--- /dev/null
+// 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
+
+import (
+ "sync/atomic"
+ "unsafe"
+)
+
+// Map is a concurrent map with amortized-constant-time loads, stores, and deletes.
+// It is safe for multiple goroutines to call a Map's methods concurrently.
+//
+// The zero Map is valid and empty.
+//
+// A Map must not be copied after first use.
+type Map struct {
+ mu Mutex
+
+ // read contains the portion of the map's contents that are safe for
+ // concurrent access (with or without mu held).
+ //
+ // The read field itself is always safe to load, but must only be stored with
+ // mu held.
+ //
+ // Entries stored in read may be updated concurrently without mu, but updating
+ // a previously-expunged entry requires that the entry be copied to the dirty
+ // map and unexpunged with mu held.
+ read atomic.Value // readOnly
+
+ // dirty contains the portion of the map's contents that require mu to be
+ // held. To ensure that the dirty map can be promoted to the read map quickly,
+ // it also includes all of the non-expunged entries in the read map.
+ //
+ // Expunged entries are not stored in the dirty map. An expunged entry in the
+ // clean map must be unexpunged and added to the dirty map before a new value
+ // can be stored to it.
+ //
+ // If the dirty map is nil, the next write to the map will initialize it by
+ // making a shallow copy of the clean map, omitting stale entries.
+ dirty map[interface{}]*entry
+
+ // misses counts the number of loads since the read map was last updated that
+ // needed to lock mu to determine whether the key was present.
+ //
+ // Once enough misses have occurred to cover the cost of copying the dirty
+ // map, the dirty map will be promoted to the read map (in the unamended
+ // state) and the next store to the map will make a new dirty copy.
+ misses int
+}
+
+// readOnly is an immutable struct stored atomically in the Map.read field.
+type readOnly struct {
+ m map[interface{}]*entry
+ amended bool // true if the dirty map contains some key not in m.
+}
+
+// expunged is an arbitrary pointer that marks entries which have been deleted
+// from the dirty map.
+var expunged = unsafe.Pointer(new(interface{}))
+
+// An entry is a slot in the map corresponding to a particular key.
+type entry struct {
+ // p points to the interface{} value stored for the entry.
+ //
+ // If p == nil, the entry has been deleted and m.dirty == nil.
+ //
+ // If p == expunged, the entry has been deleted, m.dirty != nil, and the entry
+ // is missing from m.dirty.
+ //
+ // Otherwise, the entry is valid and recorded in m.read.m[key] and, if m.dirty
+ // != nil, in m.dirty[key].
+ //
+ // An entry can be deleted by atomic replacement with nil: when m.dirty is
+ // next created, it will atomically replace nil with expunged and leave
+ // m.dirty[key] unset.
+ //
+ // An entry's associated value can be updated by atomic replacement, provided
+ // p != expunged. If p == expunged, an entry's associated value can be updated
+ // only after first setting m.dirty[key] = e so that lookups using the dirty
+ // map find the entry.
+ p unsafe.Pointer // *interface{}
+}
+
+func newEntry(i interface{}) *entry {
+ return &entry{p: unsafe.Pointer(&i)}
+}
+
+// Load returns the value stored in the map for a key, or nil if no
+// value is present.
+// The ok result indicates whether value was found in the map.
+func (m *Map) Load(key interface{}) (value interface{}, ok bool) {
+ read, _ := m.read.Load().(readOnly)
+ e, ok := read.m[key]
+ if !ok && read.amended {
+ m.mu.Lock()
+ // Avoid reporting a spurious miss if m.dirty got promoted while we were
+ // blocked on m.mu. (If further loads of the same key will not miss, it's
+ // not worth copying the dirty map for this key.)
+ read, _ = m.read.Load().(readOnly)
+ e, ok = read.m[key]
+ if !ok && read.amended {
+ e, ok = m.dirty[key]
+ // Regardless of whether the entry was present, record a miss: this key
+ // will take the slow path until the dirty map is promoted to the read
+ // map.
+ m.missLocked()
+ }
+ m.mu.Unlock()
+ }
+ if !ok {
+ return nil, false
+ }
+ return e.load()
+}
+
+func (e *entry) load() (value interface{}, ok bool) {
+ p := atomic.LoadPointer(&e.p)
+ if p == nil || p == expunged {
+ return nil, false
+ }
+ return *(*interface{})(p), true
+}
+
+// Store sets the value for a key.
