tree ef913405895f4e11c2612db127a195ff7c545e4c
parent a8b7006b7b0bc10a42b142cbfdebfd29a3fa53ba
author Bryan Matsuo <bryan.matsuo@gmail.com> 1456464980 -0800
committer Bryan Matsuo <bryan.matsuo@gmail.com> 1456465717 -0800

optimize internal parsing function -- avoid unsafe []byte parsing

Making xtob take two byte arguments avoids a lot of slicing.  This makes
the Parse function faster.  In addition, because so much slicing is
avoiding, duplicating the parse logic to ParseBytes resulted in the
function being faster than Parse (<1ns).

The BenchmarkParseBytesNative function has been removed (parseBytes was
identical to ParseBytes).  And a new benchmark,
BenchmarkParseBytesUnsafe, has been added to benchmark the old way of
parsing []byte (which is slightly slower than Parse and thus the new
ParseBytes implementation).

    benchmark                         old ns/op     new ns/op     delta
    BenchmarkUUID_MarshalJSON-4       685           667           -2.63%
    BenchmarkUUID_UnmarshalJSON-4     1145          1162          +1.48%
    BenchmarkParse-4                  61.6          56.5          -8.28%
    BenchmarkParseBytes-4             65.7          55.9          -14.92%
    BenchmarkParseBytesCopy-4         121           115           -4.96%
    BenchmarkNew-4                    1665          1643          -1.32%
    BenchmarkUUID_String-4            112           113           +0.89%
    BenchmarkUUID_URN-4               117           119           +1.71%

    benchmark                         old allocs     new allocs     delta
    BenchmarkUUID_MarshalJSON-4       4              4              +0.00%
    BenchmarkUUID_UnmarshalJSON-4     2              2              +0.00%
    BenchmarkParse-4                  0              0              +0.00%
    BenchmarkParseBytes-4             0              0              +0.00%
    BenchmarkParseBytesCopy-4         1              1              +0.00%
    BenchmarkNew-4                    1              1              +0.00%
    BenchmarkUUID_String-4            1              1              +0.00%
    BenchmarkUUID_URN-4               1              1              +0.00%

    benchmark                         old bytes     new bytes     delta
    BenchmarkUUID_MarshalJSON-4       248           248           +0.00%
    BenchmarkUUID_UnmarshalJSON-4     248           248           +0.00%
    BenchmarkParse-4                  0             0             +0.00%
    BenchmarkParseBytes-4             0             0             +0.00%
    BenchmarkParseBytesCopy-4         48            48            +0.00%
    BenchmarkNew-4                    16            16            +0.00%
    BenchmarkUUID_String-4            48            48            +0.00%
    BenchmarkUUID_URN-4               48            48            +0.00%