145 lines
3.6 KiB
C#
145 lines
3.6 KiB
C#
//
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// A simple LRU cache
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//
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// Authors:
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// Miguel de Icaza (miguel@gnome.org)
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// Andres G. Aragoneses (andres@7digital.com)
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//
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// Copyright 2010 Miguel de Icaza
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// Copyright 2013 7digital Media Ltd.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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using System;
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using System.Collections.Generic;
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namespace System.Web.Configuration {
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class LruCache<TKey, TValue> {
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Dictionary<TKey, LinkedListNode <TValue>> dict;
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Dictionary<LinkedListNode<TValue>, TKey> revdict;
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LinkedList<TValue> list;
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int entry_limit;
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bool eviction_warning_shown;
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int evictions;
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bool size_overriden;
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internal string EvictionWarning { set; private get; }
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public LruCache (int entryLimit)
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{
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entry_limit = entryLimit;
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dict = new Dictionary<TKey, LinkedListNode<TValue>> ();
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revdict = new Dictionary<LinkedListNode<TValue>, TKey> ();
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list = new LinkedList<TValue> ();
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}
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//for debugging: public int Count { get { return dict.Count; } }
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void Evict ()
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{
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var last = list.Last;
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if (last == null)
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return;
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var key = revdict [last];
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dict.Remove (key);
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revdict.Remove (last);
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list.RemoveLast ();
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DisposeValue (last.Value);
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evictions++;
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if (!String.IsNullOrEmpty (EvictionWarning) && !eviction_warning_shown && (evictions >= entry_limit)) {
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Console.Error.WriteLine ("WARNING: " + EvictionWarning);
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eviction_warning_shown = true;
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}
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}
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public void Clear ()
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{
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foreach (var element in list) {
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DisposeValue (element);
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}
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dict.Clear ();
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revdict.Clear ();
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list.Clear ();
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eviction_warning_shown = false;
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evictions = 0;
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}
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void DisposeValue (TValue value)
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{
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if (value is IDisposable) {
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((IDisposable)value).Dispose ();
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}
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}
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public bool TryGetValue (TKey key, out TValue value)
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{
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LinkedListNode<TValue> node;
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if (dict.TryGetValue (key, out node)){
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list.Remove (node);
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list.AddFirst (node);
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value = node.Value;
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return true;
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}
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value = default (TValue);
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return false;
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}
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public void Add (TKey key, TValue value)
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{
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LinkedListNode<TValue> node;
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if (dict.TryGetValue (key, out node)){
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// If we already have a key, move it to the front
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list.Remove (node);
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list.AddFirst (node);
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// Remove the old value
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DisposeValue (node.Value);
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node.Value = value;
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return;
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}
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if (dict.Count >= entry_limit)
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Evict ();
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// Adding new node
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node = new LinkedListNode<TValue> (value);
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list.AddFirst (node);
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dict [key] = node;
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revdict [node] = key;
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}
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public override string ToString ()
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{
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return "LRUCache dict={0} revdict={1} list={2}";
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}
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}
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}
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