Tweaks to decode interface

README.md

@@ -17,6 +17,4 @@ Thanks also to [distri's squashfs library](https://github.com/distr1/distri/tree
 
 ## Performance
 
-This library, decompressing the Firefox AppImage and using go tests, takes about twice as long as `unsquashfs` on my quad core laptop. (~1 second with the library and about half a second with `unsquashfs`).
-
-**My recents tests have shown the Firefox AppImage might be an outlier and this library might be considerably slower (4x ~ 6x time slower then `unsquashfs`)**
+Testing on a zstd compressed file, my library is anywhere from 5x ~ 7x slower then `unsquashfs`

internal/data/fullreader.go

@@ -49,27 +49,26 @@ func (r FullReader) process(index int, offset int64, od *outDat, out chan *outDa
 		od.data = make([]byte, r.blockSize)
 		return
 	}
-	// rdr := io.LimitReader(toreader.NewReader(r.r, offset), int64(size))
 	if size == r.sizes[index] {
-		//Special workaround for zstd for increased performancce.
-		if zstd, ok := r.d.(*decompress.Zstd); ok {
-			od.data = make([]byte, size)
-			_, od.err = r.r.ReadAt(od.data, offset)
-			if od.err == nil {
-				od.data, od.err = zstd.Decode(od.data)
-			}
-		} else {
-			var rdr io.ReadCloser
-			rdr, od.err = r.d.Reader(io.LimitReader(toreader.NewReader(r.r, offset), int64(size)))
+		if dec, ok := r.d.(decompress.Decoder); ok {
+			dat := make([]byte, size)
+			_, od.err = r.r.ReadAt(dat, offset)
 			if od.err != nil {
 				return
 			}
-			od.data = make([]byte, r.blockSize)
-			var read int
-			read, od.err = rdr.Read(od.data)
-			od.data = od.data[:read]
-			rdr.Close()
+			od.data, od.err = dec.Decode(dat, int(r.blockSize))
+			return
 		}
+		var rdr io.ReadCloser
+		rdr, od.err = r.d.Reader(io.LimitReader(toreader.NewReader(r.r, offset), int64(size)))
+		if od.err != nil {
+			return
+		}
+		od.data = make([]byte, r.blockSize)
+		var read int
+		read, od.err = rdr.Read(od.data)
+		od.data = od.data[:read]
+		rdr.Close()
 	} else {
 		od.data = make([]byte, size)
 		_, od.err = r.r.ReadAt(od.data, offset)
@@ -206,40 +205,59 @@ func (r FullReader) WriteTo(w io.Writer) (n int64, err error) {
 		go r.process(i, int64(offset), od, out)
 		offset += uint64(realSize(r.sizes[i]))
 	}
-	var cur int
-	cache := make(map[int]outDat)
-	var tmpN int
-	for dat := range out {
-		if dat.err != nil {
-			err = dat.err
-			pol.Put(dat)
-			return
-		}
-		if dat.i != cur {
-			cache[dat.i] = *dat
-			pol.Put(dat)
-			continue
-		}
-		tmpN, err = w.Write(dat.data)
-		n += int64(tmpN)
-		pol.Put(dat)
-		if err != nil {
-			return
-		}
-		cur++
-		var ok bool
-		var curDat outDat
-		for {
-			curDat, ok = cache[cur]
-			if !ok {
-				break
+	wt, ok := w.(io.WriterAt)
+	if !ok {
+		var cur int
+		cache := make(map[int]outDat)
+		var tmpN int
+		var dat *outDat
+		for cur < len(r.sizes) {
+			dat = <-out
+			defer pol.Put(dat)
+			if dat.err != nil {
+				err = dat.err
+				return
 			}
-			tmpN, err = w.Write(curDat.data)
+			if dat.i != cur {
+				cache[dat.i] = *dat
+				continue
+			}
+			tmpN, err = w.Write(dat.data)
 			n += int64(tmpN)
 			if err != nil {
 				return
 			}
 			cur++
+			var ok bool
+			var curDat outDat
+			for {
+				curDat, ok = cache[cur]
+				if !ok {
+					break
+				}
+				tmpN, err = w.Write(curDat.data)
+				n += int64(tmpN)
+				if err != nil {
+					return
+				}
+				cur++
+			}
+		}
+	} else {
+		var done int
+		var dat *outDat
+		for done < len(r.sizes) {
+			dat = <-out
+			defer pol.Put(dat)
+			if dat.err != nil {
+				err = dat.err
+				return
+			}
+			_, err = wt.WriteAt(dat.data, int64(dat.i*int(r.blockSize)))
+			if err != nil {
+				return
+			}
+			done++
 		}
 	}
 	return

internal/data/reader.go

@@ -53,14 +53,14 @@ func (r *Reader) advance() (err error) {
 		} else {
 			r.cur = io.LimitReader(r.master, int64(size))
 			if size == r.blockSizes[0] {
-				if r.d.Resetable() {
+				if rs, ok := r.d.(decompress.Resetable); ok {
 					if r.comRdr == nil {
 						r.cur, err = r.d.Reader(r.cur)
 						if err != nil {
 							return
 						}
 					} else {
-						err = r.d.Reset(r.comRdr, r.cur)
+						err = rs.Reset(r.comRdr, r.cur)
 						r.cur = r.comRdr
 					}
 				} else {

internal/decompress/gzip.go

@@ -12,8 +12,6 @@ func (g GZip) Reader(src io.Reader) (io.ReadCloser, error) {
 	return zlib.NewReader(src)
 }
 
