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180 lines
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package db
import (
"fmt"
"sort"
"strings"
"sync"
)
func init() {
registerDBCreator(MemDBBackendStr, func(name string, dir string) (DB, error) {
return NewMemDB(), nil
}, false)
}
type MemDB struct {
mtx sync.Mutex
db map[string][]byte
}
func NewMemDB() *MemDB {
database := &MemDB{db: make(map[string][]byte)}
return database
}
func (db *MemDB) Get(key []byte) []byte {
db.mtx.Lock()
defer db.mtx.Unlock()
return db.db[string(key)]
}
func (db *MemDB) Set(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.db[string(key)] = value
}
func (db *MemDB) SetSync(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.db[string(key)] = value
}
func (db *MemDB) Delete(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
delete(db.db, string(key))
}
func (db *MemDB) DeleteSync(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
delete(db.db, string(key))
}
func (db *MemDB) Close() {
// Close is a noop since for an in-memory
// database, we don't have a destination
// to flush contents to nor do we want
// any data loss on invoking Close()
// See the discussion in https://github.com/tendermint/tmlibs/pull/56
}
func (db *MemDB) Print() {
db.mtx.Lock()
defer db.mtx.Unlock()
for key, value := range db.db {
fmt.Printf("[%X]:\t[%X]\n", []byte(key), value)
}
}
func (db *MemDB) Stats() map[string]string {
stats := make(map[string]string)
stats["database.type"] = "memDB"
return stats
}
type memDBIterator struct {
last int
keys []string
db *MemDB
}
func newMemDBIterator() *memDBIterator {
return &memDBIterator{}
}
func (it *memDBIterator) Next() bool {
if it.last >= len(it.keys)-1 {
return false
}
it.last++
return true
}
func (it *memDBIterator) Key() []byte {
return []byte(it.keys[it.last])
}
func (it *memDBIterator) Value() []byte {
return it.db.Get(it.Key())
}
func (it *memDBIterator) Release() {
it.db = nil
it.keys = nil
}
func (it *memDBIterator) Error() error {
return nil
}
func (db *MemDB) Iterator() Iterator {
return db.IteratorPrefix([]byte{})
}
func (db *MemDB) IteratorPrefix(prefix []byte) Iterator {
it := newMemDBIterator()
it.db = db
it.last = -1
db.mtx.Lock()
defer db.mtx.Unlock()
// unfortunately we need a copy of all of the keys
for key, _ := range db.db {
if strings.HasPrefix(key, string(prefix)) {
it.keys = append(it.keys, key)
}
}
// and we need to sort them
sort.Strings(it.keys)
return it
}
func (db *MemDB) NewBatch() Batch {
return &memDBBatch{db, nil}
}
//--------------------------------------------------------------------------------
type memDBBatch struct {
db *MemDB
ops []operation
}
type opType int
const (
opTypeSet = 1
opTypeDelete = 2
)
type operation struct {
opType
key []byte
value []byte
}
func (mBatch *memDBBatch) Set(key, value []byte) {
mBatch.ops = append(mBatch.ops, operation{opTypeSet, key, value})
}
func (mBatch *memDBBatch) Delete(key []byte) {
mBatch.ops = append(mBatch.ops, operation{opTypeDelete, key, nil})
}
func (mBatch *memDBBatch) Write() {
mBatch.db.mtx.Lock()
defer mBatch.db.mtx.Unlock()
for _, op := range mBatch.ops {
if op.opType == opTypeSet {
mBatch.db.db[string(op.key)] = op.value
} else if op.opType == opTypeDelete {
delete(mBatch.db.db, string(op.key))
}
}
}