1// Copyright 2019, OpenCensus Authors 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 15package trace 16 17import ( 18 "github.com/golang/groupcache/lru" 19) 20 21// A simple lru.Cache wrapper that tracks the keys of the current contents and 22// the cumulative number of evicted items. 23type lruMap struct { 24 cacheKeys map[lru.Key]bool 25 cache *lru.Cache 26 droppedCount int 27} 28 29func newLruMap(size int) *lruMap { 30 lm := &lruMap{ 31 cacheKeys: make(map[lru.Key]bool), 32 cache: lru.New(size), 33 droppedCount: 0, 34 } 35 lm.cache.OnEvicted = func(key lru.Key, value interface{}) { 36 delete(lm.cacheKeys, key) 37 lm.droppedCount++ 38 } 39 return lm 40} 41 42func (lm lruMap) len() int { 43 return lm.cache.Len() 44} 45 46func (lm lruMap) keys() []interface{} { 47 keys := make([]interface{}, len(lm.cacheKeys)) 48 for k := range lm.cacheKeys { 49 keys = append(keys, k) 50 } 51 return keys 52} 53 54func (lm *lruMap) add(key, value interface{}) { 55 lm.cacheKeys[lru.Key(key)] = true 56 lm.cache.Add(lru.Key(key), value) 57} 58 59func (lm *lruMap) get(key interface{}) (interface{}, bool) { 60 return lm.cache.Get(key) 61} 62