summaryrefslogtreecommitdiff
path: root/libgo/go/sync/map_reference_test.go
blob: 9f27b07c3292ba3dfa22e7039dc9882a1b80706c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sync_test

import (
	"sync"
	"sync/atomic"
)

// This file contains reference map implementations for unit-tests.

// mapInterface is the interface Map implements.
type mapInterface interface {
	Load(interface{}) (interface{}, bool)
	Store(key, value interface{})
	LoadOrStore(key, value interface{}) (actual interface{}, loaded bool)
	Delete(interface{})
	Range(func(key, value interface{}) (shouldContinue bool))
}

// RWMutexMap is an implementation of mapInterface using a sync.RWMutex.
type RWMutexMap struct {
	mu    sync.RWMutex
	dirty map[interface{}]interface{}
}

func (m *RWMutexMap) Load(key interface{}) (value interface{}, ok bool) {
	m.mu.RLock()
	value, ok = m.dirty[key]
	m.mu.RUnlock()
	return
}

func (m *RWMutexMap) Store(key, value interface{}) {
	m.mu.Lock()
	if m.dirty == nil {
		m.dirty = make(map[interface{}]interface{})
	}
	m.dirty[key] = value
	m.mu.Unlock()
}

func (m *RWMutexMap) LoadOrStore(key, value interface{}) (actual interface{}, loaded bool) {
	m.mu.Lock()
	actual, loaded = m.dirty[key]
	if !loaded {
		actual = value
		if m.dirty == nil {
			m.dirty = make(map[interface{}]interface{})
		}
		m.dirty[key] = value
	}
	m.mu.Unlock()
	return actual, loaded
}

func (m *RWMutexMap) Delete(key interface{}) {
	m.mu.Lock()
	delete(m.dirty, key)
	m.mu.Unlock()
}

func (m *RWMutexMap) Range(f func(key, value interface{}) (shouldContinue bool)) {
	m.mu.RLock()
	keys := make([]interface{}, 0, len(m.dirty))
	for k := range m.dirty {
		keys = append(keys, k)
	}
	m.mu.RUnlock()

	for _, k := range keys {
		v, ok := m.Load(k)
		if !ok {
			continue
		}
		if !f(k, v) {
			break
		}
	}
}

// DeepCopyMap is an implementation of mapInterface using a Mutex and
// atomic.Value.  It makes deep copies of the map on every write to avoid
// acquiring the Mutex in Load.
type DeepCopyMap struct {
	mu    sync.Mutex
	clean atomic.Value
}

func (m *DeepCopyMap) Load(key interface{}) (value interface{}, ok bool) {
	clean, _ := m.clean.Load().(map[interface{}]interface{})
	value, ok = clean[key]
	return value, ok
}

func (m *DeepCopyMap) Store(key, value interface{}) {
	m.mu.Lock()
	dirty := m.dirty()
	dirty[key] = value
	m.clean.Store(dirty)
	m.mu.Unlock()
}

func (m *DeepCopyMap) LoadOrStore(key, value interface{}) (actual interface{}, loaded bool) {
	clean, _ := m.clean.Load().(map[interface{}]interface{})
	actual, loaded = clean[key]
	if loaded {
		return actual, loaded
	}

	m.mu.Lock()
	// Reload clean in case it changed while we were waiting on m.mu.
	clean, _ = m.clean.Load().(map[interface{}]interface{})
	actual, loaded = clean[key]
	if !loaded {
		dirty := m.dirty()
		dirty[key] = value
		actual = value
		m.clean.Store(dirty)
	}
	m.mu.Unlock()
	return actual, loaded
}

func (m *DeepCopyMap) Delete(key interface{}) {
	m.mu.Lock()
	dirty := m.dirty()
	delete(dirty, key)
	m.clean.Store(dirty)
	m.mu.Unlock()
}

func (m *DeepCopyMap) Range(f func(key, value interface{}) (shouldContinue bool)) {
	clean, _ := m.clean.Load().(map[interface{}]interface{})
	for k, v := range clean {
		if !f(k, v) {
			break
		}
	}
}

func (m *DeepCopyMap) dirty() map[interface{}]interface{} {
	clean, _ := m.clean.Load().(map[interface{}]interface{})
	dirty := make(map[interface{}]interface{}, len(clean)+1)
	for k, v := range clean {
		dirty[k] = v
	}
	return dirty
}