1// Copyright (c) 2020-{{.ToYear}} Uber Technologies, Inc.
2//
3// Permission is hereby granted, free of charge, to any person obtaining a copy
4// of this software and associated documentation files (the "Software"), to deal
5// in the Software without restriction, including without limitation the rights
6// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
7// copies of the Software, and to permit persons to whom the Software is
8// furnished to do so, subject to the following conditions:
9//
10// The above copyright notice and this permission notice shall be included in
11// all copies or substantial portions of the Software.
12//
13// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
18// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
19// THE SOFTWARE.
20
21package atomic
22
23{{ with .Imports }}
24import (
25 {{ range . -}}
26 {{ printf "%q" . }}
27 {{ end }}
28)
29{{ end }}
30
31// {{ .Name }} is an atomic type-safe wrapper for {{ .Type }} values.
32type {{ .Name }} struct{
33 _ nocmp // disallow non-atomic comparison
34
35 v {{ .Wrapped }}
36}
37
38var _zero{{ .Name }} {{ .Type }}
39
40
41// New{{ .Name }} creates a new {{ .Name }}.
42func New{{ .Name }}(val {{ .Type }}) *{{ .Name }} {
43 x := &{{ .Name }}{}
44 if val != _zero{{ .Name }} {
45 x.Store(val)
46 }
47 return x
48}
49
50// Load atomically loads the wrapped {{ .Type }}.
51func (x *{{ .Name }}) Load() {{ .Type }} {
52 {{ if .Unpack -}}
53 return {{ .Unpack }}(x.v.Load())
54 {{- else -}}
55 if v := x.v.Load(); v != nil {
56 return v.({{ .Type }})
57 }
58 return _zero{{ .Name }}
59 {{- end }}
60}
61
62// Store atomically stores the passed {{ .Type }}.
63func (x *{{ .Name }}) Store(val {{ .Type }}) {
64 x.v.Store({{ .Pack }}(val))
65}
66
67{{ if .CAS -}}
68 // CAS is an atomic compare-and-swap for {{ .Type }} values.
69 //
70 // Deprecated: Use CompareAndSwap.
71 func (x *{{ .Name }}) CAS(old, new {{ .Type }}) (swapped bool) {
72 return x.CompareAndSwap(old, new)
73 }
74{{- end }}
75
76{{ if .CompareAndSwap -}}
77 // CompareAndSwap is an atomic compare-and-swap for {{ .Type }} values.
78 func (x *{{ .Name }}) CompareAndSwap(old, new {{ .Type }}) (swapped bool) {
79 {{ if eq .Wrapped "Value" -}}
80 if x.v.CompareAndSwap({{ .Pack }}(old), {{ .Pack }}(new)) {
81 return true
82 }
83
84 if old == _zero{{ .Name }} {
85 // If the old value is the empty value, then it's possible the
86 // underlying Value hasn't been set and is nil, so retry with nil.
87 return x.v.CompareAndSwap(nil, {{ .Pack }}(new))
88 }
89
90 return false
91 {{- else -}}
92 return x.v.CompareAndSwap({{ .Pack }}(old), {{ .Pack }}(new))
93 {{- end }}
94 }
95{{- end }}
96
97{{ if .Swap -}}
98 // Swap atomically stores the given {{ .Type }} and returns the old
99 // value.
100 func (x *{{ .Name }}) Swap(val {{ .Type }}) (old {{ .Type }}) {
101 return {{ .Unpack }}(x.v.Swap({{ .Pack }}(val)))
102 }
103{{- end }}
104
105{{ if .JSON -}}
106 // MarshalJSON encodes the wrapped {{ .Type }} into JSON.
107 func (x *{{ .Name }}) MarshalJSON() ([]byte, error) {
108 return json.Marshal(x.Load())
109 }
110
111 // UnmarshalJSON decodes a {{ .Type }} from JSON.
112 func (x *{{ .Name }}) UnmarshalJSON(b []byte) error {
113 var v {{ .Type }}
114 if err := json.Unmarshal(b, &v); err != nil {
115 return err
116 }
117 x.Store(v)
118 return nil
119 }
120{{- end }}
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