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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,78 @@ | ||
| package gzip | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "compress/gzip" | ||
| "io" | ||
| ) | ||
|
|
||
| // DefaultBufferSize is the default buffer size used by the Compressor. | ||
| const DefaultBufferSize = 65536 | ||
|
|
||
| // Compressor is a wrapper around a gzip.Writer that reads from an io.Reader | ||
| // and writes to an internal buffer. The internal buffer is used to store | ||
| // compressed data until it is read by the caller. | ||
| type Compressor struct { | ||
| r io.Reader | ||
| bufSz int | ||
| buf *bytes.Buffer | ||
| gzw *gzip.Writer | ||
|
|
||
| nRx int64 | ||
| nTx int64 | ||
| } | ||
|
|
||
| // NewCompressor returns an instantiated Compressor that reads from r and | ||
| // compresses the data using gzip. | ||
| func NewCompressor(r io.Reader, bufSz int) (*Compressor, error) { | ||
| buf := new(bytes.Buffer) | ||
| gzw, err := gzip.NewWriterLevel(buf, gzip.DefaultCompression) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return &Compressor{ | ||
| r: r, | ||
| bufSz: bufSz, | ||
| buf: buf, | ||
| gzw: gzw, | ||
| }, nil | ||
| } | ||
|
|
||
| // Read reads compressed data. | ||
| func (c *Compressor) Read(p []byte) (n int, err error) { | ||
| if c.buf.Len() == 0 && c.gzw != nil { | ||
| nn, err := io.CopyN(c.gzw, c.r, int64(c.bufSz)) | ||
| c.nRx += nn | ||
| c.nTx += int64(len(p)) | ||
| if err != nil { | ||
| // Time to write the footer. | ||
| if err := c.Close(); err != nil { | ||
| return 0, err | ||
| } | ||
| if err != io.EOF { | ||
| // Actual error, let caller handle | ||
| return 0, err | ||
| } | ||
| } else if nn > 0 { | ||
| // We read some data, but didn't hit any error. | ||
| // Just flush the data in the buffer, ready | ||
| // to be read. | ||
| if err := c.gzw.Flush(); err != nil { | ||
| return 0, err | ||
| } | ||
| } | ||
| } | ||
| return c.buf.Read(p) | ||
| } | ||
|
|
||
| // Close closes the Compressor. | ||
| func (c *Compressor) Close() error { | ||
| if c.gzw == nil { | ||
| return nil | ||
| } | ||
| if err := c.gzw.Close(); err != nil { | ||
| return err | ||
| } | ||
| c.gzw = nil | ||
| return nil | ||
| } |
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