You don't need to use reflect here. You may well find that something like
this is faster:
func (b *Binlog) writeArgumentToOutput(writer writer, arg
interface{}) error {
var i uint64
switch arg := arg.(type) {
case uintptr:
i = uint64(arg)
case int:
i = uint64(arg)
case int8:
i = uint64(arg)
case int16:
i = uint64(arg)
case int32:
i = uint64(arg)
case int64:
i = uint64(arg)
case uint8:
i = uint64(arg)
case uint16:
i = uint64(arg)
case uint32:
i = uint64(arg)
case uint64:
i = arg
default:
return fmt.Errorf("Unsupported type: %T\n",
reflect.TypeOf(arg))
}
return writer.write(b.ioWriter, &i)
}
There are a couple of issues I'd point out with the original code:
- just because a value has a given Kind (e.g. reflect.Int16) does not mean
it can be converted to that type, because it may be some other named type
with an int16 underlying type. A better (and shorter, but probably no
faster) way to do it would be something like:
https://play.golang.org/p/jhpbaaDoY57
- it seems odd that you're passing an unsafe.Pointer to the write method.
How is that method supposed to know how many bytes to write?
On Sun, 25 Nov 2018 at 16:09, <lary...@gmail.com> wrote:
> The code below consumes ~40% of the total execution time. According to
> the profiler i := uint64(arg.(uint32)) is a major contributor
>
> // Cast the integer argument to uint64 and call a "writer"
> // The "writer" knows how many bytes to add to the binary stream
> // Type casts from interface{} to integer consume 40% of the overall
> // time. Can I do better? What is interface{} in Golang?
> func (b *Binlog) writeArgumentToOutput(writer writer, arg interface{},
> argKind reflect.Kind) error {
> // unsafe pointer to the data depends on the data type
> var err error
> switch argKind {
> case reflect.Int8:
> i := uint64(arg.(int8))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Int16:
> i := uint64(arg.(int16))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Int32:
> i := uint64(arg.(int32))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Int64:
> i := uint64(arg.(int64))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Uint8:
> i := uint64(arg.(uint8))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Uint16:
> i := uint64(arg.(uint16))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Uint32:
> i := uint64(arg.(uint32))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Uint64:
> i := uint64(arg.(uint64))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Int:
> i := uint64(arg.(int))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> case reflect.Uint:
> i := uint64(arg.(uint))
> err = writer.write(b.ioWriter, unsafe.Pointer(&i))
> default:
> return fmt.Errorf("Unsupported type: %T\n", reflect.TypeOf(arg))
> }
> return err
> }
>
>
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