github.com/leeychee/mlayout

Golang type's memory layout

Package mlayout try to describe golang type's memory layout, especially struct's. According to language's implements, different order of fields use different memory layout, so different memory use ratio sometimes.

Here is a simple example, two structs with different fields order.

type t1 struct {
	a bool
	b int
	c bool
}

type t2 struct {
	a bool
	b bool
	c int
}

fmt.Printf("t1:\n%s\n", mlayout.Layoutof(t1{}))
fmt.Printf("t2:\n%s", mlayout.Layoutof(t2{}))
// Output:
// t1:
// x_______
// xxxxxxxx
// x_______
// t2:
// xx______
// xxxxxxxx

So we could try to imporve the struct's use ratio of memory with this, by adjusting struct's fields order.

Installation

go get -u github.com/leeychee/mlayout

Usage

For now, you can use the lib to get a type's use ratio of memory, and ascii image.

type t1 struct {
	a bool
	b int
	c bool
}
l := mlayout.Layoutof(t1{})
fmt.Printf("t1's use ratio is %.2f", l.UseRatio())
fmt.Printf("t1's acsii image is: \n%s\n", l)

TODO

Maybe, we could build a cmd tool to analysis structs, and give some advices.