Initial

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

vendor/go.opencensus.io/trace/lrumap.go

@@ -0,0 +1,61 @@
+// Copyright 2019, OpenCensus 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 trace
+
+import (
+	"github.com/golang/groupcache/lru"
+)
+
+// A simple lru.Cache wrapper that tracks the keys of the current contents and
+// the cumulative number of evicted items.
+type lruMap struct {
+	cacheKeys    map[lru.Key]bool
+	cache        *lru.Cache
+	droppedCount int
+}
+
+func newLruMap(size int) *lruMap {
+	lm := &lruMap{
+		cacheKeys:    make(map[lru.Key]bool),
+		cache:        lru.New(size),
+		droppedCount: 0,
+	}
+	lm.cache.OnEvicted = func(key lru.Key, value interface{}) {
+		delete(lm.cacheKeys, key)
+		lm.droppedCount++
+	}
+	return lm
+}
+
+func (lm lruMap) len() int {
+	return lm.cache.Len()
+}
+
+func (lm lruMap) keys() []interface{} {
+	keys := []interface{}{}
+	for k := range lm.cacheKeys {
+		keys = append(keys, k)
+	}
+	return keys
+}
+
+func (lm *lruMap) add(key, value interface{}) {
+	lm.cacheKeys[lru.Key(key)] = true
+	lm.cache.Add(lru.Key(key), value)
+}
+
+func (lm *lruMap) get(key interface{}) (interface{}, bool) {
+	return lm.cache.Get(key)
+}