hugo evictingqueue 代码
文件路径：/common/types/evictingqueue.go
/ Copyright 2017-present The Hugo Authors. All rights reserved.
/
/ 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 types contains types shared between packages in Hugo.
package types
import (
"sync"
)
/ EvictingStringQueue is a queue which automatically evicts elements from the head of
/ the queue when attempting to add new elements onto the queue and it is full.
/ This queue orders elements LIFO (last-in-first-out). It throws away duplicates.
/ Note: This queue currently does not contain any remove (poll etc.) methods.
type EvictingStringQueue struct {
size int
vals []string
set map[string]bool
mu sync.Mutex
}
/ NewEvictingStringQueue creates a new queue with the given size.
func NewEvictingStringQueue(size int) *EvictingStringQueue {
return &EvictingStringQueue{size: size, set: make(map[string]bool)}
}
/ Add adds a new string to the tail of the queue if it's not already there.
func (q *EvictingStringQueue) Add(v string) {
q.mu.Lock()
if q.set[v] {
q.mu.Unlock()
return
}
if len(q.set) == q.size {
/ Full
delete(q.set, q.vals[0])
q.vals = append(q.vals[:0], q.vals[1:]...)
}
q.set[v] = true
q.vals = append(q.vals, v)
q.mu.Unlock()
}
/ Contains returns whether the queue contains v.
func (q *EvictingStringQueue) Contains(v string) bool {
q.mu.Lock()
defer q.mu.Unlock()
return q.set[v]
}
/ Peek looks at the last element added to the queue.
func (q *EvictingStringQueue) Peek() string {
q.mu.Lock()
l := len(q.vals)
if l == 0 {
q.mu.Unlock()
return ""
}
elem := q.vals[l-1]
q.mu.Unlock()
return elem
}
/ PeekAll looks at all the elements in the queue, with the newest first.
func (q *EvictingStringQueue) PeekAll() []string {
q.mu.Lock()
vals := make([]string, len(q.vals))
copy(vals, q.vals)
q.mu.Unlock()
for i, j := 0, len(vals)-1; i < j; i, j = i+1, j-1 {
vals[i], vals[j] = vals[j], vals[i]
}
return vals
}
/ PeekAllSet returns PeekAll as a set.
func (q *EvictingStringQueue) PeekAllSet() map[string]bool {
all := q.PeekAll()
set := make(map[string]bool)
for _, v := range all {
set[v] = true
}
return set
}