+func (m *Map) Store(key, value interface{}) {
+ read, _ := m.read.Load().(readOnly)
+ if e, ok := read.m[key]; ok && e.tryStore(&value) {
+ return
+ }
+
+ m.mu.Lock()
+ read, _ = m.read.Load().(readOnly)
+ if e, ok := read.m[key]; ok {
+ if e.unexpungeLocked() {
+ // The entry was previously expunged, which implies that there is a
+ // non-nil dirty map and this entry is not in it.
+ m.dirty[key] = e
+ }
+ e.storeLocked(&value)
+ } else if e, ok := m.dirty[key]; ok {
+ e.storeLocked(&value)
+ } else {
+ if !read.amended {
+ // We're adding the first new key to the dirty map.
+ // Make sure it is allocated and mark the read-only map as incomplete.
+ m.dirtyLocked()
+ m.read.Store(readOnly{m: read.m, amended: true})
+ }
+ m.dirty[key] = newEntry(value)
+ }
+ m.mu.Unlock()
+}
+
+// tryStore stores a value if the entry has not been expunged.
+//
+// If the entry is expunged, tryStore returns false and leaves the entry
+// unchanged.
+func (e *entry) tryStore(i *interface{}) bool {
+ p := atomic.LoadPointer(&e.p)
+ if p == expunged {
+ return false
+ }
+ for {
+ if atomic.CompareAndSwapPointer(&e.p, p, unsafe.Pointer(i)) {
+ return true
+ }
+ p = atomic.LoadPointer(&e.p)
+ if p == expunged {
+ return false
+ }
+ }
+}
+
+// unexpungeLocked ensures that the entry is not marked as expunged.
+//
+// If the entry was previously expunged, it must be added to the dirty map
+// before m.mu is unlocked.
+func (e *entry) unexpungeLocked() (wasExpunged bool) {
+ return atomic.CompareAndSwapPointer(&e.p, expunged, nil)
+}
+
+// storeLocked unconditionally stores a value to the entry.
+//
+// The entry must be known not to be expunged.
+func (e *entry) storeLocked(i *interface{}) {
+ atomic.StorePointer(&e.p, unsafe.Pointer(i))
+}
+
+// LoadOrStore returns the existing value for the key if present.
+// Otherwise, it stores and returns the given value.
+// The loaded result is true if the value was loaded, false if stored.
+func (m *Map) LoadOrStore(key, value interface{}) (actual interface{}, loaded bool) {
+ // Avoid locking if it's a clean hit.
+ read, _ := m.read.Load().(readOnly)
+ if e, ok := read.m[key]; ok {
+ actual, loaded, ok := e.tryLoadOrStore(value)
+ if ok {
+ return actual, loaded
+ }
+ }
+
+ m.mu.Lock()
+ read, _ = m.read.Load().(readOnly)
+ if e, ok := read.m[key]; ok {
+ if e.unexpungeLocked() {
+ m.dirty[key] = e
+ }
+ actual, loaded, _ = e.tryLoadOrStore(value)
+ } else if e, ok := m.dirty[key]; ok {
+ actual, loaded, _ = e.tryLoadOrStore(value)
+ m.missLocked()
+ } else {
+ if !read.amended {
+ // We're adding the first new key to the dirty map.
+ // Make sure it is allocated and mark the read-only map as incomplete.
+ m.dirtyLocked()
+ m.read.Store(readOnly{m: read.m, amended: true})
+ }
+ m.dirty[key] = newEntry(value)
+ actual, loaded = value, false
+ }
+ m.mu.Unlock()
+
+ return actual, loaded
+}
+
+// tryLoadOrStore atomically loads or stores a value if the entry is not
+// expunged.
+//
+// If the entry is expunged, tryLoadOrStore leaves the entry unchanged and
+// returns with ok==false.
+func (e *entry) tryLoadOrStore(i interface{}) (actual interface{}, loaded, ok bool) {
+ p := atomic.LoadPointer(&e.p)
+ if p == expunged {
+ return nil, false, false
+ }
+ if p != nil {
+ return *(*interface{})(p), true, true
+ }
+
+ // Copy the interface after the first load to make this method more amenable
+ // to escape analysis: if we hit the "load" path or the entry is expunged, we
+ // shouldn't bother heap-allocating.
+ ic := i
+ for {
+ if atomic.CompareAndSwapPointer(&e.p, nil, unsafe.Pointer(&ic)) {
+ return i, false, true
+ }
+ p = atomic.LoadPointer(&e.p)
+ if p == expunged {
+ return nil, false, false
+ }
+ if p != nil {
+ return *(*interface{})(p), true, true
+ }
+ }
+}
+
+// Delete deletes the value for a key.
