In the common case, the grow method only needs to reslice the internal
buffer. Making another function call to grow can be expensive when Write
is called very often with small pieces of data (like a byte or rune).
Thus, we add a tryGrowByReslice method that is inlineable so that we can
avoid an extra call in most cases.
name old time/op new time/op delta
WriteByte-4 35.5µs ± 0% 17.4µs ± 1% -51.03% (p=0.000 n=19+20)
WriteRune-4 55.7µs ± 1% 38.7µs ± 1% -30.56% (p=0.000 n=18+19)
BufferNotEmptyWriteRead-4 304µs ± 5% 283µs ± 3% -6.86% (p=0.000 n=19+17)
BufferFullSmallReads-4 87.0µs ± 5% 66.8µs ± 2% -23.26% (p=0.000 n=17+17)
name old speed new speed delta
WriteByte-4 115MB/s ± 0% 235MB/s ± 1% +104.19% (p=0.000 n=19+20)
WriteRune-4 221MB/s ± 1% 318MB/s ± 1% +44.01% (p=0.000 n=18+19)
Fixes#17857
Change-Id: I08dfb10a1c7e001817729dbfcc951bda12fe8814
Reviewed-on: https://go-review.googlesource.com/42813
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Obtaining the actual size of the underlying storage of the buffer can
be very useful in various scenarios. Long running programs which write
and read large amounts of data to buffers might have to recycle
buffers in order to avoid holding onto potentially huge buffers.
For example, a piece of code which buffers a lot of data in a buffer
might need to release the big buffer and start again with a smaller
buffer after it finished processing the huge amount of data.
In cases where pools of bytes.Buffer are used, being able to check the
size of the allocated data can be very useful.
Instead of forking bytes.Buffer or writing new code, we can export the
Cap() method.
Change-Id: I79d4f0a3cff53b9419d82c8122964761e9e38566
Reviewed-on: https://go-review.googlesource.com/8342
Reviewed-by: Rob Pike <r@golang.org>
