121 lines
3.4 KiB
Cheetah
121 lines
3.4 KiB
Cheetah
// Copyright (c) 2020-{{.ToYear}} Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package atomic
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{{ with .Imports }}
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import (
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{{ range . -}}
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{{ printf "%q" . }}
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{{ end }}
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)
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{{ end }}
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// {{ .Name }} is an atomic type-safe wrapper for {{ .Type }} values.
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type {{ .Name }} struct{
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_ nocmp // disallow non-atomic comparison
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v {{ .Wrapped }}
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}
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var _zero{{ .Name }} {{ .Type }}
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// New{{ .Name }} creates a new {{ .Name }}.
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func New{{ .Name }}(val {{ .Type }}) *{{ .Name }} {
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x := &{{ .Name }}{}
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if val != _zero{{ .Name }} {
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x.Store(val)
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}
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return x
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}
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// Load atomically loads the wrapped {{ .Type }}.
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func (x *{{ .Name }}) Load() {{ .Type }} {
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{{ if .Unpack -}}
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return {{ .Unpack }}(x.v.Load())
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{{- else -}}
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if v := x.v.Load(); v != nil {
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return v.({{ .Type }})
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}
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return _zero{{ .Name }}
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{{- end }}
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}
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// Store atomically stores the passed {{ .Type }}.
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func (x *{{ .Name }}) Store(val {{ .Type }}) {
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x.v.Store({{ .Pack }}(val))
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}
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{{ if .CAS -}}
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// CAS is an atomic compare-and-swap for {{ .Type }} values.
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//
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// Deprecated: Use CompareAndSwap.
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func (x *{{ .Name }}) CAS(old, new {{ .Type }}) (swapped bool) {
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return x.CompareAndSwap(old, new)
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}
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{{- end }}
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{{ if .CompareAndSwap -}}
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// CompareAndSwap is an atomic compare-and-swap for {{ .Type }} values.
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func (x *{{ .Name }}) CompareAndSwap(old, new {{ .Type }}) (swapped bool) {
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{{ if eq .Wrapped "Value" -}}
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if x.v.CompareAndSwap({{ .Pack }}(old), {{ .Pack }}(new)) {
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return true
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}
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if old == _zero{{ .Name }} {
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// If the old value is the empty value, then it's possible the
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// underlying Value hasn't been set and is nil, so retry with nil.
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return x.v.CompareAndSwap(nil, {{ .Pack }}(new))
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}
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return false
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{{- else -}}
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return x.v.CompareAndSwap({{ .Pack }}(old), {{ .Pack }}(new))
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{{- end }}
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}
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{{- end }}
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{{ if .Swap -}}
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// Swap atomically stores the given {{ .Type }} and returns the old
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// value.
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func (x *{{ .Name }}) Swap(val {{ .Type }}) (old {{ .Type }}) {
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return {{ .Unpack }}(x.v.Swap({{ .Pack }}(val)))
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}
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{{- end }}
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{{ if .JSON -}}
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// MarshalJSON encodes the wrapped {{ .Type }} into JSON.
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func (x *{{ .Name }}) MarshalJSON() (by, er) {
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return json.Marshal(x.Load())
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}
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// UnmarshalJSON decodes a {{ .Type }} from JSON.
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func (x *{{ .Name }}) UnmarshalJSON(b by) er {
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var v {{ .Type }}
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if err := json.Unmarshal(b, &v); err != nil {
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return err
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}
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x.Store(v)
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return nil
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}
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{{- end }}
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