README
¶
SOA - Structure of Arrays
Allocate, Grow, Pack or Unpack Golang slices of basic types to optimize memory access for Data-Driven design. The primary motivation is easier manipulation with packed SIMD instructions like SSE2.
Freatures
- Allocate a new slice of a given basic type which uses one page of memory.
- Grow a slice of a given basic type to the next multiple of a page size.
- Pack all non-zero (0) values of a slice without changing the order.
- Unpack the values of a slice to the next multiple of a page.
Installation
go get -u github.com/andygeiss/soa
Usage
Allocate
The following function creates new entities with a position (p) and velocity (v), which fits into one page size (ex. 4096 bytes on linux).
func createEntities() (p, v []int32) {
p = soa.DefaultManager.Allocate([]int32{}).([]int32)
v = soa.DefaultManager.Allocate([]int32{}).([]int32)
return
}
Grow
Next we want to ensure that we have enough space to add a new entity to the world, by using the following code.
func ensureSpace(offset, p, v) (pn []int32, vn []int32) {
// no more space left for a new entity? then grow ...
if offset + 1 >= len(p) {
pn = soa.DefaultManager.Grow(p)
vn = soa.DefaultManager.Grow(v)
}
return p, v
}
Pack
For serialization we dont need to save unused / initialized zero values. Thus, we pack the slices.
type World struct {
p []int32
v []int32
}
func saveWorld(w *World, filename string) (err error) {
// open a new file
file, err := os.OpenFile(filename, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
if err != nil {
return err
}
defer file.Close()
// create packed world data
var tmp World
tmp.p = soa.DefaultManager.Pack(w.p).([]int32)
tmp.v = soa.DefaultManager.Pack(w.v).([]int32)
// encode data to JSON
if err := json.NewEncoder(file).Encode(&tmp); err != nil {
return err
}
return nil
}
Unpack
Next time we load the world from the file and unpack the data:
func loadWorld(filename string) (w *World, err error) {
// open a new file
file, err := os.Open(filename)
if err != nil {
return nil, err
}
defer file.Close()
// decode data from JSON
var tmp World
if err := json.NewDecoder(file).Decode(&tmp); err != nil {
return nil, err
}
tmp.p = soa.DefaultManager.Unpack(tmp.p).([]int32)
tmp.v = soa.DefaultManager.Unpack(tmp.v).([]int32)
return &tmp, nil
}
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
var DefaultManager = NewManager()
DefaultManager creates a single instance of Manager at startup.
Functions ¶
This section is empty.
Types ¶
type Manager ¶
type Manager struct {
// contains filtered or unexported fields
}
Manager encapsulates the state and logic.
func NewManager ¶
func NewManager() *Manager
NewManager creates a new Manager and returns its pointer.
func (*Manager) Allocate ¶
func (m *Manager) Allocate(s interface{}) (t interface{})
Allocate creates a new slice s by using a total size of the page size. The length and capacity is set to "page size / size of type". All values are initialized with zero (0).
func (*Manager) Grow ¶
func (m *Manager) Grow(s interface{}) (t interface{})
Grow appends a new page of values to a given slice s and save it as a new slice t.
Source Files