leveldb

Documentation

Overview

Package leveldb implements the key-value database layer based on LevelDB.

Index

• func NewProducer(datadir string, getCache func(string) int) kvdb.IterableDBProducer
• type Database
  • func New(path string, cache int, handles int, close func() error, drop func()) (*Database, error)
  • func (db *Database) Close() error
  • func (db *Database) Compact(start []byte, limit []byte) error
  • func (db *Database) Delete(key []byte) error
  • func (db *Database) Drop()
  • func (db *Database) Get(key []byte) ([]byte, error)
  • func (db *Database) GetSnapshot() (kvdb.Snapshot, error)
  • func (db *Database) Has(key []byte) (bool, error)
  • func (db *Database) NewBatch() kvdb.Batch
  • func (db *Database) NewIterator(prefix []byte, start []byte) kvdb.Iterator
  • func (db *Database) Path() string
  • func (db *Database) Put(key []byte, value []byte) error
  • func (db *Database) Stat(property string) (string, error)
• type Producer
  • func (p *Producer) Names() []string
  • func (p *Producer) OpenDB(name string) (kvdb.DropableStore, error)
• type Snapshot
  • func (s *Snapshot) Get(key []byte) (value []byte, err error)
  • func (s *Snapshot) Has(key []byte) (ret bool, err error)
  • func (s *Snapshot) NewIterator(prefix []byte, start []byte) kvdb.Iterator
  • func (s *Snapshot) Release()
  • func (s *Snapshot) String() string

Functions

func NewProducer

func NewProducer(datadir string, getCache func(string) int) kvdb.IterableDBProducer

NewProducer of level db.

Types

type Database

type Database struct {
	// contains filtered or unexported fields
}

Database is a persistent key-value store. Apart from basic data storage functionality it also supports batch writes and iterating over the keyspace in binary-alphabetical order.

func New

func New(path string, cache int, handles int, close func() error, drop func()) (*Database, error)

New returns a wrapped LevelDB object. The namespace is the prefix that the metrics reporting should use for surfacing internal stats.

func (*Database) Close

func (db *Database) Close() error

Close stops the metrics collection, flushes any pending data to disk and closes all io accesses to the underlying key-value store.

func (*Database) Compact

func (db *Database) Compact(start []byte, limit []byte) error

Compact flattens the underlying data store for the given key range. In essence, deleted and overwritten versions are discarded, and the data is rearranged to reduce the cost of operations needed to access them.

A nil start is treated as a key before all keys in the data store; a nil limit is treated as a key after all keys in the data store. If both is nil then it will compact entire data store.

func (*Database) Delete

func (db *Database) Delete(key []byte) error

Delete removes the key from the key-value store.

func (*Database) Drop

func (db *Database) Drop()

Drop whole database.

func (*Database) Get

func (db *Database) Get(key []byte) ([]byte, error)

Get retrieves the given key if it's present in the key-value store.

func (*Database) GetSnapshot

func (db *Database) GetSnapshot() (kvdb.Snapshot, error)

GetSnapshot returns a latest snapshot of the underlying DB. A snapshot is a frozen snapshot of a DB state at a particular point in time. The content of snapshot are guaranteed to be consistent.

The snapshot must be released after use, by calling Release method.

func (*Database) Has

func (db *Database) Has(key []byte) (bool, error)

Has retrieves if a key is present in the key-value store.

func (*Database) NewBatch

func (db *Database) NewBatch() kvdb.Batch

NewBatch creates a write-only key-value store that buffers changes to its host database until a final write is called.

func (*Database) NewIterator

func (db *Database) NewIterator(prefix []byte, start []byte) kvdb.Iterator

NewIterator creates a binary-alphabetical iterator over a subset of database content with a particular key prefix, starting at a particular initial key (or after, if it does not exist).

func (*Database) Path

func (db *Database) Path() string

Path returns the path to the database directory.

func (*Database) Put

func (db *Database) Put(key []byte, value []byte) error

Put inserts the given value into the key-value store.

func (*Database) Stat

func (db *Database) Stat(property string) (string, error)

Stat returns a particular internal stat of the database.

type Producer

type Producer struct {
	// contains filtered or unexported fields
}

func (*Producer) Names

func (p *Producer) Names() []string

Names of existing databases.

func (*Producer) OpenDB

func (p *Producer) OpenDB(name string) (kvdb.DropableStore, error)

OpenDB or create db with name.

type Snapshot

type Snapshot struct {
	// contains filtered or unexported fields
}

Snapshot is a DB snapshot.

func (*Snapshot) Get

func (s *Snapshot) Get(key []byte) (value []byte, err error)

Get retrieves the given key if it's present in the key-value store.

func (*Snapshot) Has

func (s *Snapshot) Has(key []byte) (ret bool, err error)

Has retrieves if a key is present in the key-value store.

func (*Snapshot) NewIterator

func (s *Snapshot) NewIterator(prefix []byte, start []byte) kvdb.Iterator

NewIterator creates a binary-alphabetical iterator over a subset of database content with a particular key prefix, starting at a particular initial key (or after, if it does not exist).

func (*Snapshot) Release

func (s *Snapshot) Release()

Release releases the snapshot. This will not release any returned iterators, the iterators would still be valid until released or the underlying DB is closed.

Other methods should not be called after the snapshot has been released.

func (*Snapshot) String

func (s *Snapshot) String() string