[Libguestfs] [PATCH libnbd v2 7/9] golang: aio_buffer.go: Speed up FromBytes()

[Nir Soffer]

Using Slice() we can use builtin copy() instead of a manual loop, which
is 4.6 times faster with a typical 256k buffer:

Before:
BenchmarkFromBytes-12            	    9806	    111474 ns/op

After:
BenchmarkFromBytes-12            	   48193	     24106 ns/op

Signed-off-by: Nir Soffer <nsoffer at redhat.com>
---
 golang/aio_buffer.go | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/golang/aio_buffer.go b/golang/aio_buffer.go
index 008d9ae0..52ea54de 100644
--- a/golang/aio_buffer.go
+++ b/golang/aio_buffer.go
@@ -47,25 +47,22 @@ func MakeAioBuffer(size uint) AioBuffer {
 
 // MakeAioBuffer makes a new buffer backed by a C allocated array. The
 // underlying buffer is set to zero.
 func MakeAioBufferZero(size uint) AioBuffer {
 	return AioBuffer{C.calloc(C.ulong(1), C.ulong(size)), size}
 }
 
 // FromBytes makes a new buffer backed by a C allocated array, initialized by
 // copying the given Go slice.
 func FromBytes(buf []byte) AioBuffer {
-	size := len(buf)
-	ret := MakeAioBuffer(uint(size))
-	for i := 0; i < len(buf); i++ {
-		*ret.Get(uint(i)) = buf[i]
-	}
+	ret := MakeAioBuffer(uint(len(buf)))
+	copy(ret.Slice(), buf)
 	return ret
 }
 
 // Free deallocates the underlying C allocated array. Using the buffer after
 // Free() will panic.
 func (b *AioBuffer) Free() {
 	if b.P != nil {
 		C.free(b.P)
 		b.P = nil
 	}
-- 
2.34.1