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author | kevin.xu <cming.xu@gmail.com> | 2020-04-27 21:51:31 +0800 |
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committer | GitHub <noreply@github.com> | 2020-04-27 21:51:31 +0800 |
commit | e896ca54db67524afc20b644d43c72185e72dc0e (patch) | |
tree | 2a16f3a62a5cafd098f1f028c621f1b655589d69 /pkg/sync/atomicptr_unsafe.go | |
parent | 1f19624fa127d7d59cabe29593cc80b7fe6c81f8 (diff) | |
parent | 3c67754663f424f2ebbc0ff2a4c80e30618d5355 (diff) |
Merge pull request #1 from google/master
catch up
Diffstat (limited to 'pkg/sync/atomicptr_unsafe.go')
-rw-r--r-- | pkg/sync/atomicptr_unsafe.go | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/pkg/sync/atomicptr_unsafe.go b/pkg/sync/atomicptr_unsafe.go new file mode 100644 index 000000000..525c4beed --- /dev/null +++ b/pkg/sync/atomicptr_unsafe.go @@ -0,0 +1,47 @@ +// 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 template doesn't exist. This file must be instantiated using the +// go_template_instance rule in tools/go_generics/defs.bzl. +package template + +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. +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)) +} |