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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
#include "cacheshared.h"
#include <zencore/stats.h>
#include <zenstore/blockstore.h>
#include <zenstore/caslog.h>
ZEN_THIRD_PARTY_INCLUDES_START
#include <tsl/robin_map.h>
ZEN_THIRD_PARTY_INCLUDES_END
#include <filesystem>
namespace zen {
class IoBuffer;
#pragma pack(push)
#pragma pack(1)
struct DiskLocation
{
inline DiskLocation() = default;
inline DiskLocation(uint64_t ValueSize, uint8_t Flags) : Flags(Flags | kStandaloneFile) { Location.StandaloneSize = ValueSize; }
inline DiskLocation(const BlockStoreLocation& Location, uint64_t PayloadAlignment, uint8_t Flags) : Flags(Flags & ~kStandaloneFile)
{
this->Location.BlockLocation = BlockStoreDiskLocation(Location, PayloadAlignment);
}
inline BlockStoreLocation GetBlockLocation(uint64_t PayloadAlignment) const
{
ZEN_ASSERT(!(Flags & kStandaloneFile));
return Location.BlockLocation.Get(PayloadAlignment);
}
inline uint64_t Size() const { return (Flags & kStandaloneFile) ? Location.StandaloneSize : Location.BlockLocation.GetSize(); }
inline uint8_t IsFlagSet(uint64_t Flag) const { return Flags & Flag; }
inline uint8_t GetFlags() const { return Flags; }
inline ZenContentType GetContentType() const
{
ZenContentType ContentType = ZenContentType::kBinary;
if (IsFlagSet(kStructured))
{
ContentType = ZenContentType::kCbObject;
}
if (IsFlagSet(kCompressed))
{
ContentType = ZenContentType::kCompressedBinary;
}
return ContentType;
}
union
{
BlockStoreDiskLocation BlockLocation; // 10 bytes
uint64_t StandaloneSize = 0; // 8 bytes
} Location;
static const uint8_t kStandaloneFile = 0x80u; // Stored as a separate file
static const uint8_t kStructured = 0x40u; // Serialized as compact binary
static const uint8_t kTombStone = 0x20u; // Represents a deleted key/value
static const uint8_t kCompressed = 0x10u; // Stored in compressed buffer format
uint8_t Flags = 0;
uint8_t Reserved = 0;
};
struct DiskIndexEntry
{
IoHash Key; // 20 bytes
DiskLocation Location; // 12 bytes
};
#pragma pack(pop)
static_assert(sizeof(DiskIndexEntry) == 32);
//////////////////////////////////////////////////////////////////////////
class ZenCacheDiskLayer
{
public:
struct Configuration
{
std::filesystem::path RootDir;
};
struct BucketInfo
{
uint64_t EntryCount = 0;
uint64_t TotalSize = 0;
};
struct Info
{
Configuration Config;
std::vector<std::string> BucketNames;
uint64_t EntryCount = 0;
uint64_t TotalSize = 0;
};
struct BucketStats
{
uint64_t TotalSize;
uint64_t HitCount;
uint64_t MissCount;
uint64_t WriteCount;
metrics::RequestStatsSnapshot PutOps;
metrics::RequestStatsSnapshot GetOps;
};
struct NamedBucketStats
{
std::string BucketName;
BucketStats Stats;
};
struct DiskStats
{
std::vector<NamedBucketStats> BucketStats;
};
explicit ZenCacheDiskLayer(const std::filesystem::path& RootDir);
~ZenCacheDiskLayer();
bool Get(std::string_view Bucket, const IoHash& HashKey, ZenCacheValue& OutValue);
void Put(std::string_view Bucket, const IoHash& HashKey, const ZenCacheValue& Value);
bool Drop();
bool DropBucket(std::string_view Bucket);
void Flush();
void ScrubStorage(ScrubContext& Ctx);
void GatherReferences(GcContext& GcCtx);
void CollectGarbage(GcContext& GcCtx);
void UpdateAccessTimes(const zen::access_tracking::AccessTimes& AccessTimes);
void DiscoverBuckets();
uint64_t TotalSize() const;
DiskStats Stats() const;
Info GetInfo() const;
std::optional<BucketInfo> GetBucketInfo(std::string_view Bucket) const;
void EnumerateBucketContents(std::string_view Bucket,
std::function<void(const IoHash& Key, const CacheValueDetails::ValueDetails& Details)>& Fn) const;
CacheValueDetails::NamespaceDetails GetValueDetails(const std::string_view BucketFilter, const std::string_view ValueFilter) const;
