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199 lines
3.5 KiB

package db
import (
"bytes"
"fmt"
"sort"
"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
cwwMutex
}
func NewMemDB() *MemDB {
database := &MemDB{
db: make(map[string][]byte),
cwwMutex: NewCWWMutex(),
}
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.SetNoLock(key, value)
}
func (db *MemDB) SetSync(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.SetNoLock(key, value)
}
// NOTE: Implements atomicSetDeleter
func (db *MemDB) SetNoLock(key []byte, value []byte) {
if value == nil {
value = []byte{}
}
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))
}
// NOTE: Implements atomicSetDeleter
func (db *MemDB) DeleteNoLock(key []byte) {
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 {
db.mtx.Lock()
defer db.mtx.Unlock()
stats := make(map[string]string)
stats["database.type"] = "memDB"
stats["database.size"] = fmt.Sprintf("%d", len(db.db))
return stats
}
func (db *MemDB) NewBatch() Batch {
db.mtx.Lock()
defer db.mtx.Unlock()
return &memBatch{db, nil}
}
func (db *MemDB) Mutex() *sync.Mutex {
return &(db.mtx)
}
func (db *MemDB) CacheDB() CacheDB {
return NewCacheDB(db, db.GetWriteLockVersion())
}
//----------------------------------------
func (db *MemDB) Iterator() Iterator {
it := newMemDBIterator()
it.db = db
it.cur = 0
db.mtx.Lock()
defer db.mtx.Unlock()
// We need a copy of all of the keys.
// Not the best, but probably not a bottleneck depending.
for key, _ := range db.db {
it.keys = append(it.keys, key)
}
sort.Strings(it.keys)
return it
}
type memDBIterator struct {
cur int
keys []string
db DB
}
func newMemDBIterator() *memDBIterator {
return &memDBIterator{}
}
func (it *memDBIterator) Seek(key []byte) {
for i, ik := range it.keys {
it.cur = i
if bytes.Compare(key, []byte(ik)) <= 0 {
return
}
}
it.cur += 1 // If not found, becomes invalid.
}
func (it *memDBIterator) Valid() bool {
return 0 <= it.cur && it.cur < len(it.keys)
}
func (it *memDBIterator) Next() {
if !it.Valid() {
panic("memDBIterator Next() called when invalid")
}
it.cur++
}
func (it *memDBIterator) Prev() {
if !it.Valid() {
panic("memDBIterator Next() called when invalid")
}
it.cur--
}
func (it *memDBIterator) Key() []byte {
if !it.Valid() {
panic("memDBIterator Key() called when invalid")
}
return []byte(it.keys[it.cur])
}
func (it *memDBIterator) Value() []byte {
if !it.Valid() {
panic("memDBIterator Value() called when invalid")
}
return it.db.Get(it.Key())
}
func (it *memDBIterator) Close() {
it.db = nil
it.keys = nil
}
func (it *memDBIterator) GetError() error {
return nil
}