yggdrasil-go/src/util/util.go

package util

// These are misc. utility functions that didn't really fit anywhere else

import "runtime"
import "time"

// A wrapper around runtime.Gosched() so it doesn't need to be imported elsewhere.
func Yield() {
	runtime.Gosched()
}

// A wrapper around runtime.LockOSThread() so it doesn't need to be imported elsewhere.
func LockThread() {
	runtime.LockOSThread()
}

// A wrapper around runtime.UnlockOSThread() so it doesn't need to be imported elsewhere.
func UnlockThread() {
	runtime.UnlockOSThread()
}

// This is used to buffer recently used slices of bytes, to prevent allocations in the hot loops.
// It's used like a sync.Pool, but with a fixed size and typechecked without type casts to/from interface{} (which were making the profiles look ugly).
var byteStore chan []byte

func init() {
	byteStore = make(chan []byte, 32)
}

// Gets an empty slice from the byte store, if one is available, or else returns a new nil slice.
func GetBytes() []byte {
	select {
	case bs := <-byteStore:
		return bs[:0]
	default:
		return nil
	}
}

// Puts a slice in the store, if there's room, or else returns and lets the slice get collected.
func PutBytes(bs []byte) {
	select {
	case byteStore <- bs:
	default:
	}
}

// This is a workaround to go's broken timer implementation
func TimerStop(t *time.Timer) bool {
	if !t.Stop() {
		select {
		case <-t.C:
		default:
		}
	}
	return true
}