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