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4.8 KiB

package db
import (
"fmt"
"sort"
"sync"
)
func init() {
registerDBCreator(MemDBBackend, func(name, dir string) (DB, error) {
return NewMemDB(), nil
}, false)
}
var _ DB = (*MemDB)(nil)
type MemDB struct {
mtx sync.Mutex
db map[string][]byte
}
func NewMemDB() *MemDB {
database := &MemDB{
db: make(map[string][]byte),
}
return database
}
// Implements atomicSetDeleter.
func (db *MemDB) Mutex() *sync.Mutex {
return &(db.mtx)
}
// Implements DB.
func (db *MemDB) Get(key []byte) []byte {
db.mtx.Lock()
defer db.mtx.Unlock()
key = nonNilBytes(key)
value := db.db[string(key)]
return value
}
// Implements DB.
func (db *MemDB) Has(key []byte) bool {
db.mtx.Lock()
defer db.mtx.Unlock()
key = nonNilBytes(key)
_, ok := db.db[string(key)]
return ok
}
// Implements DB.
func (db *MemDB) Set(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.SetNoLock(key, value)
}
// Implements DB.
func (db *MemDB) SetSync(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.SetNoLock(key, value)
}
// Implements atomicSetDeleter.
func (db *MemDB) SetNoLock(key []byte, value []byte) {
db.SetNoLockSync(key, value)
}
// Implements atomicSetDeleter.
func (db *MemDB) SetNoLockSync(key []byte, value []byte) {
key = nonNilBytes(key)
value = nonNilBytes(value)
db.db[string(key)] = value
}
// Implements DB.
func (db *MemDB) Delete(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.DeleteNoLock(key)
}
// Implements DB.
func (db *MemDB) DeleteSync(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.DeleteNoLock(key)
}
// Implements atomicSetDeleter.
func (db *MemDB) DeleteNoLock(key []byte) {
db.DeleteNoLockSync(key)
}
// Implements atomicSetDeleter.
func (db *MemDB) DeleteNoLockSync(key []byte) {
key = nonNilBytes(key)
delete(db.db, string(key))
}
// Implements DB.
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/tendermint/libs/pull/56
}
// Implements DB.
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)
}
}
// Implements DB.
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
}
// Implements DB.
func (db *MemDB) NewBatch() Batch {
db.mtx.Lock()
defer db.mtx.Unlock()
return &memBatch{db, nil}
}
//----------------------------------------
// Iterator
// Implements DB.
func (db *MemDB) Iterator(start, end []byte) Iterator {
db.mtx.Lock()
defer db.mtx.Unlock()
keys := db.getSortedKeys(start, end, false)
return newMemDBIterator(db, keys, start, end)
}
// Implements DB.
func (db *MemDB) ReverseIterator(start, end []byte) Iterator {
db.mtx.Lock()
defer db.mtx.Unlock()
keys := db.getSortedKeys(start, end, true)
return newMemDBIterator(db, keys, start, end)
}
// We need a copy of all of the keys.
// Not the best, but probably not a bottleneck depending.
type memDBIterator struct {
db DB
cur int
keys []string
start []byte
end []byte
}
var _ Iterator = (*memDBIterator)(nil)
// Keys is expected to be in reverse order for reverse iterators.
func newMemDBIterator(db DB, keys []string, start, end []byte) *memDBIterator {
return &memDBIterator{
db: db,
cur: 0,
keys: keys,
start: start,
end: end,
}
}
// Implements Iterator.
func (itr *memDBIterator) Domain() ([]byte, []byte) {
return itr.start, itr.end
}
// Implements Iterator.
func (itr *memDBIterator) Valid() bool {
return 0 <= itr.cur && itr.cur < len(itr.keys)
}
// Implements Iterator.
func (itr *memDBIterator) Next() {
itr.assertIsValid()
itr.cur++
}
// Implements Iterator.
func (itr *memDBIterator) Key() []byte {
itr.assertIsValid()
return []byte(itr.keys[itr.cur])
}
// Implements Iterator.
func (itr *memDBIterator) Value() []byte {
itr.assertIsValid()
key := []byte(itr.keys[itr.cur])
return itr.db.Get(key)
}
// Implements Iterator.
func (itr *memDBIterator) Close() {
itr.keys = nil
itr.db = nil
}
func (itr *memDBIterator) assertIsValid() {
if !itr.Valid() {
panic("memDBIterator is invalid")
}
}
//----------------------------------------
// Misc.
func (db *MemDB) getSortedKeys(start, end []byte, reverse bool) []string {
keys := []string{}
for key := range db.db {
inDomain := IsKeyInDomain([]byte(key), start, end)
if inDomain {
keys = append(keys, key)
}
}
sort.Strings(keys)
if reverse {
nkeys := len(keys)
for i := 0; i < nkeys/2; i++ {
temp := keys[i]
keys[i] = keys[nkeys-i-1]
keys[nkeys-i-1] = temp
}
}
return keys
}