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source: trunk/sources/HeuristicLab.Problems.ExternalEvaluation/3.3/EvaluationCache.cs @ 10588

Last change on this file since 10588 was 9456, checked in by swagner, 12 years ago

Updated copyright year and added some missing license headers (#1889)

File size: 8.8 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
4 *
5 * This file is part of HeuristicLab.
6 *
7 * HeuristicLab is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation, either version 3 of the License, or
10 * (at your option) any later version.
11 *
12 * HeuristicLab is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
19 *
20 * The LRU cache is based on an idea by Robert Rossney see
21 * <http://csharp-lru-cache.googlecode.com>.
22 */
23#endregion
24
25using System;
26using System.Collections.Generic;
27using System.Globalization;
28using System.IO;
29using System.Linq;
30using System.Text.RegularExpressions;
31using System.Threading;
32using HeuristicLab.Common;
33using HeuristicLab.Common.Resources;
34using HeuristicLab.Core;
35using HeuristicLab.Data;
36using HeuristicLab.Parameters;
37using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
38
39namespace HeuristicLab.Problems.ExternalEvaluation {
40
41  [Item("EvaluationCache", "Cache for external evaluation values")]
42  [StorableClass]
43  public class EvaluationCache : ParameterizedNamedItem {
44
45    #region Types
46    private sealed class CacheEntry {
47
48      public readonly string Key;
49      public double Value;
50
51      public CacheEntry(string key, double value) {
52        Key = key;
53        Value = value;
54      }
55
56      public CacheEntry(string key) {
57        Key = key;
58      }
59
60      public override bool Equals(object obj) {
61        CacheEntry other = obj as CacheEntry;
62        if (other == null)
63          return false;
64        return Key.Equals(other.Key);
65      }
66
67      public override int GetHashCode() {
68        return Key.GetHashCode();
69      }
70
71      public override string ToString() {
72        return string.Format("{{{0} : {1}}}", Key, Value);
73      }
74    }
75
76    public delegate double Evaluator(SolutionMessage message);
77    #endregion
78
79    #region Fields
80    private LinkedList<CacheEntry> list;
81    private Dictionary<CacheEntry, LinkedListNode<CacheEntry>> index;
82
83    private HashSet<string> activeEvaluations = new HashSet<string>();
84    private object cacheLock = new object();
85    #endregion
86
87    #region Properties
88    public static new System.Drawing.Image StaticItemImage {
89      get { return VSImageLibrary.Database; }
90    }
91    public int Size { get { lock (cacheLock) return index.Count; } }
92    public int ActiveEvaluations { get { lock (cacheLock) return activeEvaluations.Count; } }
93
94    [Storable]
95    public int Hits { get; private set; }
96    #endregion
97
98    #region events
99    public event EventHandler Changed;
100
101    protected virtual void OnChanged() {
102      EventHandler handler = Changed;
103      if (handler != null)
104        handler(this, EventArgs.Empty);
105    }
106    #endregion
107
108    #region Parameters
109    public FixedValueParameter<IntValue> CapacityParameter {
110      get { return (FixedValueParameter<IntValue>)Parameters["Capacity"]; }
111    }
112    public FixedValueParameter<BoolValue> PersistentCacheParameter {
113      get { return (FixedValueParameter<BoolValue>)Parameters["PersistentCache"]; }
114    }
115    #endregion
116
117    #region Parameter Values
118    public int Capacity {
119      get { return CapacityParameter.Value.Value; }
120      set { CapacityParameter.Value.Value = value; }
121    }
122    public bool IsPersistent {
123      get { return PersistentCacheParameter.Value.Value; }
124    }
125    #endregion
126
127    #region Persistence
128    [Storable(Name = "Cache")]
129    private IEnumerable<KeyValuePair<string, double>> Cache_Persistence {
130      get {
131        if (IsPersistent) {
132          return GetCacheValues();
133        } else {
134          return Enumerable.Empty<KeyValuePair<string, double>>();
135        }
136      }
137      set {
138        SetCacheValues(value);
139      }
140    }
141    [StorableHook(HookType.AfterDeserialization)]
142    private void AfterDeserialization() {
143      RegisterEvents();
144    }
145    #endregion
146
147    #region Construction & Cloning
148    [StorableConstructor]
149    protected EvaluationCache(bool deserializing) : base(deserializing) { }
150    protected EvaluationCache(EvaluationCache original, Cloner cloner)
151      : base(original, cloner) {
