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badger.go
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badger.go
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package kv
import (
"context"
"net/url"
"runtime"
"time"
"github.com/dgraph-io/badger/v2"
)
const gcWorkers = 2
const gcThreshold = 0.5
const gcInterval = time.Hour * 5
type BadgerDB struct {
*badger.DB
ctx context.Context
cancel func()
}
type badgerTransaction struct {
*badger.Txn
}
type badgerIterator struct {
*badger.Iterator
}
func NewBadgerDbFromUrl(u *url.URL) (*BadgerDB, error) {
var db *badger.DB
var err error
passw, _ := u.User.Password()
passw = passw + "12345678901234567890123456789012" // make sure the password is at least 32 chars by appending a default suffix
if err != nil {
return nil, err
}
path := u.Path
if len(path) > 1 && path[1] == '.' {
path = path[1:]
}
if u.Query().Get("memory") == "true" {
db, err = badger.Open(badger.DefaultOptions("").WithInMemory(true))
} else {
db, err = badger.Open(
badger.DefaultOptions(path).
// Lower RAM usage without mmap
WithNumVersionsToKeep(0).
WithEncryptionKey([]byte(passw)[:32]).
WithTruncate(true), // this would trucate faulty value logs; something that should NOT be problematic with syncWrites(true)
)
}
if err != nil {
return nil, err
}
return NewbadgerFromDB(db)
}
func NewbadgerFromDB(db *badger.DB) (*BadgerDB, error) {
ctx, cancel := context.WithCancel(context.Background())
bdb := &BadgerDB{
db,
ctx,
cancel,
}
go bdb.runGc()
return bdb, nil
}
// TODO: parametrize these constants
func (bdb *BadgerDB) runGc() {
ticker := time.NewTicker(gcInterval)
defer ticker.Stop()
for {
select {
case <-ticker.C:
bdb.DB.Flatten(gcWorkers) // 4 number of workers
var err error
for ; err == nil; err = bdb.DB.RunValueLogGC(gcThreshold) {
}
runtime.GC()
case <-bdb.ctx.Done():
return
}
}
}
// badger db
// Get gets the value of a key within a single query transaction
func (bdb *BadgerDB) Close() error {
return bdb.DB.Close()
}
// Get gets the value of a key within a single query transaction
func (bdb *BadgerDB) Get(ctx context.Context, key []byte) (res []byte, err error) {
err = bdb.DB.View(func(txn *badger.Txn) error {
item, err := txn.Get(key)
if err != nil {
return err
}
res, err = item.ValueCopy(res)
return err
})
if err == badger.ErrKeyNotFound {
err = ErrNotFound
}
return res, err
}
// Put sets the value of a key within a single query transaction
func (bdb *BadgerDB) Put(ctx context.Context, key, value []byte) error {
err := bdb.DB.Update(func(txn *badger.Txn) error {
return txn.Set(key, value)
})
if err == badger.ErrKeyNotFound {
err = ErrNotFound
}
return err
}
// Delete removes a key within a single transaction
func (bdb *BadgerDB) Delete(ctx context.Context, key []byte) error {
return bdb.DB.Update(func(txn *badger.Txn) error {
err := txn.Delete(key)
if err == badger.ErrKeyNotFound {
return ErrNotFound
}
return err
})
}
// NewTransaction for batching multiple values inside a transaction
func (bdb *BadgerDB) NewTransaction(ctx context.Context, readOnly bool) (OrderedTransaction, error) {
return &badgerTransaction{
bdb.DB.NewTransaction(!readOnly),
}, nil
}
// badgerTransaction
// Seeks initializes an iterator at the given key (inclusive)
func (bdb *badgerTransaction) Close() error {
return bdb.Discard(context.Background())
}
// Get gets the value of a key within a single query transaction
func (bdb *badgerTransaction) Get(ctx context.Context, key []byte) (res []byte, err error) {
item, err := bdb.Txn.Get(key)
if err != nil {
if err == badger.ErrKeyNotFound {
err = ErrNotFound
}
return res, err
}
return item.ValueCopy(res)
}
// Put sets the value of a key within a single query transaction
func (bdb *badgerTransaction) Put(ctx context.Context, key, value []byte) error {
err := bdb.Txn.Set(key, value)
if err == badger.ErrKeyNotFound {
err = ErrNotFound
}
return err
}
// Delete removes a key within a single transaction
func (bdb *badgerTransaction) Delete(ctx context.Context, key []byte) error {
err := bdb.Txn.Delete(key)
if err == badger.ErrKeyNotFound {
return ErrNotFound
}
return err
}
func (bdb *badgerTransaction) Seek(ctx context.Context, StartKey []byte) (Iterator, error) {
it := bdb.Txn.NewIterator(badger.DefaultIteratorOptions)
it.Seek(StartKey)
return &badgerIterator{
it,
}, nil
}
// Discard removes all sides effects of the transaction
func (bdb *badgerTransaction) Discard(ctx context.Context) error {
bdb.Txn.Discard()
return nil
}
// Commit persists all side effects of the transaction and returns an error if there are any conflics
func (bdb *badgerTransaction) Commit(ctx context.Context) error {
return bdb.Txn.Commit()
}
// badgerIterator
// Next yeilds the next key-value in iterator. Key-values can not be re-used between iterations. Make sure top copy the values if you must.
func (it *badgerIterator) Next(ctx context.Context) (key, value []byte, err error) {
if !it.Iterator.Valid() {
return nil, nil, ErrNotFound
}
defer it.Iterator.Next()
value, err = it.Iterator.Item().ValueCopy(value)
return it.Iterator.Item().Key(), value, err
}
// Close must always be called to clean up iterators.
func (bdb *badgerIterator) Close() error {
bdb.Iterator.Close()
return nil
}