store

Documentation

Index

• func IsKeyNotFound(err error) bool
• type Engine
  • func NewEngine(dir string) (Engine, error)
• type KVTxn
• type MergeFunc
• type Snapshot

Functions

func IsKeyNotFound

func IsKeyNotFound(err error) bool

Types

type Engine

type Engine interface {
	// Name engine name
	Name() string

	// Txn read-write transaction
	Txn(fn func(KVTxn) error) error

	// View read-only transaction
	View(fn func(KVTxn) error) error

	// Update read-write transaction
	Update(fn func(KVTxn) error) error

	// Snapshot return a mvcc snapshot
	Snapshot() (Snapshot, error)

	// Close engine
	Close() error
}

Engine support txn

func NewEngine

func NewEngine(dir string) (Engine, error)

NewEngine creates a new txn engine

type KVTxn

type KVTxn interface {
	Get(key []byte) ([]byte, error)
	Gets(keys ...[]byte) ([][]byte, error)
	Set(key, value []byte) error
	Delete(key []byte) error
	Deletes(keys ...[]byte) error
	Incr(key []byte, value uint64) (uint64, error)
	Append(key, value []byte) ([]byte, error)
	Exist(key []byte) (bool, error)
	Add(key, value []byte) error
	Merge(key []byte, fn MergeFunc) ([]byte, error)
	ScanRange(begin, end []byte) (map[string][]byte, error)
	ScanKeys(prefix []byte, limit int) ([][]byte, error)
	ScanValues(prefix []byte, limit int) (map[string][]byte, error)
}

KVTxn for store

type MergeFunc

type MergeFunc func(existingVal, newVal []byte) []byte

MergeFunc accepts two byte slices, one representing an existing value, and another representing a new value that needs to be ‘merged’ into it. MergeFunc contains the logic to perform the ‘merge’ and return an updated value. MergeFunc could perform operations like integer addition, list appends etc. Note that the ordering of the operands is maintained.

type Snapshot

type Snapshot interface {
	Name() string
	Get(key []byte) ([]byte, error)
	ScanRange(begin, end []byte) (map[string][]byte, error)
	ScanKeys(prefix []byte, limit int) ([][]byte, error)
	Close() error
}

Snapshot mvcc snapshot