+func (m *Map) Delete(key interface{}) {
+ read, _ := m.read.Load().(readOnly)
+ e, ok := read.m[key]
+ if !ok && read.amended {
+ m.mu.Lock()
+ read, _ = m.read.Load().(readOnly)
+ e, ok = read.m[key]
+ if !ok && read.amended {
+ delete(m.dirty, key)
+ }
+ m.mu.Unlock()
+ }
+ if ok {
+ e.delete()
+ }
+}
+
+func (e *entry) delete() (hadValue bool) {
+ for {
+ p := atomic.LoadPointer(&e.p)
+ if p == nil || p == expunged {
+ return false
+ }
+ if atomic.CompareAndSwapPointer(&e.p, p, nil) {
+ return true
+ }
+ }
+}
+
+// Range calls f sequentially for each key and value present in the map.
+// If f returns false, range stops the iteration.
+//
+// Range does not necessarily correspond to any consistent snapshot of the Map's
+// contents: no key will be visited more than once, but if the value for any key
+// is stored or deleted concurrently, Range may reflect any mapping for that key
+// from any point during the Range call.
+//
+// Range may be O(N) with the number of elements in the map even if f returns
+// false after a constant number of calls.
+func (m *Map) Range(f func(key, value interface{}) bool) {
+ // We need to be able to iterate over all of the keys that were already
+ // present at the start of the call to Range.
+ // If read.amended is false, then read.m satisfies that property without
+ // requiring us to hold m.mu for a long time.
+ read, _ := m.read.Load().(readOnly)
+ if read.amended {
+ // m.dirty contains keys not in read.m. Fortunately, Range is already O(N)
+ // (assuming the caller does not break out early), so a call to Range
+ // amortizes an entire copy of the map: we can promote the dirty copy
+ // immediately!
+ m.mu.Lock()
+ read, _ = m.read.Load().(readOnly)
+ if read.amended {
+ read = readOnly{m: m.dirty}
+ m.read.Store(read)
+ m.dirty = nil
+ m.misses = 0
+ }
+ m.mu.Unlock()
+ }
+
+ for k, e := range read.m {
+ v, ok := e.load()
+ if !ok {
+ continue
+ }
+ if !f(k, v) {
+ break
+ }
+ }
+}
+
+func (m *Map) missLocked() {
+ m.misses++
+ if m.misses < len(m.dirty) {
+ return
+ }
+ m.read.Store(readOnly{m: m.dirty})
+ m.dirty = nil
+ m.misses = 0
+}
+
+func (m *Map) dirtyLocked() {
+ if m.dirty != nil {
+ return
+ }
+
+ read, _ := m.read.Load().(readOnly)
+ m.dirty = make(map[interface{}]*entry, len(read.m))
+ for k, e := range read.m {
+ if !e.tryExpungeLocked() {
+ m.dirty[k] = e
+ }
+ }
+}
+
+func (e *entry) tryExpungeLocked() (isExpunged bool) {
+ p := atomic.LoadPointer(&e.p)
+ for p == nil {
+ if atomic.CompareAndSwapPointer(&e.p, nil, expunged) {
+ return true
+ }
+ p = atomic.LoadPointer(&e.p)
+ }
+ return p == expunged
+}
--- /dev/null
+// 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 (
+ "fmt"
+ "reflect"
+ "sync"
+ "sync/atomic"
+ "testing"
+)
+
+type bench struct {
+ setup func(*testing.B, mapInterface)
+ perG func(b *testing.B, pb *testing.PB, i int, m mapInterface)
+}
+
+func benchMap(b *testing.B, bench bench) {
+ for _, m := range [...]mapInterface{&DeepCopyMap{}, &RWMutexMap{}, &sync.Map{}} {
+ b.Run(fmt.Sprintf("%T", m), func(b *testing.B) {
+ m = reflect.New(reflect.TypeOf(m).Elem()).Interface().(mapInterface)
+ if bench.setup != nil {
+ bench.setup(b, m)
+ }
+
+ b.ResetTimer()
+
+ var i int64
+ b.RunParallel(func(pb *testing.PB) {
+ id := int(atomic.AddInt64(&i, 1) - 1)
+ bench.perG(b, pb, id*b.N, m)
+ })
+ })
+ }
+}
+
+func BenchmarkLoadMostlyHits(b *testing.B) {
+ const hits, misses = 1023, 1
+
+ benchMap(b, bench{
+ setup: func(_ *testing.B, m mapInterface) {
+ for i := 0; i < hits; i++ {
+ m.LoadOrStore(i, i)
+ }
+ // Prime the map to get it into a steady state.
