wcf利用IDispatchMessageInspector实现接口监控日志记录和并发限流

 1 // 自定义分发消息检查器
 2     public class ThrottleDispatchMessageInspector : IDispatchMessageInspector
 3     {
 4         //TODO 这两个参数根据系统的配置处理方式存储，作为示例就直接写了 
 5         public static int throttleNum = 10; // 限流个数
 6         public static int throttleUnit = 4; // s
 7 
 8         CacheItemPolicy policy = new CacheItemPolicy();  //！ 过期策略，保证第一个set和之后set的绝对过期时间保持一致
 9 
10         #region implement IDispatchMessageInspector
11 
12         // 此方法的返回值 将作为方法BeforeSendReply的第二个参数 object correlationState传入
13         public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
14         {
15 
16 
17             // 获取ContractName和OperationName 用来作为缓存键
18             var context = OperationContext.Current;
19             string contractName = context.EndpointDispatcher.ContractName;
20             string operationName = string.Empty;
21             if (context.IncomingMessageHeaders.Action == null)
22             {
23                 operationName = request.Properties.Values.LastOrDefault().ToString();
24             }
25             else
26             {
27                 if (context.IncomingMessageHeaders.Action.Contains("/"))
28                 {
29                     operationName = context.IncomingMessageHeaders.Action.Split(‘/‘).LastOrDefault();
30                 }
31             }
32             string throttleCacheKey = contractName + "_" + operationName;
33             // 缓存当前请求频率， 以内存缓存System.Runtime.Caching.MemoryCache为例(.net4.0+)
34             ObjectCache cache = MemoryCache.Default;
35             var requestCount = cache.Get(throttleCacheKey);
36             int currRequestCount = 1;
37             if (requestCount != null && int.TryParse(requestCount.ToString(), out currRequestCount))
38             {
39                 // 访问次数+1
40                 currRequestCount++;
41                 cache.Set(throttleCacheKey, currRequestCount, policy);  //必须保证过期策略和第一次set的时候一致，不然过期时间会有问题
42             }
43             else
44             {
45                 policy.AbsoluteExpiration = DateTime.Now.AddSeconds(throttleUnit);
46                 cache.Set(throttleCacheKey, currRequestCount, policy);
47             }
48 
49             // 如果当前请求数大于阀值，直接关闭
50             if (currRequestCount > throttleNum)
51             {
52                 request.Close();
53             }
54 
55             //作为返回值 传给BeforeSendReply 
56             LogVO log = new LogVO
57             {
58                 BeginTime = DateTime.Now,
59                 ContractName = contractName,
60                 OperationName = operationName,
61                 Request = this.MessageToString(ref request),
62                 Response = string.Empty
63             };
64             return log;
65         }
66 
67         public void BeforeSendReply(ref Message reply, object correlationState)
68         {
69 
70             // 补充AfterReceiveRequest 传递过来的日志实体的属性, 记录
71             LogVO log = correlationState as LogVO;
72             log.EndTime = DateTime.Now;
73             log.Response = this.MessageToString(ref reply);
74             log.Duration = (log.EndTime - log.BeginTime).TotalMilliseconds;
75 
76             //attention 为不影响接口性能，日志实体push进队列（redis .etc），然后慢慢落地
77             //TODO 这里直接写文本啦~
78             try
79             {
80                 string logPath = "D:\\WcfLog.txt";
81                 if (!File.Exists(logPath))
82                 {
83                     File.Create(logPath);
84                 }
85                 StreamWriter writer = new StreamWriter(logPath, true);
86                 writer.Write(string.Format("at {0} , {1} is called , duration: {2} \r\n", log.BeginTime, log.ContractName + "." + log.OperationName, log.Duration));
87                 writer.Close();
88             }
89             catch (Exception ex) { }
90         }
91         #endregion
92 }