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DataFile buffered io file wrapper for handling, reading, and writing binary data
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| package db | |
| import ( | |
| "bufio" | |
| "encoding/binary" | |
| "io" | |
| "os" | |
| "path/filepath" | |
| "unsafe" | |
| ) | |
| const blockSZ = 16 | |
| type DataFile struct { | |
| file *os.File | |
| rw *bufio.ReadWriter | |
| } | |
| func OpenDataFile(path string) (*DataFile, error) { | |
| file, err := openFile(path) | |
| if err != nil { | |
| return nil, err | |
| } | |
| r := bufio.NewReaderSize(file, blockSZ) | |
| w := bufio.NewWriterSize(file, blockSZ) | |
| return &DataFile{ | |
| file: file, | |
| rw: bufio.NewReadWriter(r, w), | |
| }, nil | |
| } | |
| func (df *DataFile) Stat() (os.FileInfo, error) { | |
| return df.file.Stat() | |
| } | |
| func (df *DataFile) Read(b []byte) (int, error) { | |
| return df.rw.Read(b) | |
| } | |
| func (df *DataFile) ReadByte() (byte, error) { | |
| return df.rw.ReadByte() | |
| } | |
| func (df *DataFile) ReadBytes() ([]byte, error) { | |
| n, err := df.ReadUvarint() | |
| if err != nil { | |
| return nil, err | |
| } | |
| b := make([]byte, n) | |
| if _, err := io.ReadFull(df.rw, b); err != nil { | |
| return nil, err | |
| } | |
| return b, nil | |
| } | |
| func (df *DataFile) ReadString() (string, error) { | |
| b, err := df.ReadBytes() | |
| if err != nil { | |
| return "", err | |
| } | |
| return *(*string)(unsafe.Pointer(&b)), nil | |
| } | |
| func (df *DataFile) ReadUint16() (uint16, error) { | |
| var buf [2]byte | |
| if _, err := io.ReadFull(df.rw, buf[:]); err != nil { | |
| return 0, err | |
| } | |
| return binary.LittleEndian.Uint16(buf[:]), nil | |
| } | |
| func (df *DataFile) ReadUint32() (uint32, error) { | |
| var buf [4]byte | |
| if _, err := io.ReadFull(df.rw, buf[:]); err != nil { | |
| return 0, err | |
| } | |
| return binary.LittleEndian.Uint32(buf[:]), nil | |
| } | |
| func (df *DataFile) ReadUint64() (uint64, error) { | |
| var buf [8]byte | |
| if _, err := io.ReadFull(df.rw, buf[:]); err != nil { | |
| return 0, err | |
| } | |
| return binary.LittleEndian.Uint64(buf[:]), nil | |
| } | |
| func (df *DataFile) ReadUvarint() (uint64, error) { | |
| return binary.ReadUvarint(df.rw) | |
| } | |
| func (df *DataFile) ReaderBuffered() int { | |
| return df.rw.Reader.Buffered() | |
| } | |
| func (df *DataFile) ReaderSize() int { | |
| return df.rw.Reader.Size() | |
| } | |
| func (df *DataFile) UnreadByte() error { | |
| return df.rw.UnreadByte() | |
| } | |
| func (df *DataFile) Write(b []byte) (int, error) { | |
| return df.rw.Write(b) | |
| } | |
| func (df *DataFile) WriteByte(b byte) error { | |
| return df.rw.WriteByte(b) | |
| } | |
| func (df *DataFile) WriteBytes(b []byte) error { | |
| return df.WriteString(*(*string)(unsafe.Pointer(&b))) | |
| } | |
| func (df *DataFile) WriteString(s string) error { | |
| if err := df.WriteUvarint(uint64(len(s))); err != nil { | |
| return err | |
| } | |
| _, err := df.rw.WriteString(s) | |
| return err | |
| } | |
| func (df *DataFile) WriteUint16(x uint16) error { | |
| var buf [2]byte | |
| binary.LittleEndian.PutUint16(buf[:], x) | |
| _, err := df.rw.Write(buf[:]) | |
| return err | |
| } | |
| func (df *DataFile) WriteUint32(x uint32) error { | |
| var buf [4]byte | |
| binary.LittleEndian.PutUint32(buf[:], x) | |
| _, err := df.rw.Write(buf[:]) | |
| return err | |
| } | |
| func (df *DataFile) WriteUint64(x uint64) error { | |
| var buf [8]byte | |
| binary.LittleEndian.PutUint64(buf[:], x) | |
| _, err := df.rw.Write(buf[:]) | |
| return err | |
| } | |
| func (df *DataFile) WriteUvarint(x uint64) error { | |
| var buf [10]byte | |
| n := binary.PutUvarint(buf[:], x) | |
| _, err := df.rw.Write(buf[:n]) | |
| return err | |
| } | |
| func (df *DataFile) Available() int { | |
| return df.rw.Available() | |
| } | |
| func (df *DataFile) WriterBuffered() int { | |
| return df.rw.Writer.Buffered() | |
| } | |
| func (df *DataFile) WriterSize() int { | |
| return df.rw.Writer.Size() | |
| } | |
| func (df *DataFile) Peek(n int) ([]byte, error) { | |
| return df.rw.Peek(n) | |
| } | |
| func (df *DataFile) Discard(n int) (int, error) { | |
| return df.rw.Discard(n) | |
| } | |
| func (df *DataFile) Flush() error { | |
| return df.rw.Flush() | |
| } | |
| func (df *DataFile) Sync() error { | |
| err := df.rw.Flush() | |
| if err != nil { | |
| return err | |
| } | |
| return df.file.Sync() | |
| } | |
| func (df *DataFile) Truncate(size int64) error { | |
| err := df.rw.Flush() | |
| if err != nil { | |
| return err | |
| } | |
| err = df.file.Sync() | |
| if err != nil { | |
| return err | |
| } | |
| df.rw = nil | |
| err = df.file.Truncate(size) | |
| if err != nil { | |
| return err | |
| } | |
| r := bufio.NewReaderSize(df.file, blockSZ) | |
| w := bufio.NewWriterSize(df.file, blockSZ) | |
| df.rw = bufio.NewReadWriter(r, w) | |
| return nil | |
| } | |
| func (df *DataFile) Close() error { | |
| err := df.rw.Flush() | |
| if err != nil { | |
| return err | |
| } | |
| err = df.file.Sync() | |
| if err != nil { | |
| return err | |
| } | |
| err = df.file.Close() | |
| if err != nil { | |
| return err | |
| } | |
| return nil | |
| } | |
| func openFile(path string) (*os.File, error) { | |
| var fd *os.File | |
| var err error | |
| if _, err = os.Stat(path); os.IsNotExist(err) { | |
| dir, file := filepath.Split(path) | |
| err = os.MkdirAll(dir, os.ModeDir) | |
| if err != nil { | |
| return nil, err | |
| } | |
| fd, err = os.Create(dir + file) | |
| if err != nil { | |
| return nil, err | |
| } | |
| err = fd.Close() | |
| if err != nil { | |
| return fd, err | |
| } | |
| } | |
| fd, err = os.OpenFile(path, os.O_RDWR|os.O_APPEND, os.ModeSticky) | |
| if err != nil { | |
| return nil, err | |
| } | |
| return fd, nil | |
| } |
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