diff options
| -rw-r--r-- | internal/zlib/reader.go | 19 | ||||
| -rw-r--r-- | internal/zlib/writer.go | 46 |
2 files changed, 50 insertions, 15 deletions
diff --git a/internal/zlib/reader.go b/internal/zlib/reader.go index 5141b2f6..2234e7e0 100644 --- a/internal/zlib/reader.go +++ b/internal/zlib/reader.go @@ -7,13 +7,14 @@ Package zlib implements reading and writing of zlib format compressed data, as specified in RFC 1950. This package differs from the standard library's compress/zlib package -in that it pools readers to reduce allocations. Writers are unchanged. +in that it pools readers and writers to reduce allocations. -Note that closing the reader causes it to be returned to a pool for -reuse. Therefore, the caller must not retain references to the -reader after closing it; in the standard library's compress/zlib package, -it is legal to Reset a closed reader and continue using it; that is -not allowed here, so there is simply no Resetter interface. +Note that closing a reader or writer causes it to be returned to a pool +for reuse. Therefore, the caller must not retain references to a +reader or writer after closing it; in the standard library's +compress/zlib package, it is legal to Reset a closed reader or writer +and continue using it; that is not allowed here, so there is simply no +Resetter interface. The implementation provides filters that uncompress during reading and compress during writing. For example, to write compressed data @@ -58,7 +59,7 @@ var ( ErrHeader = errors.New("zlib: invalid header") ) -var pool = sync.Pool{ +var readerPool = sync.Pool{ New: func() any { r := new(reader) return r @@ -86,7 +87,7 @@ func NewReader(r io.Reader) (io.ReadCloser, error) { // NewReaderDict ignores the dictionary if the compressed data does not refer to it. // If the compressed data refers to a different dictionary, NewReaderDict returns [ErrDictionary]. func NewReaderDict(r io.Reader, dict []byte) (io.ReadCloser, error) { - v := pool.Get() + v := readerPool.Get() z, ok := v.(*reader) if !ok { panic("zlib: pool returned unexpected type") @@ -140,7 +141,7 @@ func (z *reader) Close() error { return z.err } - pool.Put(z) + readerPool.Put(z) return nil } diff --git a/internal/zlib/writer.go b/internal/zlib/writer.go index 14eca474..81c57f55 100644 --- a/internal/zlib/writer.go +++ b/internal/zlib/writer.go @@ -10,6 +10,7 @@ import ( "fmt" "hash" "io" + "sync" "codeberg.org/lindenii/furgit/internal/adler32" ) @@ -37,6 +38,12 @@ type Writer struct { wroteHeader bool } +var writerPool = sync.Pool{ + New: func() any { + return new(Writer) + }, +} + // NewWriter creates a new [Writer]. // Writes to the returned Writer are compressed and written to w. // @@ -66,11 +73,33 @@ func NewWriterLevelDict(w io.Writer, level int, dict []byte) (*Writer, error) { if level < HuffmanOnly || level > BestCompression { return nil, fmt.Errorf("zlib: invalid compression level: %d", level) } - return &Writer{ - w: w, - level: level, - dict: dict, - }, nil + v := writerPool.Get() + z, ok := v.(*Writer) + if !ok { + panic("zlib: pool returned unexpected type") + } + + // flate.Writer can only be Reset with the same level/dictionary mode. + // Reuse it only when the configuration is unchanged and dictionary-free. + reuseCompressor := z.compressor != nil && z.level == level && z.dict == nil && dict == nil + if !reuseCompressor { + z.compressor = nil + } + if z.digest != nil { + z.digest.Reset() + } + + *z = Writer{ + w: w, + level: level, + dict: dict, + compressor: z.compressor, + digest: z.digest, + } + if z.compressor != nil { + z.compressor.Reset(w) + } + return z, nil } // Reset clears the state of the [Writer] z such that it is equivalent to its @@ -190,5 +219,10 @@ func (z *Writer) Close() error { // ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952). binary.BigEndian.PutUint32(z.scratch[:], checksum) _, z.err = z.w.Write(z.scratch[0:4]) - return z.err + if z.err != nil { + return z.err + } + + writerPool.Put(z) + return nil } |