+ for i := 0; i < hits*2; i++ {
+ m.Load(i % hits)
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.Load(i % (hits + misses))
+ }
+ },
+ })
+}
+
+func BenchmarkLoadMostlyMisses(b *testing.B) {
+ const hits, misses = 1, 1023
+
+ benchMap(b, bench{
+ setup: func(_ *testing.B, m mapInterface) {
+ for i := 0; i < hits; i++ {
+ m.LoadOrStore(i, i)
+ }
+ // Prime the map to get it into a steady state.
+ for i := 0; i < hits*2; i++ {
+ m.Load(i % hits)
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.Load(i % (hits + misses))
+ }
+ },
+ })
+}
+
+func BenchmarkLoadOrStoreBalanced(b *testing.B) {
+ const hits, misses = 128, 128
+
+ benchMap(b, bench{
+ setup: func(b *testing.B, m mapInterface) {
+ if _, ok := m.(*DeepCopyMap); ok {
+ b.Skip("DeepCopyMap has quadratic running time.")
+ }
+ for i := 0; i < hits; i++ {
+ m.LoadOrStore(i, i)
+ }
+ // Prime the map to get it into a steady state.
+ for i := 0; i < hits*2; i++ {
+ m.Load(i % hits)
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ j := i % (hits + misses)
+ if j < hits {
+ if _, ok := m.LoadOrStore(j, i); !ok {
+ b.Fatalf("unexpected miss for %v", j)
+ }
+ } else {
+ if v, loaded := m.LoadOrStore(i, i); loaded {
+ b.Fatalf("failed to store %v: existing value %v", i, v)
+ }
+ }
+ }
+ },
+ })
+}
+
+func BenchmarkLoadOrStoreUnique(b *testing.B) {
+ benchMap(b, bench{
+ setup: func(b *testing.B, m mapInterface) {
+ if _, ok := m.(*DeepCopyMap); ok {
+ b.Skip("DeepCopyMap has quadratic running time.")
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.LoadOrStore(i, i)
+ }
+ },
+ })
+}
+
+func BenchmarkLoadOrStoreCollision(b *testing.B) {
+ benchMap(b, bench{
+ setup: func(_ *testing.B, m mapInterface) {
+ m.LoadOrStore(0, 0)
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.LoadOrStore(0, 0)
+ }
+ },
+ })
+}
+
+func BenchmarkRange(b *testing.B) {
+ const mapSize = 1 << 10
+
+ benchMap(b, bench{
+ setup: func(_ *testing.B, m mapInterface) {
+ for i := 0; i < mapSize; i++ {
+ m.Store(i, i)
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.Range(func(_, _ interface{}) bool { return true })
+ }
+ },
+ })
+}
+
+// BenchmarkAdversarialAlloc tests performance when we store a new value
+// immediately whenever the map is promoted to clean and otherwise load a
+// unique, missing key.
+//
+// This forces the Load calls to always acquire the map's mutex.
+func BenchmarkAdversarialAlloc(b *testing.B) {
+ benchMap(b, bench{
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ var stores, loadsSinceStore int64
+ for ; pb.Next(); i++ {
+ m.Load(i)
+ if loadsSinceStore++; loadsSinceStore > stores {
+ m.LoadOrStore(i, stores)
+ loadsSinceStore = 0
+ stores++
+ }
+ }
+ },
+ })
+}
+
+// BenchmarkAdversarialDelete tests performance when we periodically delete
+// one key and add a different one in a large map.
+//
+// This forces the Load calls to always acquire the map's mutex and periodically
+// makes a full copy of the map despite changing only one entry.
+func BenchmarkAdversarialDelete(b *testing.B) {
+ const mapSize = 1 << 10
+
+ benchMap(b, bench{
+ setup: func(_ *testing.B, m mapInterface) {
+ for i := 0; i < mapSize; i++ {
+ m.Store(i, i)
+ }
+ },
+
+ perG: func(b *testing.B, pb *testing.PB, i int, m mapInterface) {
+ for ; pb.Next(); i++ {
+ m.Load(i)
+
+ if i%mapSize == 0 {
+ var key int
+ m.Range(func(k, _ interface{}) bool {
+ key = k.(int)
+ return false
+ })
+ m.Delete(key)
+ m.Store(i, i)
+ }
+ }
+ },
+ })
+}
--- /dev/null
+// 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()
+ defer m.mu.RUnlock()
+ for k, v := range m.dirty {
+ 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
+}
--- /dev/null
+// 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 (
+ "math/rand"
+ "reflect"
+ "runtime"
+ "sync"
+ "testing"
+ "testing/quick"
+)
+
+type mapOp string
+
+const (
+ opLoad = mapOp("Load")
+ opStore = mapOp("Store")
+ opLoadOrStore = mapOp("LoadOrStore")
+ opDelete = mapOp("Delete")
+)
+
+var mapOps = [...]mapOp{opLoad, opStore, opLoadOrStore, opDelete}
+
+// mapCall is a quick.Generator for calls on mapInterface.
