mirror of
https://github.com/golang/go
synced 2024-11-23 17:50:06 -07:00
sync: import Map from x/sync/syncmap
This is a direct port of the version from commit a60ad46e0ed33d02e09bda439efaf9c9727dbc6c (https://go-review.googlesource.com/c/37342/). updates #17973 updates #18177 Change-Id: I63fa5ef6951b1edd39f84927d1181a4df9b15385 Reviewed-on: https://go-review.googlesource.com/36617 Reviewed-by: Russ Cox <rsc@golang.org> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Bryan C. Mills
Bryan Mills
parent
e1a7db7f3b
commit
959025c0ac
367
src/sync/map.go
Normal file
367
src/sync/map.go
Normal file
@ -0,0 +1,367 @@
|
||||
// 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
|
||||
}
|
||||
217
src/sync/map_bench_test.go
Normal file
217
src/sync/map_bench_test.go
Normal file
@ -0,0 +1,217 @@
|
||||
// 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)
|
||||
}
|
||||
}
|
||||
},
|
||||
})
|
||||
}
|
||||
142
src/sync/map_reference_test.go
Normal file
142
src/sync/map_reference_test.go
Normal file
@ -0,0 +1,142 @@
|
||||
// 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
|
||||
}
|
||||
170
src/sync/map_test.go
Normal file
170
src/sync/map_test.go
Normal file
@ -0,0 +1,170 @@
|
||||
// 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)
|
||||
}
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user