Cache count

src/neo/IO/Caching/HashSetCache.cs

@@ -6,6 +6,11 @@ namespace Neo.IO.Caching
 {
  public class HashSetCache<T> : IReadOnlyCollection<T> where T : IEquatable<T>
  {
+ /// <summary>
+ /// Cached count
+ /// </summary> 
+ private int _count = -1;
+
  /// <summary>
  /// Sets where the Hashes are stored
  /// </summary> 
@@ -25,12 +30,13 @@ public int Count
  {
  get
  {
- int count = 0;
+ if (_count != -1) return _count;
+ _count = 0;
  foreach (var set in sets)
  {
- count += set.Count;
+ _count += set.Count;
  }
- return count;
+ return _count;
  }
  }
 
@@ -47,6 +53,7 @@ public HashSetCache(int bucketCapacity, int maxBucketCount = 10)
  public bool Add(T item)
  {
  if (Contains(item)) return false;
+ _count = -1;
  if (sets.First.Value.Count < bucketCapacity) return sets.First.Value.Add(item);
  var newSet = new HashSet<T>
  {
@@ -72,7 +79,11 @@ public void ExceptWith(IEnumerable<T> items)
  {
  foreach (var set in sets)
  {
- if (set.Remove(item)) break;
+ if (set.Remove(item))
+ {
+ _count = -1;
+ break;
+ }
  }
  }
  }