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// Copyright 2018 The etcd Authors
//
// 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 lease
import "container/heap"
// LeaseWithTime contains lease object with a time.
// For the lessor's lease heap, time identifies the lease expiration time.
// For the lessor's lease checkpoint heap, the time identifies the next lease checkpoint time.
type LeaseWithTime struct {
id LeaseID
// Unix nanos timestamp.
time int64
index int
}
type LeaseQueue []*LeaseWithTime
func (pq LeaseQueue) Len() int { return len(pq) }
func (pq LeaseQueue) Less(i, j int) bool {
return pq[i].time < pq[j].time
}
func (pq LeaseQueue) Swap(i, j int) {
pq[i], pq[j] = pq[j], pq[i]
pq[i].index = i
pq[j].index = j
}
func (pq *LeaseQueue) Push(x interface{}) {
n := len(*pq)
item := x.(*LeaseWithTime)
item.index = n
*pq = append(*pq, item)
}
func (pq *LeaseQueue) Pop() interface{} {
old := *pq
n := len(old)
item := old[n-1]
item.index = -1 // for safety
*pq = old[0 : n-1]
return item
}
// LeaseExpiredNotifier is a queue used to notify lessor to revoke expired lease.
// Only save one item for a lease, `Register` will update time of the corresponding lease.
type LeaseExpiredNotifier struct {
m map[LeaseID]*LeaseWithTime
queue LeaseQueue
}
func newLeaseExpiredNotifier() *LeaseExpiredNotifier {
return &LeaseExpiredNotifier{
m: make(map[LeaseID]*LeaseWithTime),
queue: make(LeaseQueue, 0),
}
}
func (mq *LeaseExpiredNotifier) Init() {
heap.Init(&mq.queue)
mq.m = make(map[LeaseID]*LeaseWithTime)
for _, item := range mq.queue {
mq.m[item.id] = item
}
}
func (mq *LeaseExpiredNotifier) RegisterOrUpdate(item *LeaseWithTime) {
if old, ok := mq.m[item.id]; ok {
old.time = item.time
heap.Fix(&mq.queue, old.index)
} else {
heap.Push(&mq.queue, item)
mq.m[item.id] = item
}
}
func (mq *LeaseExpiredNotifier) Unregister() *LeaseWithTime {
item := heap.Pop(&mq.queue).(*LeaseWithTime)
delete(mq.m, item.id)
return item
}
func (mq *LeaseExpiredNotifier) Poll() *LeaseWithTime {
if mq.Len() == 0 {
return nil
}
return mq.queue[0]
}
func (mq *LeaseExpiredNotifier) Len() int {
return len(mq.m)
}