pool writers (indexed by compression level, since that can't be reset)

groot/internal/rcompress/rcompress.go

@@ -207,17 +207,17 @@ func compressBlock(alg Kind, lvl int, tgt, src []byte) (int, error) {
 		hdr[0] = 'Z'
 		hdr[1] = 'L'
 		hdr[2] = 8 // zlib deflated
-		w, err := zlib.NewWriterLevel(buf, lvl)
+		w, err := zlibGetWriterLevel(buf, lvl)
 		if err != nil {
 			return 0, fmt.Errorf("rcompress: could not create ZLIB compressor: %w", err)
 		}
 
 		_, err = w.Write(src)
 		if err != nil {
-			_ = w.Close()
+			_ = zlibPutWriterLevel(w, lvl)
 			return 0, fmt.Errorf("rcompress: could not write ZLIB compressed bytes: %w", err)
 		}
-		err = w.Close()
+		err = zlibPutWriterLevel(w, lvl)
 		switch {
 		case err == nil:
 			// ok.
@@ -269,7 +269,7 @@ func compressBlock(alg Kind, lvl int, tgt, src []byte) (int, error) {
 
 		const chksum = 8
 		var room = int(float64(srcsz) * 2e-4) // lz4 needs some extra scratch space
-		dst := make([]byte, HeaderSize+chksum+len(src)+room)
+		dst := lz4GetBuffer(HeaderSize + chksum + len(src) + room)
 		wrk := dst[HeaderSize:]
 		var n int
 		switch {
@@ -284,18 +284,21 @@ func compressBlock(alg Kind, lvl int, tgt, src []byte) (int, error) {
 			n, err = lz4.CompressBlock(src, wrk[chksum:], ht)
 		}
 		if err != nil {
+			lz4PutBuffer(dst)
 			return 0, fmt.Errorf("rcompress: could not compress with LZ4: %w", err)
 		}
 
 		if n == 0 {
 			// not compressible.
+			lz4PutBuffer(dst)
 			return len(src), errNoCompression
 		}
 
 		wrk = wrk[:n+chksum]
 		binary.BigEndian.PutUint64(wrk[:chksum], xxHash64.Checksum(wrk[chksum:], 0))
 		dstsz = int32(n + chksum)
 		n = copy(buf.p, wrk)
+		lz4PutBuffer(dst)
 		buf.c += n
 
 	case ZSTD:
@@ -377,17 +380,16 @@ func Decompress(dst []byte, src io.Reader) error {
 				return fmt.Errorf("rcompress: could not create ZLIB reader: %w", err)
 			}
 			_, err = io.ReadFull(rc, dst[beg:end])
-			rc.Close()
-			zlibReaderPool.Put(rc)
+			zlibPutReader(rc)
 			if err != nil {
 				return fmt.Errorf("rcompress: could not decompress ZLIB buffer: %w", err)
 			}
 
 		case LZ4:
-			src := lz4NewBuffer(srcsz)
+			src := lz4GetBuffer(int(srcsz))
 			_, err = io.ReadFull(lr, src)
 			if err != nil {
-				lz4BufferPool.Put(src)
+				lz4PutBuffer(src)
 				return fmt.Errorf("rcompress: could not read LZ4 block: %w", err)
 			}
 			const chksum = 8
@@ -398,9 +400,9 @@ func Decompress(dst []byte, src io.Reader) error {
 				case srcsz > tgtsz:
 					// no compression
 					copy(dst[beg:end], src[chksum:])
-					lz4BufferPool.Put(src)
+					lz4PutBuffer(src)
 				default:
-					lz4BufferPool.Put(src)
+					lz4PutBuffer(src)
 					return fmt.Errorf("rcompress: could not decompress LZ4 block: %w", err)
 				}
 			}
@@ -423,13 +425,12 @@ func Decompress(dst []byte, src io.Reader) error {
 			}
 
 		case ZSTD:
-			rc, err := zstdNewReader(lr)
+			rc, err := zstdGetReader(lr)
 			if err != nil {
 				return fmt.Errorf("rcompress: could not create ZSTD reader: %w", err)
 			}
 			_, err = io.ReadFull(rc, dst[beg:end])
-			rc.Reset(nil)
-			zstdReaderPool.Put(rc)
+			zstdPutReader(rc)
 			if err != nil {
 				return fmt.Errorf("rcompress: could not decompress ZSTD block: %w", err)
 			}
@@ -464,24 +465,29 @@ var (
 	_ io.Writer = (*wbuff)(nil)
 )
 
