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| author | Alberto Donizetti <alb.donizetti@gmail.com> | 2017-03-17 18:42:58 +0100 |
|---|---|---|
| committer | Rob Pike <r@golang.org> | 2017-03-17 20:28:23 +0000 |
| commit | ed00cd94f2cd01f49ee8da8b1dc0c06b66d34b2f (patch) | |
| tree | d2d1e5c9e5bf0203076af26293f706bc680c27e5 | |
| parent | 42e97468a1fd4b9f08bccd076edb1598435c72fb (diff) | |
| download | go-ed00cd94f2cd01f49ee8da8b1dc0c06b66d34b2f.tar.gz go-ed00cd94f2cd01f49ee8da8b1dc0c06b66d34b2f.zip | |
encoding/gob: make integers encoding faster
name old time/op new time/op delta
EncodeInt32Slice-4 14.6µs ± 2% 12.2µs ± 1% -16.65% (p=0.000 n=19+18)
Change-Id: I078a171f1633ff81d7e3f981dc9a398309ecb2c0
Reviewed-on: https://go-review.googlesource.com/38269
Reviewed-by: Rob Pike <r@golang.org>
| -rw-r--r-- | src/encoding/gob/encode.go | 16 | ||||
| -rw-r--r-- | src/encoding/gob/timing_test.go | 2 |
2 files changed, 9 insertions, 9 deletions
diff --git a/src/encoding/gob/encode.go b/src/encoding/gob/encode.go index 50cd6adb46..d67153da90 100644 --- a/src/encoding/gob/encode.go +++ b/src/encoding/gob/encode.go @@ -8,7 +8,9 @@ package gob import ( "encoding" + "encoding/binary" "math" + "math/bits" "reflect" "sync" ) @@ -107,14 +109,12 @@ func (state *encoderState) encodeUint(x uint64) { state.b.WriteByte(uint8(x)) return } - i := uint64Size - for x > 0 { - state.buf[i] = uint8(x) - x >>= 8 - i-- - } - state.buf[i] = uint8(i - uint64Size) // = loop count, negated - state.b.Write(state.buf[i : uint64Size+1]) + + binary.BigEndian.PutUint64(state.buf[1:], x) + bc := bits.LeadingZeros64(x) >> 3 // 8 - bytelen(x) + state.buf[bc] = uint8(bc - uint64Size) // and then we subtract 8 to get -bytelen(x) + + state.b.Write(state.buf[bc : uint64Size+1]) } // encodeInt writes an encoded signed integer to state.w. diff --git a/src/encoding/gob/timing_test.go b/src/encoding/gob/timing_test.go index 424b7e6ea8..a7e7e683cc 100644 --- a/src/encoding/gob/timing_test.go +++ b/src/encoding/gob/timing_test.go @@ -171,7 +171,7 @@ func BenchmarkEncodeInt32Slice(b *testing.B) { enc := NewEncoder(&buf) a := make([]int32, 1000) for i := range a { - a[i] = 1234 + a[i] = int32(i * 100) } b.ResetTimer() for i := 0; i < b.N; i++ { |