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// Copyright 2019 The gVisor Authors.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package seqatomic doesn't exist. This file must be instantiated using the
// go_template_instance rule in tools/go_generics/defs.bzl.
package seqatomic
import (
"sync/atomic"
"unsafe"
)
// Value is a required type parameter.
type Value struct{}
// An AtomicPtr is a pointer to a value of type Value that can be atomically
// loaded and stored. The zero value of an AtomicPtr represents nil.
//
// Note that copying AtomicPtr by value performs a non-atomic read of the
// stored pointer, which is unsafe if Store() can be called concurrently; in
// this case, do `dst.Store(src.Load())` instead.
//
// +stateify savable
type AtomicPtr struct {
ptr unsafe.Pointer `state:".(*Value)"`
}
func (p *AtomicPtr) savePtr() *Value {
return p.Load()
}
func (p *AtomicPtr) loadPtr(v *Value) {
p.Store(v)
}
// Load returns the value set by the most recent Store. It returns nil if there
// has been no previous call to Store.
//
//go:nosplit
func (p *AtomicPtr) Load() *Value {
return (*Value)(atomic.LoadPointer(&p.ptr))
}
// Store sets the value returned by Load to x.
func (p *AtomicPtr) Store(x *Value) {
atomic.StorePointer(&p.ptr, (unsafe.Pointer)(x))
}
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