通話每一天率ASP.NET MVC 3限制？

Question

我見過賈羅德·狄克遜的實現來電每秒的速率限制溶液（Best way to implement request throttling in ASP.NET MVC?）。我現在試圖弄清楚如何爲每日N次呼叫建立一個類似的過濾器。

我建立一個開發者的API，其中免費賬戶每天能獲得100〜電話和付費賬戶獲得更高的速率限制。在MVC 3中進行每日呼叫速率限制的最佳方式是什麼？

Answer 1

我不認爲在內存中的結構就足夠了這裏，因爲你需要測量時間長。在這種情況下，IIS回收會有問題。因此，我建議記錄用戶對數據庫資源的訪問權限，並且只允許在過去24小時內計數100。

在另一方面，這裏是我們實現一個漏桶限幅（這是短期的限制，其中失敗是相對不重要更加得心應手）的。使用.NET 4併發集合可能會改善這種實現中的某種暴力鎖定：

public class RateLimiter 
{ 
    private readonly double numItems; 
    private readonly double ratePerSecond; 
    private readonly Dictionary<object, RateInfo> rateTable = 
     new Dictionary<object, RateInfo>(); 
    private readonly object rateTableLock = new object(); 
    private readonly double timePeriod; 

    public RateLimiter(double numItems, double timePeriod) 
    { 
     this.timePeriod = timePeriod; 
     this.numItems = numItems; 
     ratePerSecond = numItems/timePeriod; 
    } 

    public double Count 
    { 
     get 
     { 
      return numItems; 
     } 
    } 

    public double Per 
    { 
     get 
     { 
      return timePeriod; 
     } 
    } 

    public bool IsPermitted(object key) 
    { 
     RateInfo rateInfo; 
     var permitted = true; 
     var now = DateTime.UtcNow; 
     lock (rateTableLock) 
     { 
      var expiredKeys = 
       rateTable 
       .Where(kvp => 
        (now - kvp.Value.LastCheckTime) 
        > TimeSpan.FromSeconds(timePeriod)) 
       .Select(k => k.Key) 
       .ToArray(); 
      foreach (var expiredKey in expiredKeys) 
      { 
       rateTable.Remove(expiredKey); 
      } 
      var dataExists = rateTable.TryGetValue(key, 
                out rateInfo); 
      if (dataExists) 
      { 
       var timePassedSeconds = (now - rateInfo.LastCheckTime).TotalSeconds; 
       var newAllowance = 
        Math.Min(
         rateInfo.Allowance 
         + timePassedSeconds 
         * ratePerSecond, 
         numItems); 
       if (newAllowance < 1d) 
       { 
        permitted = false; 
       } 
       else 
       { 
        newAllowance -= 1d; 
       } 
       rateTable[key] = new RateInfo(now, 
               newAllowance); 
      } 
      else 
      { 
       rateTable.Add(key, 
           new RateInfo(now, 
              numItems - 1d)); 
      } 

     } 
     return permitted; 
    } 

    public void Reset(object key) 
    { 
     lock (rateTableLock) 
     { 
      rateTable.Remove(key); 
     } 
    } 

    private struct RateInfo 
    { 
     private readonly double allowance; 
     private readonly DateTime lastCheckTime; 

     public RateInfo(DateTime lastCheckTime, double allowance) 
     { 
      this.lastCheckTime = lastCheckTime; 
      this.allowance = allowance; 
     } 

     public DateTime LastCheckTime 
     { 
      get 
      { 
       return lastCheckTime; 
      } 
     } 

     public double Allowance 
     { 
      get 
      { 
       return allowance; 
      } 
     } 
    } 

}