diff options
Diffstat (limited to 'vendor/github.com/pierrec/lz4/v4/writer.go')
| -rw-r--r-- | vendor/github.com/pierrec/lz4/v4/writer.go | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/vendor/github.com/pierrec/lz4/v4/writer.go b/vendor/github.com/pierrec/lz4/v4/writer.go new file mode 100644 index 0000000000..44a43d251b --- /dev/null +++ b/vendor/github.com/pierrec/lz4/v4/writer.go @@ -0,0 +1,233 @@ +package lz4 + +import ( + "io" + + "github.com/pierrec/lz4/v4/internal/lz4block" + "github.com/pierrec/lz4/v4/internal/lz4errors" + "github.com/pierrec/lz4/v4/internal/lz4stream" +) + +var writerStates = []aState{ + noState: newState, + newState: writeState, + writeState: closedState, + closedState: newState, + errorState: newState, +} + +// NewWriter returns a new LZ4 frame encoder. +func NewWriter(w io.Writer) *Writer { + zw := &Writer{frame: lz4stream.NewFrame()} + zw.state.init(writerStates) + _ = zw.Apply(DefaultBlockSizeOption, DefaultChecksumOption, DefaultConcurrency, defaultOnBlockDone) + zw.Reset(w) + return zw +} + +// Writer allows writing an LZ4 stream. +type Writer struct { + state _State + src io.Writer // destination writer + level lz4block.CompressionLevel // how hard to try + num int // concurrency level + frame *lz4stream.Frame // frame being built + data []byte // pending data + idx int // size of pending data + handler func(int) + legacy bool +} + +func (*Writer) private() {} + +func (w *Writer) Apply(options ...Option) (err error) { + defer w.state.check(&err) + switch w.state.state { + case newState: + case errorState: + return w.state.err + default: + return lz4errors.ErrOptionClosedOrError + } + for _, o := range options { + if err = o(w); err != nil { + return + } + } + w.Reset(w.src) + return +} + +func (w *Writer) isNotConcurrent() bool { + return w.num == 1 +} + +// init sets up the Writer when in newState. It does not change the Writer state. +func (w *Writer) init() error { + w.frame.InitW(w.src, w.num, w.legacy) + if true || !w.isNotConcurrent() { + size := w.frame.Descriptor.Flags.BlockSizeIndex() + w.data = size.Get() + } + w.idx = 0 + return w.frame.Descriptor.Write(w.frame, w.src) +} + +func (w *Writer) Write(buf []byte) (n int, err error) { + defer w.state.check(&err) + switch w.state.state { + case writeState: + case closedState, errorState: + return 0, w.state.err + case newState: + if err = w.init(); w.state.next(err) { + return + } + default: + return 0, w.state.fail() + } + + zn := len(w.data) + for len(buf) > 0 { + if w.idx == 0 && len(buf) >= zn { + // Avoid a copy as there is enough data for a block. + if err = w.write(buf[:zn], false); err != nil { + return + } + n += zn + buf = buf[zn:] + continue + } + // Accumulate the data to be compressed. + m := copy(w.data[w.idx:], buf) + n += m + w.idx += m + buf = buf[m:] + + if w.idx < len(w.data) { + // Buffer not filled. + return + } + + // Buffer full. + if err = w.write(w.data, true); err != nil { + return + } + if !w.isNotConcurrent() { + size := w.frame.Descriptor.Flags.BlockSizeIndex() + w.data = size.Get() + } + w.idx = 0 + } + return +} + +func (w *Writer) write(data []byte, safe bool) error { + if w.isNotConcurrent() { + block := w.frame.Blocks.Block + err := block.Compress(w.frame, data, w.level).Write(w.frame, w.src) + w.handler(len(block.Data)) + return err + } + c := make(chan *lz4stream.FrameDataBlock) + w.frame.Blocks.Blocks <- c + go func(c chan *lz4stream.FrameDataBlock, data []byte, safe bool) { + b := lz4stream.NewFrameDataBlock(w.frame) + c <- b.Compress(w.frame, data, w.level) + <-c + w.handler(len(b.Data)) + b.Close(w.frame) + if safe { + // safe to put it back as the last usage of it was FrameDataBlock.Write() called before c is closed + lz4block.Put(data) + } + }(c, data, safe) + + return nil +} + +// Close closes the Writer, flushing any unwritten data to the underlying io.Writer, +// but does not close the underlying io.Writer. +func (w *Writer) Close() (err error) { + switch w.state.state { + case writeState: + case errorState: + return w.state.err + default: + return nil + } + defer w.state.nextd(&err) + if w.idx > 0 { + // Flush pending data, disable w.data freeing as it is done later on. + if err = w.write(w.data[:w.idx], false); err != nil { + return err + } + w.idx = 0 + } + err = w.frame.CloseW(w.src, w.num) + // It is now safe to free the buffer. + if w.data != nil { + lz4block.Put(w.data) + w.data = nil + } + return +} + +// Reset clears the state of the Writer w such that it is equivalent to its +// initial state from NewWriter, but instead writing to writer. +// Reset keeps the previous options unless overwritten by the supplied ones. +// No access to writer is performed. +// +// w.Close must be called before Reset or pending data may be dropped. +func (w *Writer) Reset(writer io.Writer) { + w.frame.Reset(w.num) + w.state.reset() + w.src = writer +} + +// ReadFrom efficiently reads from r and compressed into the Writer destination. +func (w *Writer) ReadFrom(r io.Reader) (n int64, err error) { + switch w.state.state { + case closedState, errorState: + return 0, w.state.err + case newState: + if err = w.init(); w.state.next(err) { + return + } + default: + return 0, w.state.fail() + } + defer w.state.check(&err) + + size := w.frame.Descriptor.Flags.BlockSizeIndex() + var done bool + var rn int + data := size.Get() + if w.isNotConcurrent() { + // Keep the same buffer for the whole process. + defer lz4block.Put(data) + } + for !done { + rn, err = io.ReadFull(r, data) + switch err { + case nil: + case io.EOF, io.ErrUnexpectedEOF: // read may be partial + done = true + default: + return + } + n += int64(rn) + err = w.write(data[:rn], true) + if err != nil { + return + } + w.handler(rn) + if !done && !w.isNotConcurrent() { + // The buffer will be returned automatically by go routines (safe=true) + // so get a new one fo the next round. + data = size.Get() + } + } + err = w.Close() + return +} |