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package ethdb
import (
"sync"
"github.com/ethereum/go-ethereum/compression/rle"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/iterator"
"github.com/syndtr/goleveldb/leveldb/opt"
)
var OpenFileLimit = 64
type LDBDatabase struct {
fn string
mu sync.Mutex
db *leveldb.DB
queue map[string][]byte
quit chan struct{}
}
// NewLDBDatabase returns a LevelDB wrapped object. LDBDatabase does not persist data by
// it self but requires a background poller which syncs every X. `Flush` should be called
// when data needs to be stored and written to disk.
func NewLDBDatabase(file string) (*LDBDatabase, error) {
// Open the db
db, err := leveldb.OpenFile(file, &opt.Options{OpenFilesCacheCapacity: OpenFileLimit})
// check for curruption and attempt to recover
if _, iscorrupted := err.(*errors.ErrCorrupted); iscorrupted {
db, err = leveldb.RecoverFile(file, nil)
}
// (re) check for errors and abort if opening of the db failed
if err != nil {
return nil, err
}
database := &LDBDatabase{
fn: file,
db: db,
quit: make(chan struct{}),
}
database.makeQueue()
return database, nil
}
func (self *LDBDatabase) makeQueue() {
self.queue = make(map[string][]byte)
}
// Put puts the given key / value to the queue
func (self *LDBDatabase) Put(key []byte, value []byte) {
self.mu.Lock()
defer self.mu.Unlock()
self.queue[string(key)] = value
}
// Get returns the given key if it's present.
func (self *LDBDatabase) Get(key []byte) ([]byte, error) {
self.mu.Lock()
defer self.mu.Unlock()
// Check queue first
if dat, ok := self.queue[string(key)]; ok {
return dat, nil
}
dat, err := self.db.Get(key, nil)
if err != nil {
return nil, err
}
return rle.Decompress(dat)
}
// Delete deletes the key from the queue and database
func (self *LDBDatabase) Delete(key []byte) error {
self.mu.Lock()
defer self.mu.Unlock()
// make sure it's not in the queue
delete(self.queue, string(key))
return self.db.Delete(key, nil)
}
func (self *LDBDatabase) LastKnownTD() []byte {
data, _ := self.Get([]byte("LTD"))
if len(data) == 0 {
data = []byte{0x0}
}
return data
}
func (self *LDBDatabase) NewIterator() iterator.Iterator {
return self.db.NewIterator(nil, nil)
}
// Flush flushes out the queue to leveldb
func (self *LDBDatabase) Flush() error {
self.mu.Lock()
defer self.mu.Unlock()
batch := new(leveldb.Batch)
for key, value := range self.queue {
batch.Put([]byte(key), rle.Compress(value))
}
self.makeQueue() // reset the queue
glog.V(logger.Detail).Infoln("Flush database: ", self.fn)
return self.db.Write(batch, nil)
}
func (self *LDBDatabase) Close() {
if err := self.Flush(); err != nil {
glog.V(logger.Error).Infof("error: flush '%s': %v\n", self.fn, err)
}
self.db.Close()
glog.V(logger.Error).Infoln("flushed and closed db:", self.fn)
}
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