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package atomics
import (
"sync/atomic"
"unsafe"
)
// Bytes provides user-friendly means of performing atomic operations on []byte types.
type Bytes struct{ ptr unsafe.Pointer }
// NewBytes will return a new Bytes instance initialized with zero value.
func NewBytes() *Bytes {
var v []byte
return &Bytes{
ptr: unsafe.Pointer(&v),
}
}
// Store will atomically store []byte value in address contained within v.
func (v *Bytes) Store(val []byte) {
atomic.StorePointer(&v.ptr, unsafe.Pointer(&val))
}
// Load will atomically load []byte value at address contained within v.
func (v *Bytes) Load() []byte {
return *(*[]byte)(atomic.LoadPointer(&v.ptr))
}
// CAS performs a compare-and-swap for a(n) []byte value at address contained within v.
func (v *Bytes) CAS(cmp, swp []byte) bool {
for {
// Load current value at address
ptr := atomic.LoadPointer(&v.ptr)
cur := *(*[]byte)(ptr)
// Perform comparison against current
if !(string(cur) == string(cmp)) {
return false
}
// Attempt to replace pointer
if atomic.CompareAndSwapPointer(
&v.ptr,
ptr,
unsafe.Pointer(&swp),
) {
return true
}
}
}
// Swap atomically stores new []byte value into address contained within v, and returns previous value.
func (v *Bytes) Swap(swp []byte) []byte {
ptr := unsafe.Pointer(&swp)
ptr = atomic.SwapPointer(&v.ptr, ptr)
return *(*[]byte)(ptr)
}
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