示例#1
0
文件: dbm.go 项目: pmezard/exp
// Open opens the named DB file for reading/writing. If successful, methods on
// the returned DB can be used for I/O; the associated file descriptor has mode
// os.O_RDWR. If there is an error, it will be of type *os.PathError.
//
// For the meaning of opts please see documentation of Options.
func Open(name string, opts *Options) (db *DB, err error) {
	defer func() {
		lock := opts.lock
		if err != nil && lock != nil {
			n := lock.Name()
			lock.Close()
			os.Remove(n)
			db = nil
		}
		if err != nil {
			if db != nil {
				db.Close()
				db = nil
			}
		}
	}()

	if err = opts.check(name, false, true); err != nil {
		return
	}

	f, err := os.OpenFile(name, os.O_RDWR, 0666)
	if err != nil {
		return
	}

	filer := lldb.Filer(lldb.NewSimpleFileFiler(f))
	sz, err := filer.Size()
	if err != nil {
		return
	}

	if sz%16 != 0 {
		return nil, &os.PathError{Op: "dbm.Open:", Path: name, Err: fmt.Errorf("file size %d(%#x) is not 0 (mod 16)", sz, sz)}
	}

	var b [16]byte
	if n, err := filer.ReadAt(b[:], 0); n != 16 || err != nil {
		return nil, &os.PathError{Op: "dbm.Open.ReadAt", Path: name, Err: err}
	}

	var h header
	if err = h.rd(b[:]); err != nil {
		return nil, &os.PathError{Op: "dbm.Open:validate header", Path: name, Err: err}
	}

	db = &DB{f: f, lock: opts.lock, closed: make(chan bool)}
	if filer, err = opts.acidFiler(db, filer); err != nil {
		return nil, err
	}

	db.filer = filer
	switch h.ver {
	default:
		return nil, &os.PathError{Op: "dbm.Open", Path: name, Err: fmt.Errorf("unknown dbm file format version %#x", h.ver)}
	case 0x00:
		return open00(name, db)
	}

}
示例#2
0
文件: file.go 项目: uabassguy/ql
func newFileFromOSFile(f lldb.OSFile) (fi *file, err error) {
	nm := lockName(f.Name())
	lck, err := lock.Lock(nm)
	if err != nil {
		if lck != nil {
			lck.Close()
		}
		return nil, err
	}

	close := true
	defer func() {
		if close && lck != nil {
			lck.Close()
		}
	}()

	var w *os.File
	closew := false
	wn := walName(f.Name())
	w, err = os.OpenFile(wn, os.O_CREATE|os.O_EXCL|os.O_RDWR, 0666)
	closew = true
	defer func() {
		if closew {
			nm := w.Name()
			w.Close()
			os.Remove(nm)
			w = nil
		}
	}()

	if err != nil {
		if !os.IsExist(err) {
			return nil, err
		}

		closew = false
		w, err = os.OpenFile(wn, os.O_RDWR, 0666)
		if err != nil {
			return nil, err
		}

		closew = true
		st, err := w.Stat()
		if err != nil {
			return nil, err
		}

		if st.Size() != 0 {
			return nil, fmt.Errorf("non empty WAL file %s exists", wn)
		}
	}

	info, err := f.Stat()
	if err != nil {
		return nil, err
	}

	switch sz := info.Size(); {
	case sz == 0:
		b := make([]byte, 16)
		copy(b, []byte(magic))
		if _, err := f.Write(b); err != nil {
			return nil, err
		}

		filer := lldb.Filer(lldb.NewOSFiler(f))
		filer = lldb.NewInnerFiler(filer, 16)
		if filer, err = lldb.NewACIDFiler(filer, w); err != nil {
			return nil, err
		}

		a, err := lldb.NewAllocator(filer, &lldb.Options{})
		if err != nil {
			return nil, err
		}

		a.Compress = true
		s := &file{
			a:     a,
			codec: newGobCoder(),
			f0:    f,
			f:     filer,
			lck:   lck,
			name:  f.Name(),
			wal:   w,
		}
		if err = s.BeginTransaction(); err != nil {
			return nil, err
		}

