• Russ Cox's avatar
    reflect: make Value an opaque struct · a479a455
    Russ Cox authored
    Making Value opaque means we can drop the interface kludges
    in favor of a significantly simpler and faster representation.
    v.Kind() will be a prime candidate for inlining too.
    
    On a Thinkpad X201s using -benchtime 10:
    
    benchmark                           old ns/op    new ns/op    delta
    json.BenchmarkCodeEncoder           284391780    157415960  -44.65%
    json.BenchmarkCodeMarshal           286979140    158992020  -44.60%
    json.BenchmarkCodeDecoder           717175800    388288220  -45.86%
    json.BenchmarkCodeUnmarshal         734470500    404548520  -44.92%
    json.BenchmarkCodeUnmarshalReuse    707172280    385258720  -45.52%
    json.BenchmarkSkipValue              24630036     18557062  -24.66%
    
    benchmark                            old MB/s     new MB/s  speedup
    json.BenchmarkCodeEncoder                6.82        12.33    1.81x
    json.BenchmarkCodeMarshal                6.76        12.20    1.80x
    json.BenchmarkCodeDecoder                2.71         5.00    1.85x
    json.BenchmarkCodeUnmarshal              2.64         4.80    1.82x
    json.BenchmarkCodeUnmarshalReuse         2.74         5.04    1.84x
    json.BenchmarkSkipValue                 77.92       103.42    1.33x
    
    I cannot explain why BenchmarkSkipValue gets faster.
    Maybe it is one of those code alignment things.
    
    R=iant, r, gri, r
    CC=golang-dev
    https://golang.org/cl/5373101
    a479a455
all_test.go 37.1 KB