96 lines
2.4 KiB
Go
96 lines
2.4 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package executorinfo
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import (
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"container/list"
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"errors"
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"github.com/mesos/mesos-go/mesosproto"
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)
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// Cache is an LRU cache for executor info objects.
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// It is not safe for concurrent use.
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type Cache struct {
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maxEntries int
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ll *list.List
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cache map[string]*list.Element // by hostname
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}
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type entry struct {
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hostname string
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info *mesosproto.ExecutorInfo
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}
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// NewCache creates a new cache.
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// If maxEntries is zero, an error is being returned.
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func NewCache(maxEntries int) (*Cache, error) {
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if maxEntries <= 0 {
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return nil, errors.New("invalid maxEntries value")
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}
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return &Cache{
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maxEntries: maxEntries,
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ll: list.New(), // least recently used sorted linked list
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cache: make(map[string]*list.Element),
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}, nil
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}
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// Add adds an executor info associated with the given hostname to the cache.
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func (c *Cache) Add(hostname string, e *mesosproto.ExecutorInfo) {
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if ee, ok := c.cache[hostname]; ok {
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c.ll.MoveToFront(ee)
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ee.Value.(*entry).info = e
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return
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}
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el := c.ll.PushFront(&entry{hostname, e})
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c.cache[hostname] = el
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if c.ll.Len() > c.maxEntries {
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c.RemoveOldest()
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}
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}
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// Get looks up a hostname's executor info from the cache.
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func (c *Cache) Get(hostname string) (e *mesosproto.ExecutorInfo, ok bool) {
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if el, hit := c.cache[hostname]; hit {
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c.ll.MoveToFront(el)
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return el.Value.(*entry).info, true
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}
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return
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}
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// Remove removes the provided hostname from the cache.
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func (c *Cache) Remove(hostname string) {
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if el, hit := c.cache[hostname]; hit {
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c.removeElement(el)
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}
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}
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// RemoveOldest removes the oldest item from the cache.
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func (c *Cache) RemoveOldest() {
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oldest := c.ll.Back()
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if oldest != nil {
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c.removeElement(oldest)
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}
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}
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func (c *Cache) removeElement(el *list.Element) {
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c.ll.Remove(el)
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kv := el.Value.(*entry)
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delete(c.cache, kv.hostname)
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}
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