浅谈C#在网络波动时防重复提交的方法

public class Cache<TKey, TValue>  {    private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();    private readonly Dictionary<TKey, TValue> _map = new Dictionary<TKey, TValue>();    public int Count {      get { return _map.Count; }    }    public TValue Execute(TKey key, Func<TValue> factory)    {      // Check cache      _lock.EnterReadLock();      TValue val;      try {        if (_map.TryGetValue(key, out val))          return val;      } finally {        _lock.ExitReadLock();      }      // Cache it      _lock.EnterWriteLock();      try {        // Check again        if (_map.TryGetValue(key, out val))          return val;        // Create it        val = factory();        // Store it        _map.Add(key, val);        // Done        return val;      } finally {        _lock.ExitWriteLock();      }    }    public void Clear()    {      // Cache it      _lock.EnterWriteLock();      try {        _map.Clear();      } finally {        _lock.ExitWriteLock();      }    }  }

/// <summary>  /// 防重复缓存  /// </summary>  /// <typeparam name="TKey"></typeparam>  /// <typeparam name="TValue"></typeparam>  public class AntiDupCache<TKey, TValue>  {    private readonly int _maxCount;//缓存最高数量    private readonly long _expireTicks;//超时 Ticks    private long _lastTicks;//最后Ticks    private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim();    private readonly ReaderWriterLockSlim _slimLock = new ReaderWriterLockSlim();    private readonly Dictionary<TKey, Tuple<long, TValue>> _map = new Dictionary<TKey, Tuple<long, TValue>>();    private readonly Dictionary<TKey, AntiDupLockSlim> _lockDict = new Dictionary<TKey, AntiDupLockSlim>();    private readonly Queue<TKey> _queue = new Queue<TKey>();    class AntiDupLockSlim : ReaderWriterLockSlim { public int UseCount; }    /// <summary>    /// 防重复缓存    /// </summary>    /// <param name="maxCount">缓存最高数量,0 不缓存，-1 缓存所有</param>    /// <param name="expireSecond">超时秒数,0 不缓存，-1 永久缓存 </param>    public AntiDupCache(int maxCount = 100, int expireSecond = 1)    {      if (maxCount < 0) {        _maxCount = -1;      } else {        _maxCount = maxCount;      }      if (expireSecond < 0) {        _expireTicks = -1;      } else {        _expireTicks = expireSecond * TimeSpan.FromSeconds(1).Ticks;      }    }    /// <summary>    /// 个数    /// </summary>    public int Count {      get { return _map.Count; }    }    /// <summary>    /// 执行    /// </summary>    /// <param name="key">值</param>    /// <param name="factory">执行方法</param>    /// <returns></returns>    public TValue Execute(TKey key, Func<TValue> factory)    {      // 过期时间为0 则不缓存      if (object.Equals(null, key) || _expireTicks == 0L || _maxCount == 0) { return factory(); }      Tuple<long, TValue> tuple;      long lastTicks;      _lock.EnterReadLock();      try {        if (_map.TryGetValue(key, out tuple)) {          if (_expireTicks == -1) return tuple.Item2;          if (tuple.Item1 + _expireTicks > DateTime.Now.Ticks) return tuple.Item2;        }        lastTicks = _lastTicks;      } finally { _lock.ExitReadLock(); }      AntiDupLockSlim slim;      _slimLock.EnterUpgradeableReadLock();      try {        _lock.EnterReadLock();        try {          if (_lastTicks != lastTicks) {            if (_map.TryGetValue(key, out tuple)) {              if (_expireTicks == -1) return tuple.Item2;              if (tuple.Item1 + _expireTicks > DateTime.Now.Ticks) return tuple.Item2;            }            lastTicks = _lastTicks;          }        } finally { _lock.ExitReadLock(); }        _slimLock.EnterWriteLock();        try {          if (_lockDict.TryGetValue(key, out slim) == false) {            slim = new AntiDupLockSlim();            _lockDict[key] = slim;          }          slim.UseCount++;        } finally { _slimLock.ExitWriteLock(); }      } finally { _slimLock.ExitUpgradeableReadLock(); }      slim.EnterWriteLock();      try {        _lock.EnterReadLock();        try {          if (_lastTicks != lastTicks && _map.TryGetValue(key, out tuple)) {            if (_expireTicks == -1) return tuple.Item2;            if (tuple.Item1 + _expireTicks > DateTime.Now.Ticks) return tuple.Item2;          }        } finally { _lock.ExitReadLock(); }        var val = factory();        _lock.EnterWriteLock();        try {          _lastTicks = DateTime.Now.Ticks;          _map[key] = Tuple.Create(_lastTicks, val);          if (_maxCount > 0) {            if (_queue.Contains(key) == false) {              _queue.Enqueue(key);              if (_queue.Count > _maxCount) _map.Remove(_queue.Dequeue());            }          }        } finally { _lock.ExitWriteLock(); }        return val;      } finally {        slim.ExitWriteLock();        _slimLock.EnterWriteLock();        try {          slim.UseCount--;          if (slim.UseCount == 0) {            _lockDict.Remove(key);            slim.Dispose();          }        } finally { _slimLock.ExitWriteLock(); }      }    }    /// <summary>    /// 清空    /// </summary>    public void Clear()    {      _lock.EnterWriteLock();      try {        _map.Clear();        _queue.Clear();        _slimLock.EnterWriteLock();        try {          _lockDict.Clear();        } finally {          _slimLock.ExitWriteLock();        }      } finally {        _lock.ExitWriteLock();      }    }  }

private readonly static AntiDupCache<int, int> antiDupCache = new AntiDupCache<int, int>(50, 1);  antiDupCache.Execute(key, () => {     ....     return val;  });