自定义EventSource（三）IncrementingEventCounter

在自定义EventSource时，可以使用四种EventCounter：

• EventCounter：统计指标收集器，比如平均值，最大值，最小值
• PollingCounter：自定义统计指标收集器，通过自定义统计方法的方式实现对指标的统计
• IncrementingEventCounter：累加指标收集器，采集一定时间段内的指标汇总
• IncrementingPollingCounter：自定义累加指标收集器，通过自定义累函数，实现指标收集

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本例先说一下用IncrementingEventCounter实现自定义EventSource。

本例是定义了一个WorkingEventSouce事件源，定义了WorkingEventListener监听器，和发送指标采集指标的类型IncrementingEventCounterDemo。

WorkingEventSouce事件源

[EventSource(Name = "WorkingEventSource")]
public sealed class WorkingEventSource : EventSource
{
    public static readonly WorkingEventSource Instance = new WorkingEventSource();
    private IncrementingEventCounter _requestCounter;
    /// <summary>
    /// working-time 是dotnet-counters  --counters的参数
    /// </summary>
    private WorkingEventSource() =>
        _requestCounter = new IncrementingEventCounter("working-time", this)
        {
            DisplayName = "Request Processing Time",
            DisplayUnits = "ms"
        };
    /// <summary>
    /// Working发送业务指标
    /// </summary>
    /// <param name="elapsedMilliseconds"></param>
    public void Working(long elapsedMilliseconds)
    {
        _requestCounter.Increment(elapsedMilliseconds);
    }

    protected override void Dispose(bool disposing)
    {
        _requestCounter?.Dispose();
        _requestCounter = null;
        base.Dispose(disposing);
    }
}

WorkingEventListener监听器

/// <summary>
/// 指标输出委托
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
public delegate void WriteContent(string key, string value);
/// <summary>
/// 指标监听器
/// </summary>
public class CustomEventListener : EventListener
{
    protected readonly string[] _countersName = new string[] { "WorkingEventSource" };

    public event WriteContent WriteEvent;
    protected override void OnEventSourceCreated(EventSource source)
    {
        if (_countersName.Contains(source.Name))
        {
            EnableEvents(source, EventLevel.Verbose, EventKeywords.All, new Dictionary<string, string>()
            {
                ["EventCounterIntervalSec"] = "1"
            });
        }
    }

    protected override void OnEventWritten(EventWrittenEventArgs eventData)
    {
        if (!eventData.EventName.Equals("EventCounters"))
        {
            return;
        }
        for (int i = 0; i < eventData.Payload.Count; ++i)
        {
            if (eventData.Payload[i] is IDictionary<string, object> eventPayload)
            {
                var counterName = "";
                var counterValue = "";
                if (eventPayload.TryGetValue("DisplayName", out object displayValue))
                {
                    counterName = displayValue.ToString();
                }
                if (eventPayload.TryGetValue("Mean", out object value) ||
                    eventPayload.TryGetValue("Increment", out value))
                {
                    counterValue = value.ToString();
                }
                WriteEvent(counterName, counterValue);
            }
        }
    }
}

发送指标采集指标的类型IncrementingEventCounterDemo

 public class IncrementingEventCounterDemo
 {
     public static void Run()
     {
         var listener = new CustomEventListener();
         listener.WriteEvent += Listener_WriteEvent;
         new Thread(Working).Start();
     }
     /// <summary>
     ///  以控制台方式展示采集到的指标
     /// </summary>
     /// <param name="key"></param>
     /// <param name="value"></param>
     private static void Listener_WriteEvent(string key, string value)
     {
         Console.WriteLine($"{key}：{value}");
     }
     /// <summary>
     /// 模拟写业务指标，每秒写两次，i递增
     /// </summary>
     static void Working()
     {
         int i = 0;
         while (true)
         {
             var count = i;
             Console.WriteLine(count);
             WorkingEventSource.Instance.Working(count);
             System.Threading.Thread.Sleep(500);
             i += 1;
         }
     }
}

结果，可以看到，每次都是时间段里数值之和

下图是跟踪EventListener的OnEventWritten的Payload有效载荷时的数据，可以看到有时间段内总和—Increment，次数，时间间隔等信息，这是因为当前计数据类型是IncrementingEventCounter。