writecache

Documentation

Overview

Package writecache implements write-cache for objects.

Write-cache uses file system tree for storing objects.

Flushing from the writecache to the main storage is done in the background.

Index

• Variables
• type Cache
  • func New(opts ...Option) Cache
• type Info
• type Metabase
• type ObjectStatus
• type Option
  • func WithBlobstor(bs *blobstor.BlobStor) Option
  • func WithFlushWorkersCount(c int) Option
  • func WithLogger(log *zap.Logger) Option
  • func WithMaxCacheSize(sz uint64) Option
  • func WithMaxObjectSize(sz uint64) Option
  • func WithMetabase(db Metabase) Option
  • func WithNoSync(noSync bool) Option
  • func WithPath(path string) Option
  • func WithReportErrorFunc(f func(string, error)) Option

Variables

var (
	// ErrBigObject is returned when object is too big to be placed in cache.
	ErrBigObject = errors.New("too big object")
	// ErrOutOfSpace is returned when there is no space left to put a new object.
	ErrOutOfSpace = errors.New("no space left in the write cache")
)

var ErrReadOnly = logicerr.New("write-cache is in read-only mode")

ErrReadOnly is returned when Put/Write is performed in a read-only mode.

Types

type Cache

type Cache interface {
	Get(address oid.Address) (*object.Object, error)
	// GetBytes reads object from the Cache by address into memory buffer in a
	// canonical NeoFS binary format. Returns [apistatus.ObjectNotFound] if object
	// is missing.
	GetBytes(oid.Address) ([]byte, error)
	Head(oid.Address) (*object.Object, error)
	// Delete removes object referenced by the given oid.Address from the
	// Cache. Returns any error encountered that prevented the object to be
	// removed.
	//
	// Returns apistatus.ObjectNotFound if object is missing in the Cache.
	// Returns ErrReadOnly if the Cache is currently in the read-only mode.
	Delete(oid.Address) error
	Iterate(func(oid.Address, []byte) error, bool) error
	Put(oid.Address, *object.Object, []byte) error
	SetMode(mode.Mode) error
	SetLogger(*zap.Logger)
	DumpInfo() Info
	Flush(bool) error

	Init() error
	Open(readOnly bool) error
	Close() error
	ObjectStatus(address oid.Address) (ObjectStatus, error)
}

Cache represents write-cache for objects.

func New

func New(opts ...Option) Cache

New creates new writecache instance.

type Info

type Info struct {
	// Full path to the write-cache.
	Path string
}

Info groups the information about write-cache.

type Metabase

type Metabase interface {
	Exists(addr oid.Address, ignoreExpiration bool) (bool, error)
	StorageID(addr oid.Address) ([]byte, error)
	UpdateStorageID(addr oid.Address, newID []byte) error
	Put(obj *objectSDK.Object, storageID []byte, binHeader []byte) error
}

Metabase is an interface to metabase sufficient for writecache to operate.

type ObjectStatus

type ObjectStatus struct {
	PathFSTree string
}

ObjectStatus represents the status of the object in the Writecache.

type Option

type Option func(*options)

Option represents write-cache configuration option.

func WithBlobstor

func WithBlobstor(bs *blobstor.BlobStor) Option

WithBlobstor sets main object storage.

func WithFlushWorkersCount

func WithFlushWorkersCount(c int) Option

WithFlushWorkersCount sets number of workers to flushing objects in parallel.

func WithLogger

func WithLogger(log *zap.Logger) Option

WithLogger sets logger.

func WithMaxCacheSize

func WithMaxCacheSize(sz uint64) Option

WithMaxCacheSize sets maximum write-cache size in bytes.

func WithMaxObjectSize

func WithMaxObjectSize(sz uint64) Option

WithMaxObjectSize sets maximum object size to be stored in write-cache.

func WithMetabase

func WithMetabase(db Metabase) Option

WithMetabase sets metabase.

func WithNoSync

func WithNoSync(noSync bool) Option

WithNoSync sets an option to allow returning to caller on PUT before write is persisted.

func WithPath

func WithPath(path string) Option

WithPath sets path to writecache db.

func WithReportErrorFunc

func WithReportErrorFunc(f func(string, error)) Option

WithReportErrorFunc sets error reporting function.