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package db
import (
"fmt"
"io/ioutil"
"net/url"
"os"
"path/filepath"
"sort"
"sync"
"github.com/pkg/errors"
cmn "github.com/tendermint/tmlibs/common"
)
const (
keyPerm = os.FileMode(0600)
dirPerm = os.FileMode(0700)
)
func init() {
registerDBCreator(FSDBBackendStr, func(name string, dir string) (DB, error) {
dbPath := filepath.Join(dir, name+".db")
return NewFSDB(dbPath), nil
}, false)
}
var _ DB = (*FSDB)(nil)
// It's slow.
type FSDB struct {
mtx sync.Mutex
dir string
}
func NewFSDB(dir string) *FSDB {
err := os.MkdirAll(dir, dirPerm)
if err != nil {
panic(errors.Wrap(err, "Creating FSDB dir "+dir))
}
database := &FSDB{
dir: dir,
}
return database
}
func (db *FSDB) Get(key []byte) []byte {
db.mtx.Lock()
defer db.mtx.Unlock()
key = escapeKey(key)
path := db.nameToPath(key)
value, err := read(path)
if os.IsNotExist(err) {
return nil
} else if err != nil {
panic(errors.Wrapf(err, "Getting key %s (0x%X)", string(key), key))
}
return value
}
func (db *FSDB) Has(key []byte) bool {
db.mtx.Lock()
defer db.mtx.Unlock()
key = escapeKey(key)
path := db.nameToPath(key)
return cmn.FileExists(path)
}
func (db *FSDB) Set(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.SetNoLock(key, value)
}
func (db *FSDB) SetSync(key []byte, value []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.SetNoLock(key, value)
}
// NOTE: Implements atomicSetDeleter.
func (db *FSDB) SetNoLock(key []byte, value []byte) {
key = escapeKey(key)
value = nonNilBytes(value)
path := db.nameToPath(key)
err := write(path, value)
if err != nil {
panic(errors.Wrapf(err, "Setting key %s (0x%X)", string(key), key))
}
}
func (db *FSDB) Delete(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.DeleteNoLock(key)
}
func (db *FSDB) DeleteSync(key []byte) {
db.mtx.Lock()
defer db.mtx.Unlock()
db.DeleteNoLock(key)
}
// NOTE: Implements atomicSetDeleter.
func (db *FSDB) DeleteNoLock(key []byte) {
key = escapeKey(key)
path := db.nameToPath(key)
err := remove(path)
if os.IsNotExist(err) {
return
} else if err != nil {
panic(errors.Wrapf(err, "Removing key %s (0x%X)", string(key), key))
}
}
func (db *FSDB) Close() {
// Nothing to do.
}
func (db *FSDB) Print() {
db.mtx.Lock()
defer db.mtx.Unlock()
panic("FSDB.Print not yet implemented")
}
func (db *FSDB) Stats() map[string]string {
db.mtx.Lock()
defer db.mtx.Unlock()
panic("FSDB.Stats not yet implemented")
}
func (db *FSDB) NewBatch() Batch {
db.mtx.Lock()
defer db.mtx.Unlock()
// Not sure we would ever want to try...
// It doesn't seem easy for general filesystems.
panic("FSDB.NewBatch not yet implemented")
}
func (db *FSDB) Mutex() *sync.Mutex {
return &(db.mtx)
}
func (db *FSDB) Iterator(start, end []byte) Iterator {
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.
keys, err := list(db.dir, start, end)
if err != nil {
panic(errors.Wrapf(err, "Listing keys in %s", db.dir))
}
sort.Strings(keys)
return newMemDBIterator(db, keys, start, end)
}
func (db *FSDB) ReverseIterator(start, end []byte) Iterator {
panic("not implemented yet") // XXX
}
func (db *FSDB) nameToPath(name []byte) string {
n := url.PathEscape(string(name))
return filepath.Join(db.dir, n)
}
// Read some bytes to a file.
// CONTRACT: returns os errors directly without wrapping.
func read(path string) ([]byte, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
d, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
return d, nil
}
// Write some bytes from a file.
// CONTRACT: returns os errors directly without wrapping.
func write(path string, d []byte) error {
f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, keyPerm)
if err != nil {
return err
}
defer f.Close()
_, err = f.Write(d)
if err != nil {
return err
}
err = f.Sync()
return err
}
// Remove a file.
// CONTRACT: returns os errors directly without wrapping.
func remove(path string) error {
return os.Remove(path)
}
// List keys in a directory, stripping of escape sequences and dir portions.
// CONTRACT: returns os errors directly without wrapping.
func list(dirPath string, start, end []byte) ([]string, error) {
dir, err := os.Open(dirPath)
if err != nil {
return nil, err
}
defer dir.Close()
names, err := dir.Readdirnames(0)
if err != nil {
return nil, err
}
var keys []string
for _, name := range names {
n, err := url.PathUnescape(name)
if err != nil {
return nil, fmt.Errorf("Failed to unescape %s while listing", name)
}
key := unescapeKey([]byte(n))
if IsKeyInDomain(key, start, end, false) {
keys = append(keys, string(key))
}
}
return keys, nil
}
// To support empty or nil keys, while the file system doesn't allow empty
// filenames.
func escapeKey(key []byte) []byte {
return []byte("k_" + string(key))
}
func unescapeKey(escKey []byte) []byte {
if len(escKey) < 2 {
panic(fmt.Sprintf("Invalid esc key: %x", escKey))
}
if string(escKey[:2]) != "k_" {
panic(fmt.Sprintf("Invalid esc key: %x", escKey))
}
return escKey[2:]
}