		h, err := s.Create()
		if err != nil {
			return nil, err
		}

		if h != 1 { // root
			log.Panic("internal error")
		}

		if h, err = s.a.Alloc(make([]byte, 8)); err != nil {
			return nil, err
		}

		if h != 2 { // id
			log.Panic("internal error")
		}

		close, closew = false, false
		return s, s.Commit()
	default:
		b := make([]byte, 16)
		if _, err := f.Read(b); err != nil {
			return nil, err
		}

		if string(b[:len(magic)]) != magic {
			return nil, fmt.Errorf("unknown file format")
		}

		filer := lldb.Filer(lldb.NewOSFiler(f))
		filer = lldb.NewInnerFiler(filer, 16)
		if filer, err = lldb.NewACIDFiler(filer, w); err != nil {
			return nil, err
		}

		a, err := lldb.NewAllocator(filer, &lldb.Options{})
		if err != nil {
			return nil, err
		}

		bid, err := a.Get(nil, 2) // id
		if err != nil {
			return nil, err
		}

		if len(bid) != 8 {
			return nil, fmt.Errorf("corrupted id |% x|", bid)
		}

		id := int64(0)
		for _, v := range bid {
			id = (id << 8) | int64(v)
		}

		a.Compress = true
		s := &file{
			a:     a,
			codec: newGobCoder(),
			f0:    f,
			f:     filer,
			id:    id,
			lck:   lck,
			name:  f.Name(),
			wal:   w,
		}

		close, closew = false, false
		return s, nil
	}
}
示例#3
0
文件: kv.go 项目: mervin0502/kv
// Open opens the named DB file for reading/writing. If successful, methods on
// the returned DB can be used for I/O; the associated file descriptor has mode
// os.O_RDWR. If there is an error, it will be of type *os.PathError.
//
// Note: While a DB is opened, it is locked and cannot be simultaneously opened
// again.
//
// For the meaning of opts please see documentation of Options.
func Open(name string, opts *Options) (db *DB, err error) {
	opts = opts.clone()
	opts._ACID = _ACIDFull
	defer func() {
		if db != nil {
			db.opts = opts
		}
	}()
	defer func() {
		lock := opts.lock
		if err != nil && lock != nil {
			lock.Close()
			db = nil
		}
		if err != nil {
			if db != nil {
				db.Close()
				db = nil
			}
		}
	}()

	if err = opts.check(name, false, true); err != nil {
		return
	}

	f, err := os.OpenFile(name, os.O_RDWR, 0666)
	if err != nil {
		return
	}

	filer := lldb.Filer(lldb.NewSimpleFileFiler(f))
	sz, err := filer.Size()
	if err != nil {
		return
	}

	if sz%16 != 0 {
		return nil, &os.PathError{Op: "kv.Open:", Path: name, Err: fmt.Errorf("file size %d(%#x) is not 0 (mod 16)", sz, sz)}
	}

	var b [16]byte
	if n, err := filer.ReadAt(b[:], 0); n != 16 || err != nil {
		return nil, &os.PathError{Op: "kv.Open.ReadAt", Path: name, Err: err}
	}

	var h header
	if err = h.rd(b[:]); err != nil {
		return nil, &os.PathError{Op: "kv.Open:validate header", Path: name, Err: err}
	}

	db = &DB{f: f, lock: opts.lock}
	if filer, err = opts.acidFiler(db, filer); err != nil {
		return nil, err
	}

	db.filer = filer
	switch h.ver {
	default:
		return nil, &os.PathError{Op: "kv.Open", Path: name, Err: fmt.Errorf("unknown/unsupported kv file format version %#x", h.ver)}
	case 0x00:
		if _, err = open00(name, db); err != nil {
			return nil, err
		}
	}

	db.root, err = lldb.OpenBTree(db.alloc, opts.Compare, 1)
	db.wal = opts.wal
	if opts.VerifyDbAfterOpen {
		err = verifyAllocator(db.alloc)
	}
	return
}