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98 lines
2.3 KiB
98 lines
2.3 KiB
6 years ago
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/*
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*
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* Copyright 2018 gRPC authors.
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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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*/
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package grpc
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import (
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"container/list"
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)
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type linkedMapKVPair struct {
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key string
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value *stickyStoreEntry
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}
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// linkedMap is an implementation of a map that supports removing the oldest
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// entry.
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//
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// linkedMap is NOT thread safe.
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//
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// It's for use of stickiness only!
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type linkedMap struct {
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m map[string]*list.Element
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l *list.List // Head of the list is the oldest element.
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}
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// newLinkedMap returns a new LinkedMap.
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func newLinkedMap() *linkedMap {
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return &linkedMap{
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m: make(map[string]*list.Element),
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l: list.New(),
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}
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}
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// put adds entry (key, value) to the map. Existing key will be overridden.
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func (m *linkedMap) put(key string, value *stickyStoreEntry) {
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if oldE, ok := m.m[key]; ok {
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// Remove existing entry.
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m.l.Remove(oldE)
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}
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e := m.l.PushBack(&linkedMapKVPair{key: key, value: value})
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m.m[key] = e
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}
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// get returns the value of the given key.
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func (m *linkedMap) get(key string) (*stickyStoreEntry, bool) {
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e, ok := m.m[key]
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if !ok {
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return nil, false
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}
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m.l.MoveToBack(e)
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return e.Value.(*linkedMapKVPair).value, true
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}
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// remove removes key from the map, and returns the value. The map is not
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// modified if key is not in the map.
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func (m *linkedMap) remove(key string) (*stickyStoreEntry, bool) {
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e, ok := m.m[key]
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if !ok {
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return nil, false
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}
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delete(m.m, key)
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m.l.Remove(e)
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return e.Value.(*linkedMapKVPair).value, true
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}
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// len returns the len of the map.
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func (m *linkedMap) len() int {
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return len(m.m)
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}
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// clear removes all elements from the map.
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func (m *linkedMap) clear() {
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m.m = make(map[string]*list.Element)
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m.l = list.New()
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}
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// removeOldest removes the oldest key from the map.
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func (m *linkedMap) removeOldest() {
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e := m.l.Front()
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m.l.Remove(e)
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delete(m.m, e.Value.(*linkedMapKVPair).key)
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}
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