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// 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
}
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