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// Copyright (c) 2013, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package storage
import (
"bytes"
"os"
"sync"
"github.com/syndtr/goleveldb/leveldb/util"
)
const typeShift = 3
type memStorageLock struct {
ms *memStorage
}
func (lock *memStorageLock) Release() {
ms := lock.ms
ms.mu.Lock()
defer ms.mu.Unlock()
if ms.slock == lock {
ms.slock = nil
}
return
}
// memStorage is a memory-backed storage.
type memStorage struct {
mu sync.Mutex
slock *memStorageLock
files map[uint64]*memFile
manifest *memFilePtr
}
// NewMemStorage returns a new memory-backed storage implementation.
func NewMemStorage() Storage {
return &memStorage{
files: make(map[uint64]*memFile),
}
}
func (ms *memStorage) Lock() (util.Releaser, error) {
ms.mu.Lock()
defer ms.mu.Unlock()
if ms.slock != nil {
return nil, ErrLocked
}
ms.slock = &memStorageLock{ms: ms}
return ms.slock, nil
}
func (*memStorage) Log(str string) {}
func (ms *memStorage) GetFile(num uint64, t FileType) File {
return &memFilePtr{ms: ms, num: num, t: t}
}
func (ms *memStorage) GetFiles(t FileType) ([]File, error) {
ms.mu.Lock()
var ff []File
for x, _ := range ms.files {
num, mt := x>>typeShift, FileType(x)&TypeAll
if mt&t == 0 {
continue
}
ff = append(ff, &memFilePtr{ms: ms, num: num, t: mt})
}
ms.mu.Unlock()
return ff, nil
}
func (ms *memStorage) GetManifest() (File, error) {
ms.mu.Lock()
defer ms.mu.Unlock()
if ms.manifest == nil {
return nil, os.ErrNotExist
}
return ms.manifest, nil
}
func (ms *memStorage) SetManifest(f File) error {
fm, ok := f.(*memFilePtr)
if !ok || fm.t != TypeManifest {
return ErrInvalidFile
}
ms.mu.Lock()
ms.manifest = fm
ms.mu.Unlock()
return nil
}
func (*memStorage) Close() error { return nil }
type memReader struct {
*bytes.Reader
m *memFile
}
func (mr *memReader) Close() error {
return mr.m.Close()
}
type memFile struct {
bytes.Buffer
ms *memStorage
open bool
}
func (*memFile) Sync() error { return nil }
func (m *memFile) Close() error {
m.ms.mu.Lock()
m.open = false
m.ms.mu.Unlock()
return nil
}
type memFilePtr struct {
ms *memStorage
num uint64
t FileType
}
func (p *memFilePtr) x() uint64 {
return p.Num()<<typeShift | uint64(p.Type())
}
func (p *memFilePtr) Open() (Reader, error) {
ms := p.ms
ms.mu.Lock()
defer ms.mu.Unlock()
if m, exist := ms.files[p.x()]; exist {
if m.open {
return nil, errFileOpen
}
m.open = true
return &memReader{Reader: bytes.NewReader(m.Bytes()), m: m}, nil
}
return nil, os.ErrNotExist
}
func (p *memFilePtr) Create() (Writer, error) {
ms := p.ms
ms.mu.Lock()
defer ms.mu.Unlock()
m, exist := ms.files[p.x()]
if exist {
if m.open {
return nil, errFileOpen
}
m.Reset()
} else {
m = &memFile{ms: ms}
ms.files[p.x()] = m
}
m.open = true
return m, nil
}
func (p *memFilePtr) Replace(newfile File) error {
p1, ok := newfile.(*memFilePtr)
if !ok {
return ErrInvalidFile
}
ms := p.ms
ms.mu.Lock()
defer ms.mu.Unlock()
m1, exist := ms.files[p1.x()]
if !exist {
return os.ErrNotExist
}
m0, exist := ms.files[p.x()]
if (exist && m0.open) || m1.open {
return errFileOpen
}
delete(ms.files, p1.x())
ms.files[p.x()] = m1
return nil
}
func (p *memFilePtr) Type() FileType {
return p.t
}
func (p *memFilePtr) Num() uint64 {
return p.num
}
func (p *memFilePtr) Remove() error {
ms := p.ms
ms.mu.Lock()
defer ms.mu.Unlock()
if _, exist := ms.files[p.x()]; exist {
delete(ms.files, p.x())
return nil
}
return os.ErrNotExist
}
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