private:
/** A cache bucket manages a single directory containing
metadata and data for that bucket
*/
struct CacheBucket
{
CacheBucket(std::string BucketName);
~CacheBucket();
bool OpenOrCreate(std::filesystem::path BucketDir, bool AllowCreate = true);
bool Get(const IoHash& HashKey, ZenCacheValue& OutValue);
void Put(const IoHash& HashKey, const ZenCacheValue& Value);
bool Drop();
void Flush();
void ScrubStorage(ScrubContext& Ctx);
void GatherReferences(GcContext& GcCtx);
void CollectGarbage(GcContext& GcCtx);
void UpdateAccessTimes(const std::vector<zen::access_tracking::KeyAccessTime>& AccessTimes);
inline uint64_t TotalSize() const { return m_TotalStandaloneSize.load(std::memory_order::relaxed) + m_BlockStore.TotalSize(); }
uint64_t EntryCount() const;
BucketStats Stats();
CacheValueDetails::BucketDetails GetValueDetails(const std::string_view ValueFilter) const;
void EnumerateBucketContents(std::function<void(const IoHash& Key, const CacheValueDetails::ValueDetails& Details)>& Fn) const;
private:
const uint64_t MaxBlockSize = 1ull << 30;
uint64_t m_PayloadAlignment = 1ull << 4;
std::string m_BucketName;
std::filesystem::path m_BucketDir;
std::filesystem::path m_BlocksBasePath;
BlockStore m_BlockStore;
Oid m_BucketId;
uint64_t m_LargeObjectThreshold = 128 * 1024;
// These files are used to manage storage of small objects for this bucket
TCasLogFile<DiskIndexEntry> m_SlogFile;
uint64_t m_LogFlushPosition = 0;
#pragma pack(push)
#pragma pack(1)
struct BucketPayload
{
DiskLocation Location; // 12
uint64_t RawSize; // 8
IoHash RawHash; // 20
};
#pragma pack(pop)
static_assert(sizeof(BucketPayload) == 40u);
static_assert(sizeof(AccessTime) == 4u);
using IndexMap = tsl::robin_map<IoHash, size_t, IoHash::Hasher>;
std::atomic<uint64_t> m_HitCount;
std::atomic<uint64_t> m_MissCount;
std::atomic<uint64_t> m_WriteCount;
metrics::RequestStats m_PutOps;
metrics::RequestStats m_GetOps;
mutable RwLock m_IndexLock;
std::vector<AccessTime> m_AccessTimes;
std::vector<BucketPayload> m_Payloads;
IndexMap m_Index;
std::atomic_uint64_t m_TotalStandaloneSize{};
void BuildPath(PathBuilderBase& Path, const IoHash& HashKey) const;
void PutStandaloneCacheValue(const IoHash& HashKey, const ZenCacheValue& Value);
IoBuffer GetStandaloneCacheValue(const DiskLocation& Loc, const IoHash& HashKey) const;
void PutInlineCacheValue(const IoHash& HashKey, const ZenCacheValue& Value);
IoBuffer GetInlineCacheValue(const DiskLocation& Loc) const;
void MakeIndexSnapshot();
uint64_t ReadIndexFile(const std::filesystem::path& IndexPath, uint32_t& OutVersion);
uint64_t ReadLog(const std::filesystem::path& LogPath, uint64_t LogPosition);
void OpenLog(const bool IsNew);
void SaveManifest();
CacheValueDetails::ValueDetails GetValueDetails(const IoHash& Key, size_t Index) const;
// These locks are here to avoid contention on file creation, therefore it's sufficient
// that we take the same lock for the same hash
//
// These locks are small and should really be spaced out so they don't share cache lines,
// but we don't currently access them at particularly high frequency so it should not be
// an issue in practice
mutable RwLock m_ShardedLocks[256];
inline RwLock& LockForHash(const IoHash& Hash) const { return m_ShardedLocks[Hash.Hash[19]]; }
};
std::filesystem::path m_RootDir;
mutable RwLock m_Lock;
std::unordered_map<std::string, std::unique_ptr<CacheBucket>> m_Buckets; // TODO: make this case insensitive
std::vector<std::unique_ptr<CacheBucket>> m_DroppedBuckets;
ZenCacheDiskLayer(const ZenCacheDiskLayer&) = delete;
ZenCacheDiskLayer& operator=(const ZenCacheDiskLayer&) = delete;
};
} // namespace zen
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