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Avoid heap allocating scratch buffer in compressio simple reader and writer.

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The 4-byte scratch buffer variables in SimpleWriter.Write and SimpleReader.Read
were being moved to heap because they were being passed into interface methods.

Add a scratch buffer field to SimpleWriter and SimpleReader and use that.

PiperOrigin-RevId: 669036236
This commit is contained in:
Ayush Ranjan
2024-08-29 13:10:48 -07:00
committed by gVisor bot
parent 2511e2e937
commit 431d29921f
1 changed files with 14 additions and 12 deletions
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pkg/compressio/nocompressio.go
+14 -12
View File
@@ -62,6 +62,9 @@ type SimpleReader struct {
// current chunk position
done uint32
// scratch is a 4-byte scratch buffer used for 32-bit integers.
scratch [4]byte
}
var _ io.Reader = (*SimpleReader)(nil)
@@ -88,19 +91,17 @@ func NewSimpleReader(in io.Reader, key []byte) (*SimpleReader, error) {
// Read implements io.Reader.Read.
func (r *SimpleReader) Read(p []byte) (int, error) {
var scratch [4]byte
if len(p) == 0 {
return r.in.Read(p)
}
// need next chunk?
if r.done >= r.chunkSize {
if _, err := io.ReadFull(r.in, scratch[:]); err != nil {
if _, err := io.ReadFull(r.in, r.scratch[:]); err != nil {
return 0, err
}
r.chunkSize = binary.BigEndian.Uint32(scratch[:])
r.chunkSize = binary.BigEndian.Uint32(r.scratch[:])
r.done = 0
if r.key != nil {
r.h.Reset()
@@ -136,8 +137,8 @@ func (r *SimpleReader) Read(p []byte) (int, error) {
r.done += uint32(n)
if r.done >= r.chunkSize {
if r.key != nil {
binary.BigEndian.PutUint32(scratch[:], r.chunkSize)
r.h.Write(scratch[:4])
binary.BigEndian.PutUint32(r.scratch[:], r.chunkSize)
r.h.Write(r.scratch[:])
sum := r.h.Sum(nil)
readerSum := make([]byte, len(sum))
@@ -173,6 +174,9 @@ type SimpleWriter struct {
// closed indicates whether the file has been closed.
closed bool
// scratch is a 4-byte scratch buffer used for 32-bit integers.
scratch [4]byte
}
var _ io.Writer = (*SimpleWriter)(nil)
@@ -191,8 +195,6 @@ func NewSimpleWriter(out io.Writer, key []byte) (*SimpleWriter, error) {
// Write implements io.Writer.Write.
func (w *SimpleWriter) Write(p []byte) (int, error) {
var scratch [4]byte
// Did we close already?
if w.closed {
return 0, io.ErrUnexpectedEOF
@@ -201,8 +203,8 @@ func (w *SimpleWriter) Write(p []byte) (int, error) {
l := uint32(len(p))
// chunk length
binary.BigEndian.PutUint32(scratch[:], l)
if _, err := w.out.Write(scratch[:4]); err != nil {
binary.BigEndian.PutUint32(w.scratch[:], l)
if _, err := w.out.Write(w.scratch[:]); err != nil {
return 0, err
}
@@ -219,8 +221,8 @@ func (w *SimpleWriter) Write(p []byte) (int, error) {
_, _ = h.Write(p)
// chunk length
binary.BigEndian.PutUint32(scratch[:], l)
h.Write(scratch[:4])
binary.BigEndian.PutUint32(w.scratch[:], l)
h.Write(w.scratch[:])
sum := h.Sum(nil)
if _, err := io.CopyN(w.out, bytes.NewReader(sum), int64(len(sum))); err != nil {