github.com/livekit/protocol@v1.16.1-0.20240517185851-47e4c6bba773/utils/timeoutqueue.go (about)

     1  // Copyright 2023 LiveKit, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package utils
    16  
    17  import (
    18  	"sync"
    19  	"time"
    20  )
    21  
    22  type TimeoutQueueItem[T any] struct {
    23  	Value      T
    24  	time       int64
    25  	next, prev *TimeoutQueueItem[T]
    26  	removed    bool
    27  }
    28  
    29  type TimeoutQueue[T any] struct {
    30  	mu         sync.Mutex
    31  	head, tail *TimeoutQueueItem[T]
    32  }
    33  
    34  func (q *TimeoutQueue[T]) Reset(i *TimeoutQueueItem[T]) bool {
    35  	t := time.Now().UnixNano()
    36  
    37  	q.mu.Lock()
    38  	defer q.mu.Unlock()
    39  
    40  	if !i.removed {
    41  		i.time = t
    42  		q.remove(i)
    43  		q.push(i)
    44  	}
    45  	return !i.removed
    46  }
    47  
    48  func (q *TimeoutQueue[T]) Remove(i *TimeoutQueueItem[T]) {
    49  	q.mu.Lock()
    50  	defer q.mu.Unlock()
    51  
    52  	i.removed = true
    53  	q.remove(i)
    54  }
    55  
    56  func (q *TimeoutQueue[T]) popBefore(t time.Time, remove bool) *TimeoutQueueItem[T] {
    57  	q.mu.Lock()
    58  	defer q.mu.Unlock()
    59  
    60  	i := q.head
    61  	if i == nil || i.time > t.UnixNano() {
    62  		return nil
    63  	}
    64  
    65  	i.removed = i.removed || remove
    66  	i.time = 0
    67  	q.remove(i)
    68  
    69  	return i
    70  }
    71  
    72  func (q *TimeoutQueue[T]) push(i *TimeoutQueueItem[T]) {
    73  	i.prev = q.tail
    74  	i.next = nil
    75  
    76  	if i.prev != nil {
    77  		i.prev.next = i
    78  	}
    79  
    80  	q.tail = i
    81  	if q.head == nil {
    82  		q.head = i
    83  	}
    84  }
    85  
    86  func (q *TimeoutQueue[T]) remove(i *TimeoutQueueItem[T]) {
    87  	if q.tail == i {
    88  		q.tail = i.prev
    89  	}
    90  	if q.head == i {
    91  		q.head = i.next
    92  	}
    93  	if i.prev != nil {
    94  		i.prev.next = i.next
    95  	}
    96  	if i.next != nil {
    97  		i.next.prev = i.prev
    98  	}
    99  	i.next = nil
   100  	i.prev = nil
   101  }
   102  
   103  func (q *TimeoutQueue[T]) IterateAfter(timeout time.Duration) timeoutQueueIterator[T] {
   104  	return newTimeoutQueueIterator(q, timeout, false)
   105  }
   106  
   107  func (q *TimeoutQueue[T]) IterateRemoveAfter(timeout time.Duration) timeoutQueueIterator[T] {
   108  	return newTimeoutQueueIterator(q, timeout, true)
   109  }
   110  
   111  type timeoutQueueIterator[T any] struct {
   112  	q      *TimeoutQueue[T]
   113  	time   time.Time
   114  	remove bool
   115  	item   *TimeoutQueueItem[T]
   116  }
   117  
   118  func newTimeoutQueueIterator[T any](q *TimeoutQueue[T], timeout time.Duration, remove bool) timeoutQueueIterator[T] {
   119  	return timeoutQueueIterator[T]{
   120  		q:      q,
   121  		time:   time.Now().Add(-timeout),
   122  		remove: remove,
   123  	}
   124  }
   125  
   126  func (i *timeoutQueueIterator[T]) Next() bool {
   127  	i.item = i.q.popBefore(i.time, i.remove)
   128  	return i.item != nil
   129  }
   130  
   131  func (i *timeoutQueueIterator[T]) Item() *TimeoutQueueItem[T] {
   132  	return i.item
   133  }