1 files changed, 271 insertions, 0 deletions
diff --git a/src/sync/map_reference_test.go b/src/sync/map_reference_test.go
new file mode 100644
index 0000000..aa5ebf3
--- /dev/null
+++ b/src/sync/map_reference_test.go
@@ -0,0 +1,271 @@
+// 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(any) (any, bool)
+	Store(key, value any)
+	LoadOrStore(key, value any) (actual any, loaded bool)
+	LoadAndDelete(key any) (value any, loaded bool)
+	Delete(any)
+	Swap(key, value any) (previous any, loaded bool)
+	CompareAndSwap(key, old, new any) (swapped bool)
+	CompareAndDelete(key, old any) (deleted bool)
+	Range(func(key, value any) (shouldContinue bool))
+}
+
+var (
+	_ mapInterface = &RWMutexMap{}
+	_ mapInterface = &DeepCopyMap{}
+)
+
+// RWMutexMap is an implementation of mapInterface using a sync.RWMutex.
+type RWMutexMap struct {
+	mu    sync.RWMutex
+	dirty map[any]any
+}
+
+func (m *RWMutexMap) Load(key any) (value any, ok bool) {
+	m.mu.RLock()
+	value, ok = m.dirty[key]
+	m.mu.RUnlock()
+	return
+}
+
+func (m *RWMutexMap) Store(key, value any) {
+	m.mu.Lock()
+	if m.dirty == nil {
+		m.dirty = make(map[any]any)
+	}
+	m.dirty[key] = value
+	m.mu.Unlock()
+}
+
+func (m *RWMutexMap) LoadOrStore(key, value any) (actual any, loaded bool) {
+	m.mu.Lock()
+	actual, loaded = m.dirty[key]
+	if !loaded {
+		actual = value
+		if m.dirty == nil {
+			m.dirty = make(map[any]any)
+		}
+		m.dirty[key] = value
+	}
+	m.mu.Unlock()
+	return actual, loaded
+}
+
+func (m *RWMutexMap) Swap(key, value any) (previous any, loaded bool) {
+	m.mu.Lock()
+	if m.dirty == nil {
+		m.dirty = make(map[any]any)
+	}
+
+	previous, loaded = m.dirty[key]
+	m.dirty[key] = value
+	m.mu.Unlock()
+	return
+}
+
+func (m *RWMutexMap) LoadAndDelete(key any) (value any, loaded bool) {
+	m.mu.Lock()
+	value, loaded = m.dirty[key]
+	if !loaded {
+		m.mu.Unlock()
+		return nil, false
+	}
+	delete(m.dirty, key)
+	m.mu.Unlock()
+	return value, loaded
+}
+
+func (m *RWMutexMap) Delete(key any) {
+	m.mu.Lock()
+	delete(m.dirty, key)
+	m.mu.Unlock()
+}
+
+func (m *RWMutexMap) CompareAndSwap(key, old, new any) (swapped bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.dirty == nil {
+		return false
+	}
+
+	value, loaded := m.dirty[key]
+	if loaded && value == old {
+		m.dirty[key] = new
+		return true
+	}
+	return false
+}
+
+func (m *RWMutexMap) CompareAndDelete(key, old any) (deleted bool) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if m.dirty == nil {
+		return false
+	}
+
+	value, loaded := m.dirty[key]
+	if loaded && value == old {
+		delete(m.dirty, key)
+		return true
+	}
+	return false
+}
+
+func (m *RWMutexMap) Range(f func(key, value any) (shouldContinue bool)) {
+	m.mu.RLock()
+	keys := make([]any, 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 any) (value any, ok bool) {
+	clean, _ := m.clean.Load().(map[any]any)
+	value, ok = clean[key]
+	return value, ok
+}
+
+func (m *DeepCopyMap) Store(key, value any) {
+	m.mu.Lock()
+	dirty := m.dirty()
+	dirty[key] = value
+	m.clean.Store(dirty)
+	m.mu.Unlock()
+}
+
+func (m *DeepCopyMap) LoadOrStore(key, value any) (actual any, loaded bool) {
+	clean, _ := m.clean.Load().(map[any]any)
+	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[any]any)
+	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) Swap(key, value any) (previous any, loaded bool) {
+	m.mu.Lock()
+	dirty := m.dirty()
+	previous, loaded = dirty[key]
+	dirty[key] = value
+	m.clean.Store(dirty)
+	m.mu.Unlock()
+	return
+}
+
+func (m *DeepCopyMap) LoadAndDelete(key any) (value any, loaded bool) {
+	m.mu.Lock()
+	dirty := m.dirty()
+	value, loaded = dirty[key]
+	delete(dirty, key)
+	m.clean.Store(dirty)
+	m.mu.Unlock()
+	return
+}
+
+func (m *DeepCopyMap) Delete(key any) {
+	m.mu.Lock()
+	dirty := m.dirty()
+	delete(dirty, key)
+	m.clean.Store(dirty)
+	m.mu.Unlock()
+}
+
+func (m *DeepCopyMap) CompareAndSwap(key, old, new any) (swapped bool) {
+	clean, _ := m.clean.Load().(map[any]any)
+	if previous, ok := clean[key]; !ok || previous != old {
+		return false
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	dirty := m.dirty()
+	value, loaded := dirty[key]
+	if loaded && value == old {
+		dirty[key] = new
+		m.clean.Store(dirty)
+		return true
+	}
+	return false
+}
+
+func (m *DeepCopyMap) CompareAndDelete(key, old any) (deleted bool) {
+	clean, _ := m.clean.Load().(map[any]any)
+	if previous, ok := clean[key]; !ok || previous != old {
+		return false
+	}
+
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	dirty := m.dirty()
+	value, loaded := dirty[key]
+	if loaded && value == old {
+		delete(dirty, key)
+		m.clean.Store(dirty)
+		return true
+	}
+	return false
+}
+
+func (m *DeepCopyMap) Range(f func(key, value any) (shouldContinue bool)) {
+	clean, _ := m.clean.Load().(map[any]any)
+	for k, v := range clean {
+		if !f(k, v) {
+			break
+		}
+	}
+}
+
+func (m *DeepCopyMap) dirty() map[any]any {
+	clean, _ := m.clean.Load().(map[any]any)
+	dirty := make(map[any]any, len(clean)+1)
+	for k, v := range clean {
+		dirty[k] = v
+	}
+	return dirty
+}