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refactor: upgrade to go1.20 in ConcurrentMap
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reugn committed Oct 27, 2023
1 parent dfaa9bc commit 03b3716
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Showing 2 changed files with 15 additions and 34 deletions.
35 changes: 15 additions & 20 deletions concurrent_map.go
Original file line number Diff line number Diff line change
Expand Up @@ -16,17 +16,16 @@ import (
// sets of keys. In these two cases, use of a sync.Map may significantly reduce lock
// contention compared to a Go map paired with a separate sync.Mutex or sync.RWMutex.
type ConcurrentMap[K comparable, V any] struct {
m *atomic.Value // TODO: use atomic.Pointer when upgrading to/past go1.19
size int64
clearing int32 // TODO: use atomic.Bool when upgrading to/past go1.19
_ noCopy
m *atomic.Pointer[sync.Map]
size atomic.Int64
clearing atomic.Bool
}

var _ Map[int, any] = (*ConcurrentMap[int, any])(nil)

// NewConcurrentMap returns a new ConcurrentMap instance.
func NewConcurrentMap[K comparable, V any]() *ConcurrentMap[K, V] {
var underlying atomic.Value
var underlying atomic.Pointer[sync.Map]
underlying.Store(&sync.Map{})
return &ConcurrentMap[K, V]{
m: &underlying,
Expand All @@ -35,10 +34,10 @@ func NewConcurrentMap[K comparable, V any]() *ConcurrentMap[K, V] {

// Clear removes all of the mappings from this map.
func (cm *ConcurrentMap[K, V]) Clear() {
atomic.StoreInt32(&cm.clearing, 1)
defer atomic.StoreInt32(&cm.clearing, 0)
_ = cm.m.Swap(&sync.Map{})
atomic.StoreInt64(&cm.size, 0)
cm.clearing.Store(true)
defer cm.clearing.Store(false)
cm.m.Store(&sync.Map{})
cm.size.Store(0)
}

// ComputeIfAbsent attempts to compute a value using the given mapping
Expand All @@ -49,7 +48,7 @@ func (cm *ConcurrentMap[K, V]) ComputeIfAbsent(key K, mappingFunction func(K) *V
if value == nil {
computed, loaded := cm.smap().LoadOrStore(key, mappingFunction(key))
if !loaded {
atomic.AddInt64(&cm.size, 1)
cm.size.Add(1)
}
return computed.(*V)
}
Expand Down Expand Up @@ -100,12 +99,9 @@ func (cm *ConcurrentMap[K, V]) KeySet() []K {

// Put associates the specified value with the specified key in this map.
func (cm *ConcurrentMap[K, V]) Put(key K, value *V) {
// TODO: use sync.Map.Swap when upgrading to/past go1.20
_, loaded := cm.smap().LoadOrStore(key, value)
_, loaded := cm.smap().Swap(key, value)
if !loaded {
atomic.AddInt64(&cm.size, 1)
} else {
cm.smap().Store(key, value)
cm.size.Add(1)
}
}

Expand All @@ -116,13 +112,13 @@ func (cm *ConcurrentMap[K, V]) Remove(key K) *V {
if !loaded {
return nil
}
atomic.AddInt64(&cm.size, -1)
cm.size.Add(-1)
return value.(*V)
}

// Size returns the number of key-value mappings in this map.
func (cm *ConcurrentMap[K, V]) Size() int {
size := atomic.LoadInt64(&cm.size)
size := cm.size.Load()
if size > 0 {
return int(size)
}
Expand All @@ -142,11 +138,10 @@ func (cm *ConcurrentMap[K, V]) Values() []*V {

func (cm *ConcurrentMap[K, V]) smap() *sync.Map {
for {
c := atomic.LoadInt32(&cm.clearing)
if c == 0 {
if !cm.clearing.Load() {
break
}
time.Sleep(time.Nanosecond)
}
return cm.m.Load().(*sync.Map)
return cm.m.Load()
}
14 changes: 0 additions & 14 deletions no_copy.go

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