Barak Michener
3f391a782c
Subcommits: implement iterator and remove ResultTree add Err() to sql remove redundant and less helpful indices, change fillfactor, and use COPY FROM
63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
// Copyright 2014 The Cayley Authors. All rights reserved.
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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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package sql
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import (
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"container/list"
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)
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// cache implements an LRU cache.
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type cache struct {
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cache map[string]*list.Element
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priority *list.List
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maxSize int
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}
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type kv struct {
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key string
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value int64
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}
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func newCache(size int) *cache {
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var lru cache
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lru.maxSize = size
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lru.priority = list.New()
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lru.cache = make(map[string]*list.Element)
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return &lru
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}
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func (lru *cache) Put(key string, value int64) {
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if _, ok := lru.Get(key); ok {
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return
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}
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if len(lru.cache) == lru.maxSize {
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lru.removeOldest()
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}
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lru.priority.PushFront(kv{key: key, value: value})
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lru.cache[key] = lru.priority.Front()
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}
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func (lru *cache) Get(key string) (int64, bool) {
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if element, ok := lru.cache[key]; ok {
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lru.priority.MoveToFront(element)
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return element.Value.(kv).value, true
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}
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return 0, false
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}
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func (lru *cache) removeOldest() {
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last := lru.priority.Remove(lru.priority.Back())
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delete(lru.cache, last.(kv).key)
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}
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