47 lines
1.5 KiB
Go
47 lines
1.5 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package template doesn't exist. This file must be instantiated using the
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// go_template_instance rule in tools/go_generics/defs.bzl.
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package template
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import (
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"sync/atomic"
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"unsafe"
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)
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// Value is a required type parameter.
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type Value struct{}
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// An AtomicPtr is a pointer to a value of type Value that can be atomically
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// loaded and stored. The zero value of an AtomicPtr represents nil.
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//
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// Note that copying AtomicPtr by value performs a non-atomic read of the
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// stored pointer, which is unsafe if Store() can be called concurrently; in
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// this case, do `dst.Store(src.Load())` instead.
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type AtomicPtr struct {
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ptr unsafe.Pointer
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}
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// Load returns the value set by the most recent Store. It returns nil if there
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// has been no previous call to Store.
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func (p *AtomicPtr) Load() *Value {
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return (*Value)(atomic.LoadPointer(&p.ptr))
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}
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// Store sets the value returned by Load to x.
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func (p *AtomicPtr) Store(x *Value) {
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atomic.StorePointer(&p.ptr, (unsafe.Pointer)(x))
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}
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