forked from johnjohnsp1/capsule8
/
subscription.go
97 lines (80 loc) · 2.06 KB
/
subscription.go
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// Copyright 2017 Capsule8, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sensor
import (
"sync"
"sync/atomic"
)
type subscriptionUnregisterFn func(eventID uint64, sub *subscription)
type subscription struct {
data chan interface{}
unregister subscriptionUnregisterFn
}
//
// safeSubscriptionMap
// map[uint64]chan interface{}
//
type subscriptionMap map[uint64]*subscription
func newSubscriptionMap() subscriptionMap {
return make(subscriptionMap)
}
type safeSubscriptionMap struct {
sync.Mutex // used only by writers
active atomic.Value // map[uint64]chan interface{}
}
func newSafeSubscriptionMap() *safeSubscriptionMap {
return &safeSubscriptionMap{}
}
func (m *safeSubscriptionMap) getMap() subscriptionMap {
value := m.active.Load()
if value == nil {
return nil
}
return value.(subscriptionMap)
}
func (m *safeSubscriptionMap) remove(mfrom subscriptionMap) {
m.Lock()
defer m.Unlock()
r := make(subscriptionMap, len(mfrom))
om := m.getMap()
if om != nil {
nm := make(subscriptionMap, len(om)-len(mfrom))
for k, v := range om {
if _, ok := mfrom[k]; !ok {
nm[k] = v
} else if v.unregister != nil {
r[k] = v
}
}
m.active.Store(nm)
}
for eventID, eventSub := range r {
eventSub.unregister(eventID, eventSub)
}
}
func (m *safeSubscriptionMap) update(mfrom subscriptionMap) {
m.Lock()
defer m.Unlock()
om := m.getMap()
nm := make(subscriptionMap, len(om)+len(mfrom))
if om != nil {
for k, v := range om {
nm[k] = v
}
}
for k, v := range mfrom {
nm[k] = v
}
m.active.Store(nm)
}