+type mapCall struct {
+ op mapOp
+ k, v interface{}
+}
+
+func (c mapCall) apply(m mapInterface) (interface{}, bool) {
+ switch c.op {
+ case opLoad:
+ return m.Load(c.k)
+ case opStore:
+ m.Store(c.k, c.v)
+ return nil, false
+ case opLoadOrStore:
+ return m.LoadOrStore(c.k, c.v)
+ case opDelete:
+ m.Delete(c.k)
+ return nil, false
+ default:
+ panic("invalid mapOp")
+ }
+}
+
+type mapResult struct {
+ value interface{}
+ ok bool
+}
+
+func randValue(r *rand.Rand) interface{} {
+ b := make([]byte, r.Intn(4))
+ for i := range b {
+ b[i] = 'a' + byte(rand.Intn(26))
+ }
+ return string(b)
+}
+
+func (mapCall) Generate(r *rand.Rand, size int) reflect.Value {
+ c := mapCall{op: mapOps[rand.Intn(len(mapOps))], k: randValue(r)}
+ switch c.op {
+ case opStore, opLoadOrStore:
+ c.v = randValue(r)
+ }
+ return reflect.ValueOf(c)
+}
+
+func applyCalls(m mapInterface, calls []mapCall) (results []mapResult, final map[interface{}]interface{}) {
+ for _, c := range calls {
+ v, ok := c.apply(m)
+ results = append(results, mapResult{v, ok})
+ }
+
+ final = make(map[interface{}]interface{})
+ m.Range(func(k, v interface{}) bool {
+ final[k] = v
+ return true
+ })
+
+ return results, final
+}
+
+func applyMap(calls []mapCall) ([]mapResult, map[interface{}]interface{}) {
+ return applyCalls(new(sync.Map), calls)
+}
+
+func applyRWMutexMap(calls []mapCall) ([]mapResult, map[interface{}]interface{}) {
+ return applyCalls(new(RWMutexMap), calls)
+}
+
+func applyDeepCopyMap(calls []mapCall) ([]mapResult, map[interface{}]interface{}) {
+ return applyCalls(new(DeepCopyMap), calls)
+}
+
+func TestMapMatchesRWMutex(t *testing.T) {
+ if err := quick.CheckEqual(applyMap, applyRWMutexMap, nil); err != nil {
+ t.Error(err)
+ }
+}
+
+func TestMapMatchesDeepCopy(t *testing.T) {
+ if err := quick.CheckEqual(applyMap, applyRWMutexMap, nil); err != nil {
+ t.Error(err)
+ }
+}
+
+func TestConcurrentRange(t *testing.T) {
+ const mapSize = 1 << 10
+
+ m := new(sync.Map)
+ for n := int64(1); n <= mapSize; n++ {
+ m.Store(n, int64(n))
+ }
+
+ done := make(chan struct{})
+ var wg sync.WaitGroup
+ defer func() {
+ close(done)
+ wg.Wait()
+ }()
+ for g := int64(runtime.GOMAXPROCS(0)); g > 0; g-- {
+ r := rand.New(rand.NewSource(g))
+ wg.Add(1)
+ go func(g int64) {
+ defer wg.Done()
+ for i := int64(0); ; i++ {
+ select {
+ case <-done:
+ return
+ default:
+ }
+ for n := int64(1); n < mapSize; n++ {
+ if r.Int63n(mapSize) == 0 {
+ m.Store(n, n*i*g)
+ } else {
+ m.Load(n)
+ }
+ }
+ }
+ }(g)
+ }
+
+ iters := 1 << 10
+ if testing.Short() {
+ iters = 16
+ }
+ for n := iters; n > 0; n-- {
+ seen := make(map[int64]bool, mapSize)
+
+ m.Range(func(ki, vi interface{}) bool {
+ k, v := ki.(int64), vi.(int64)
+ if v%k != 0 {
+ t.Fatalf("while Storing multiples of %v, Range saw value %v", k, v)
+ }
+ if seen[k] {
+ t.Fatalf("Range visited key %v twice", k)
+ }
+ seen[k] = true
+ return true
+ })
+
+ if len(seen) != mapSize {
+ t.Fatalf("Range visited %v elements of %v-element Map", len(seen), mapSize)
+ }
+ }
+}