-// TODO writers, need to index by options (e.g. compression level)
 var (
-	lz4BufferPool  = sync.Pool{}
-	zlibReaderPool = sync.Pool{}
-	zstdReaderPool = sync.Pool{}
+	lz4BufferPool   sync.Pool
+	zlibReaderPool  sync.Pool
+	zstdReaderPool  sync.Pool
+	zlibWriterPools sync.Map // map[lvl]*pool
+	zstdWriterPools sync.Map // map[lvl]*pool
 )
 
-func lz4NewBuffer(size int64) []byte {
+func lz4GetBuffer(size int) []byte {
 	var b []byte
 	if bi := lz4BufferPool.Get(); bi != nil {
 		b = bi.([]byte)
 	}
-	if int64(cap(b)) >= size {
+	if cap(b) >= size {
 		return b[:size]
 	}
 	return make([]byte, size)
 }
 
+func lz4PutBuffer(b []byte) {
+	lz4BufferPool.Put(b)
+}
+
 func zlibNewReader(r io.Reader) (io.ReadCloser, error) {
 	if ri := zlibReaderPool.Get(); ri != nil {
 		ri.(zlib.Resetter).Reset(r, nil)
@@ -490,11 +496,68 @@ func zlibNewReader(r io.Reader) (io.ReadCloser, error) {
 	return zlib.NewReader(r)
 }
 
-func zstdNewReader(r io.Reader) (*zstd.Decoder, error) {
+func zlibPutReader(r io.ReadCloser) error {
+	// Note that zlib readers should be closed (but not reset)
+	err := r.Close()
+	zlibReaderPool.Put(r)
+	return err
+}
+
+func zstdGetReader(r io.Reader) (*zstd.Decoder, error) {
 	if ri := zstdReaderPool.Get(); ri != nil {
 		rd := ri.(*zstd.Decoder)
 		rd.Reset(r)
 		return rd, nil
 	}
 	return zstd.NewReader(r)
 }
+
+func zstdPutReader(r *zstd.Decoder) {
+	// Note that zstd decoders should be reset (but not closed)
+	r.Reset(nil)
+	zstdReaderPool.Put(r)
+}
+
+func zlibGetWriterLevel(w io.Writer, lvl int) (*zlib.Writer, error) {
+	if pi, ok := zlibWriterPools.Load(lvl); ok {
+		if wi := pi.(*sync.Pool).Get(); wi != nil {
+			z := wi.(*zlib.Writer)
+			z.Reset(w)
+			return z, nil
+		}
+	}
+	return zlib.NewWriterLevel(w, lvl)
+}
+
+func zlibPutWriterLevel(w *zlib.Writer, lvl int) error {
+	err := w.Close()
+	if pi, ok := zlibWriterPools.Load(lvl); ok {
+		pi.(*sync.Pool).Put(w)
+	} else {
+		pi, _ = zlibWriterPools.LoadOrStore(lvl, new(sync.Pool))
+		pi.(*sync.Pool).Put(w)
+	}
+	return err
+}
+
+func zstdGetWriterLevel(w io.Writer, lvl int) (*zstd.Encoder, error) {
+	if pi, ok := zstdWriterPools.Load(lvl); ok {
+		if wi := pi.(*sync.Pool).Get(); wi != nil {
+			z := wi.(*zstd.Encoder)
+			z.Reset(w)
+			return z, nil
+		}
+	}
+	return zstd.NewWriter(w, zstd.WithEncoderLevel(zstd.EncoderLevel(lvl)))
+}
+
+func zstdPutWriterLevel(w *zstd.Encoder, lvl int) error {
+	err := w.Close()
+	if pi, ok := zstdWriterPools.Load(lvl); ok {
+		pi.(*sync.Pool).Put(w)
+	} else {
+		pi, _ = zstdWriterPools.LoadOrStore(lvl, new(sync.Pool))
+		pi.(*sync.Pool).Put(w)
+	}
+	return err
+}