast<uint32_t>(BlockIndexHighBits) << 16) | BlockIndexLowBits;
-	}
-	inline uint32_t Offset() const
-	{ 
-		return (static_cast<uint32_t>(OffsetHighBits) << 16) | OffsetLowBits;
-	}
-
-	uint32_t Size;
-	uint16_t BlockIndexLowBits;
-	uint16_t OffsetLowBits;
-	uint8_t	 BlockIndexHighBits;
-	uint8_t	 OffsetHighBits;
-#endif
 };
 
 struct CasDiskIndexEntry
@@ -134,10 +123,10 @@ private:
 	std::unordered_map<IoHash, CasDiskLocation, IoHash::Hasher> m_LocationMap;
 
 	RwLock													  m_InsertLock;	 // used to serialize inserts
-	std::unordered_map<uint16_t, std::shared_ptr<ChunkBlock>> m_OpenBlocks;
+	std::unordered_map<uint32_t, std::shared_ptr<ChunkBlock>> m_OpenBlocks;
 	std::weak_ptr<ChunkBlock>								  m_CurrentBlock;
-	uint16_t												  m_CurrentBlockIndex = 0;
-	std::atomic_uint32_t									  m_CurrentInsertOffset{};
+	uint32_t												  m_CurrentBlockIndex = 0;
+	std::atomic_uint64_t									  m_CurrentInsertOffset{};
 	std::atomic_uint64_t									  m_TotalSize{};
 
 	void MakeIndexSnapshot();