自定义EventSource（二）PollingCounter

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

本例先说一下用PollingCounter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PollingCounterDemo。

WorkingEventSouce事件源

/// <summary>
/// Working业务事件源
/// </summary>
[EventSource(Name = "WorkingEventSource")]
public sealed class WorkingEventSource : EventSource
{
    public static readonly WorkingEventSource Instance = new WorkingEventSource();
    private PollingCounter _workingCounter;

    //间隔内总时间
    private double _elapsedMilliseconds = 0;
    //间隔内次数
    private int _times = 0;
    /// <summary>
    /// working-time 是dotnet-counters  --counters的参数
    /// </summary>
    private WorkingEventSource() =>
        _workingCounter = new PollingCounter("working-time", this, MetricProvider)
        {
            DisplayName = "Working Time",
            DisplayUnits = "ms"
        };
    /// <summary>
    /// 自定义函数，来计算指标，本例模拟EventCounter的计算方式
    /// </summary>
    /// <returns></returns>
    double MetricProvider()
    {
        var value = _elapsedMilliseconds / _times;
        _elapsedMilliseconds = 0;
        _times = 0;
        return value;
    }
    /// <summary>
    /// Working发送业务指标
    /// </summary>
    /// <param name="elapsedMilliseconds"></param>
    public void Working(long elapsedMilliseconds)
    {
        _times++;
        _elapsedMilliseconds += elapsedMilliseconds;
    }

    protected override void Dispose(bool disposing)
    {
        _workingCounter?.Dispose();
        _workingCounter = 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 WorkingEventListener : 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"))
        {
            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PollingCounterDemo

public class PollingCounterDemo
{
    public static void Run()
    {
        var listener = new WorkingEventListener();
        listener.WriteEvent += Listener_WriteEvent;
        new Thread(Working).Start();
    }
    //以控制台方式展示采集到的指标
    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;
        }
    }
}

运行结果如下，当然这个值是MetricProvider计算出来的，可以按自己收集指标的算法，算每次采集到的值并返回