LevelDB

A fast key-value DB using syndtr/goleveldb

Table of Contents

• Signatures
• Installation
• Examples
• Config
• Default Config

Signatures

func New(config ...Config) Storage
func (s *Storage) Get(key string) ([]byte, error)
func (s *Storage) GetWithContext(ctx context.Context, key string) ([]byte, error)
func (s *Storage) Set(key string, val []byte, exp time.Duration) error
func (s *Storage) SetWithContext(ctx context.Context, key string, val []byte, exp time.Duration) error
func (s *Storage) Delete(key string) error
func (s *Storage) DeleteWithContext(ctx context.Context, key string) error
func (s *Storage) Reset() error
func (s *Storage) ResetWithContext(ctx context.Context) error
func (s *Storage) Close() error
func (s *Storage) Conn() *leveldb.DB

Note: The context methods are dummy methods and don't have any functionality, as LevelDB does not support context cancellation in its client library. They are provided for compliance with the Fiber storage interface.

Installation

LevelDB is tested on the 2 last Go versions with support for modules. So make sure to initialize one first if you didn't do that yet:

go mod init github.com/<user>/<repo>

And then install the leveldb implementation:

go get github.com/gofiber/storage/leveldb

Examples

Import the storage package.

import "github.com/gofiber/storage/leveldb"

You can use the following possibilities to create a storage:

// Initialize default config
store := leveldb.New()

// Initialize custom config
store := leveldb.New(leveldb.Config{
	Path: "./testdb",
	GCInterval: 10 * time.Second,
})

Config

type Config struct {
	// Path is the filesystem path for the database
	//
	// Optional. Default is "./fiber.leveldb"
	Path string

	// CacheSize is the size of LevelDB's cache (in MB)
	//
	// Optional. Default is 8MB
	CacheSize int

	// BlockSize is the size of data blocks (in KB)
	//
	// Optional. Default is 4KB
	BlockSize int

	// WriteBuffer is the size of write buffer (in MB)
	//
	// Optional. Default is 4MB
	WriteBuffer int

	// CompactionL0Trigger is the number of level-0 tables that triggers compaction
	//
	// Optional. Default is 4
	CompactionL0Trigger int

	// WriteL0PauseTrigger is the number of level-0 tables that triggers write pause
	//
	// Optional. Default is 12
	WriteL0PauseTrigger int

	// WriteL0SlowdownTrigger is the number of level-0 tables that triggers write slowdown
	//
	// Optional. Default is 8
	WriteL0SlowdownTrigger int

	// MaxOpenFiles is the maximum number of open files that can be held
	//
	// Optional. Default is 200 on MacOS, 500 on others
	MaxOpenFiles int

	// CompactionTableSize is the size of compaction table (in MB)
	//
	// Optional. Default is 2MB
	CompactionTableSize int

	// BloomFilterBits is the number of bits used in bloom filter
	//
	// Optional. Default is 10 bits/key
	BloomFilterBits int

	// NoSync completely disables fsync
	//
	// Optional. Default is false
	NoSync bool

	// ReadOnly opens the database in read-only mode
	//
	// Optional. Default is false
	ReadOnly bool

	// ErrorIfMissing returns error if database doesn't exist
	//
	// Optional. Default is false
	ErrorIfMissing bool

	// ErrorIfExist returns error if database exists
	//
	// Optional. Default is false
	ErrorIfExist bool

	// GCInterval is the garbage collection interval
	//
	// Optional. Default is 10 minutes
	GCInterval time.Duration
}

Default Config

var ConfigDefault = Config{
	Path:                 "./fiber.leveldb",
	CacheSize:              8, // 8 MB
	BlockSize:              4, // 4 KB
	WriteBuffer:            4, // 4 MB
	CompactionL0Trigger:    4,
	WriteL0PauseTrigger:    12,
	WriteL0SlowdownTrigger: 8,
	MaxOpenFiles: func() int {
		if runtime.GOOS == "darwin" {
			return 200 // MacOS
		}
		return 500 // Unix/Linux
	}(),
	CompactionTableSize: 2,  // 2 MB
	BloomFilterBits:     10, // 10 bits per key
	NoSync:              false,
	ReadOnly:            false,
	ErrorIfMissing:      false,
	ErrorIfExist:        false,
	GCInterval:          10 * time.Minute,
}