wazero_lmdb

README

Wazero LMDB

A wazero host module, ABI and guest SDK providing LMDB for WASI modules.

First register the host module with the runtime

import (
	"github.com/pantopic/wazero-lmdb"
	"github.com/tetratelabs/wazero"
	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
)

func main() {
	ctx := context.Background()
	r := wazero.NewRuntimeWithConfig(ctx, wazero.NewRuntimeConfig())
	wasi_snapshot_preview1.MustInstantiate(ctx, r)

	module := wazero_lmdb.New()
	module.Register(ctx, r)
	// ...
}

Then you can import the guest SDK into your WASI module to create and manage LMDB environments from WASM.

package main

import (
	"unsafe"

	"github.com/pantopic/wazero-lmdb/lmdb"
)

func main() {}

//export set
func set() {
	lmdb.Open("test", lmdb.Create).Update(func(txn *lmdb.Txn) error {
		txn.Put(txn.DbOpen("dbname", lmdb.Create), []byte(`hello`), []byte(`world`))
		return nil
	})
}

//export get
func get() uint64 {
	var val []byte
	lmdb.Open("test").View(func(txn *lmdb.Txn) {
		val = txn.Get(txn.DbOpen("dbname"), []byte(`hello`))
	})
	return uint64(uintptr(unsafe.Pointer(&val[0])))<<32 + uint64(len(val))
}

The guest SDK has no dependencies outside the Go std lib. The ABI is ~130 lines of code and the SDK is ~200 lines of code so it should be simple to port this guest SDK if you want to use use this Host Module in other guest languages (i.e. Rust). Contributions welcome.

Wazero prides itself on having no dependencies and neither does lmdb-go so your go.sum remains tidy.

Documentation

Index

• Constants
• Variables
• func New(opts ...Option) *module
• type Option
  • func WithCtxKeyBlockDir(key string) Option
  • func WithCtxKeyLocalDir(key string) Option
  • func WithCtxKeyMeta(key string) Option
  • func WithCtxKeyTenantID(key string) Option

Constants

const (
	// Flag for EnvOpen indicating selection of block storage directory rather than local storage.
	Block uint = 1 << 31
)

Variables

var (
	DefaultCtxKeyMeta     = `module_lmdb_meta`
	DefaultCtxKeyTenantID = `tenant_id`
	DefaultCtxKeyLocalDir = `tenant_local_dir`
	DefaultCtxKeyBlockDir = `tenant_block_dir`
)

Functions

func New

func New(opts ...Option) *module

Types

type Option

type Option func(*module)

func WithCtxKeyBlockDir

func WithCtxKeyBlockDir(key string) Option

func WithCtxKeyLocalDir

func WithCtxKeyLocalDir(key string) Option

func WithCtxKeyMeta

func WithCtxKeyMeta(key string) Option

func WithCtxKeyTenantID

func WithCtxKeyTenantID(key string) Option