From e29a02239eb27d4fe03e04f9fbdbc46e1655bf95 Mon Sep 17 00:00:00 2001 From: Ian Gudger Date: Tue, 21 Aug 2018 16:25:00 -0700 Subject: binary: append slices A new optimization in Go 1.11 improves the efficiency of slice extension: "The compiler now optimizes slice extension of the form append(s, make([]T, n)...)." https://tip.golang.org/doc/go1.11#performance-compiler Before: BenchmarkMarshalUnmarshal-12 2000000 664 ns/op 0 B/op 0 allocs/op BenchmarkReadWrite-12 500000 2395 ns/op 304 B/op 24 allocs/op After: BenchmarkMarshalUnmarshal-12 2000000 628 ns/op 0 B/op 0 allocs/op BenchmarkReadWrite-12 500000 2411 ns/op 304 B/op 24 allocs/op BenchmarkMarshalUnmarshal benchmarks the code in this package, BenchmarkReadWrite benchmarks the code in the standard library. PiperOrigin-RevId: 209679979 Change-Id: I51c6302e53f60bf79f84576b1ead4d36658897cb --- pkg/binary/binary.go | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/pkg/binary/binary.go b/pkg/binary/binary.go index df421bdb6..3b18a86ee 100644 --- a/pkg/binary/binary.go +++ b/pkg/binary/binary.go @@ -35,21 +35,21 @@ var BigEndian = binary.BigEndian // AppendUint16 appends the binary representation of a uint16 to buf. func AppendUint16(buf []byte, order binary.ByteOrder, num uint16) []byte { - buf = extendZero(2, buf) + buf = append(buf, make([]byte, 2)...) order.PutUint16(buf[len(buf)-2:], num) return buf } // AppendUint32 appends the binary representation of a uint32 to buf. func AppendUint32(buf []byte, order binary.ByteOrder, num uint32) []byte { - buf = extendZero(4, buf) + buf = append(buf, make([]byte, 4)...) order.PutUint32(buf[len(buf)-4:], num) return buf } // AppendUint64 appends the binary representation of a uint64 to buf. func AppendUint64(buf []byte, order binary.ByteOrder, num uint64) []byte { - buf = extendZero(8, buf) + buf = append(buf, make([]byte, 8)...) order.PutUint64(buf[len(buf)-8:], num) return buf } @@ -204,13 +204,6 @@ func sizeof(data reflect.Value) uintptr { } } -func extendZero(amount uintptr, buf []byte) []byte { - for i := uintptr(0); i < amount; i++ { - buf = append(buf, 0) - } - return buf -} - // ReadUint16 reads a uint16 from r. func ReadUint16(r io.Reader, order binary.ByteOrder) (uint16, error) { buf := make([]byte, 2) -- cgit v1.2.3