152      SetCacheValues(original.GetCacheValues());
153      Hits = original.Hits;
154      RegisterEvents();
155    }
156    public EvaluationCache() {
157      list = new LinkedList<CacheEntry>();
158      index = new Dictionary<CacheEntry, LinkedListNode<CacheEntry>>();
159      Parameters.Add(new FixedValueParameter<IntValue>("Capacity", "Maximum number of cache entries.", new IntValue(10000)));
160      Parameters.Add(new FixedValueParameter<BoolValue>("PersistentCache", "Save cache when serializing object graph?", new BoolValue(false)));
161      RegisterEvents();
162    }
163    public override IDeepCloneable Clone(Cloner cloner) {
164      return new EvaluationCache(this, cloner);
165    }
166    #endregion
167
168    #region Event Handling
169    private void RegisterEvents() {
170      CapacityParameter.Value.ValueChanged += new EventHandler(CapacityChanged);
171    }
172
173    void CapacityChanged(object sender, EventArgs e) {
174      if (Capacity < 0)
175        throw new ArgumentOutOfRangeException("Cache capacity cannot be less than zero");
176      lock (cacheLock)
177        Trim();
178      OnChanged();
179    }
180    #endregion
181
182    #region Methods
183    public void Reset() {
184      lock (cacheLock) {
185        list = new LinkedList<CacheEntry>();
186        index = new Dictionary<CacheEntry, LinkedListNode<CacheEntry>>();
187        Hits = 0;
188      }
189      OnChanged();
190    }
191
192    public double GetValue(SolutionMessage message, Evaluator evaluate) {
193      var entry = new CacheEntry(message.ToString());
194      bool lockTaken = false;
195      bool waited = false;
196      try {
197        Monitor.Enter(cacheLock, ref lockTaken);
198        while (true) {
199          LinkedListNode<CacheEntry> node;
200          if (index.TryGetValue(entry, out node)) {
201            list.Remove(node);
202            list.AddLast(node);
203            Hits++;
204            lockTaken = false;
205            Monitor.Exit(cacheLock);
206            OnChanged();
207            return node.Value.Value;
208          } else {
209            if (!waited && activeEvaluations.Contains(entry.Key)) {
210              while (activeEvaluations.Contains(entry.Key))
211                Monitor.Wait(cacheLock);
212              waited = true;
213            } else {
214              activeEvaluations.Add(entry.Key);
215              lockTaken = false;
216              Monitor.Exit(cacheLock);
217              OnChanged();
218              try {
219                entry.Value = evaluate(message);
220                Monitor.Enter(cacheLock, ref lockTaken);
221                index[entry] = list.AddLast(entry);
222                Trim();
223              }
224              finally {
225                if (!lockTaken)
226                  Monitor.Enter(cacheLock, ref lockTaken);
227                activeEvaluations.Remove(entry.Key);
228                Monitor.PulseAll(cacheLock);
229                lockTaken = false;
230                Monitor.Exit(cacheLock);
231              }
232              OnChanged();
233              return entry.Value;
234            }
235          }
236        }
237      }
238      finally {
239        if (lockTaken)
240          Monitor.Exit(cacheLock);
241      }
242    }
243
244    private void Trim() {
245      while (list.Count > Capacity) {
246        var item = list.First;
247        list.Remove(item);
248        index.Remove(item.Value);
249      }
250    }
251
252    private IEnumerable<KeyValuePair<string, double>> GetCacheValues() {
253      lock (cacheLock) {
254        return index.ToDictionary(kvp => kvp.Key.Key, kvp => kvp.Key.Value);
255      }
256    }
257
258    private void SetCacheValues(IEnumerable<KeyValuePair<string, double>> value) {
259      lock (cacheLock) {
260        list = new LinkedList<CacheEntry>();
261        index = new Dictionary<CacheEntry, LinkedListNode<CacheEntry>>();
262        foreach (var kvp in value) {
263          var entry = new CacheEntry(kvp.Key) { Value = kvp.Value };
264          index[entry] = list.AddLast(entry);
265        }
266      }
267    }
268
269    public void Save(string filename) {
270      using (var writer = new StreamWriter(filename)) {
271        lock (cacheLock) {
272          foreach (var entry in list) {
273            writer.WriteLine(string.Format(CultureInfo.InvariantCulture,
274              "\"{0}\", {1}",
275              Regex.Replace(entry.Key, "\\s", "").Replace("\"", "\"\""),
276              entry.Value));
277          }
278        }
279        writer.Close();
280      }
281    }
282    #endregion
283  }
284}
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