-func (g GZip) Resetable() bool { return true }
-
 func (g GZip) Reset(old, src io.Reader) error {
 	return old.(zlib.Resetter).Reset(src, nil)
 }

internal/decompress/interface.go

@@ -1,19 +1,22 @@
 package decompress
 
 import (
-	"errors"
 	"io"
 )
 
-var ErrNotResetable = errors.New("decompressor not resetable")
-
 type Decompressor interface {
 	//Creates a new decompressor reading from src.
 	Reader(src io.Reader) (io.ReadCloser, error)
-	//Reports whether Reset will work or not.
-	Resetable() bool
+}
+
+type Resetable interface {
 	//Reset attempts to re-use an old decompressor with new data.
 	//Will return ErrNotResetable if not Resetable().
 	//Must ALWAYS be provided with a reader created with Reader.
 	Reset(old, src io.Reader) error
 }
+
+type Decoder interface {
+	//Decodes a chunk of data all at once.
+	Decode(in []byte, outSize int) ([]byte, error)
+}

internal/decompress/lz4.go

@@ -12,9 +12,16 @@ func (l Lz4) Reader(r io.Reader) (io.ReadCloser, error) {
 	return io.NopCloser(lz4.NewReader(r)), nil
 }
 
-func (l Lz4) Resetable() bool { return true }
-
 func (l Lz4) Reset(old, src io.Reader) error {
 	old.(*lz4.Reader).Reset(src)
 	return nil
 }
+
+func (l Lz4) Decode(in []byte, outSize int) (out []byte, err error) {
+	out = make([]byte, outSize)
+	outLen, err := lz4.UncompressBlock(in, out)
+	if outLen < outSize {
+		out = out[:outLen]
+	}
+	return
+}

internal/decompress/lzma.go

@@ -12,7 +12,3 @@ func (l Lzma) Reader(r io.Reader) (io.ReadCloser, error) {
 	rdr, err := lzma.NewReader(r)
 	return io.NopCloser(rdr), err
 }
-
-func (l Lzma) Resetable() bool { return false }
-
-func (l Lzma) Reset(old, src io.Reader) error { return ErrNotResetable }

internal/decompress/lzo.go

@@ -16,7 +16,3 @@ func (l Lzo) Reader(r io.Reader) (io.ReadCloser, error) {
 	}
 	return io.NopCloser(bytes.NewReader(cache)), nil
 }
-
-func (l Lzo) Resetable() bool { return false }
-
-func (l Lzo) Reset(old, src io.Reader) error { return ErrNotResetable }

internal/decompress/xz.go

@@ -13,8 +13,6 @@ func (x Xz) Reader(r io.Reader) (io.ReadCloser, error) {
 	return io.NopCloser(rdr), err
 }
 
-func (x Xz) Resetable() bool { return true }
-
 func (x Xz) Reset(old, src io.Reader) error {
 	return old.(*xz.Reader).Reset(src)
 }

internal/decompress/zstd.go

@@ -15,15 +15,13 @@ func (z Zstd) Reader(src io.Reader) (io.ReadCloser, error) {
 	return r.IOReadCloser(), err
 }
 
-func (z Zstd) Resetable() bool { return true }
-
 func (z Zstd) Reset(old, src io.Reader) error {
 	return old.(*zstd.Decoder).Reset(src)
 }
 
-func (z *Zstd) Decode(in []byte) (out []byte, err error) {
+func (z Zstd) Decode(in []byte, outSize int) ([]byte, error) {
 	if z.writeToReader == nil {
 		z.writeToReader, _ = zstd.NewReader(nil)
 	}
-	return z.writeToReader.DecodeAll(in, nil)
+	return z.writeToReader.DecodeAll(in, make([]byte, outSize))
 }

internal/metadata/reader.go

@@ -26,7 +26,7 @@ func realSize(siz uint16) uint16 {
 }
 
 func (r *Reader) advance() (err error) {
-	if !r.d.Resetable() {
+	if _, ok := r.d.(decompress.Resetable); !ok {
 		if clr, ok := r.cur.(io.Closer); ok {
 			clr.Close()
 		}
@@ -39,14 +39,14 @@ func (r *Reader) advance() (err error) {
 	size := realSize(raw)
 	r.cur = io.LimitReader(r.master, int64(size))
 	if size == raw {
-		if r.d.Resetable() {
+		if rs, ok := r.d.(decompress.Resetable); ok {
 			if r.comRdr == nil {
 				r.cur, err = r.d.Reader(r.cur)
 				if err != nil {
 					return
 				}
 			} else {
-				err = r.d.Reset(r.comRdr, r.cur)
+				err = rs.Reset(r.comRdr, r.cur)
 				r.cur = r.comRdr
 			}
 		} else {