$ go get gitlab.com/zyfran/sizeof
// main.go
package main
type (
myStruct struct {
myBool bool // 1 byte
myFloat float64 // 8 bytes
myInt int32 // 4 bytes
Int int16 // 2 bytes
}
myStructOptimized1 struct {
myFloat float64 // 8 bytes
myInt int32 // 4 bytes
Int int16 // 2 bytes
myBool bool // 1 byte
}
myStructOptimized2 struct {
myFloat float64 // 8 bytes
myInt int32 // 4 bytes
myBool bool // 1 byte
Int int16 // 2 bytes
}
)
func main() {
// do something
}// main_test.go
package main
import (
"testing"
"gitlab.com/zyfran/sizeof"
)
func TestStructures(t *testing.T) {
items := [...]interface{}{
myStruct{},
myStructOptimized1{},
myStructOptimized2{},
}
for _, item := range items {
if currentSize, optimalSize := sizeof.CheckStruct(item); currentSize != optimalSize {
t.Errorf(
"%sStructure can be optimized from %d to %d bytes",
sizeof.VisualizeStruct(item),
currentSize,
optimalSize,
)
}
}
}Check structures for 64-bit OS
$ GOOS=linux GOARCH=amd64 go test -v
--- FAIL: TestStructures (0.00s)
main_test.go:18:
sizeof(main.myStruct)=24 with alignment=8
myBool bool [x][ ][ ][ ][ ][ ][ ][ ]
myFloat float64 [x][x][x][x][x][x][x][x]
myInt int32 [x][x][x][x]
Int int16 [x][x][ ][ ]
Structure can be optimized from 24 to 16 bytes
Check structures for 32-bit OS
$ GOOS=linux GOARCH=386 go test -v
=== RUN TestStructures
--- FAIL: TestStructures (0.00s)
main_test.go:18:
sizeof(main.myStruct)=20 with alignment=4
myBool bool [x][ ][ ][ ]
myFloat float64 [x][x][x][x]
[x][x][x][x]
myInt int32 [x][x][x][x]
Int int16 [x][x][ ][ ]
Structure can be optimized from 20 to 16 bytes