Gauges
可以画出Http Request执行时间的波形图：
actionInfo表示MVC中的Action，即按照action类型来分组
Metric.Context(this.actionInfo.ActionType)
.Gauge(counterName, () => milliseconds, Unit.Custom("Milliseconds"));
Counters
记录总的请求数和并发请求数：
public class WebApiApplication : System.Web.HttpApplication
{
private readonly Counter totalRequestsCounter =
Metric.Context("[Request]").Counter("Total_Requests", Unit.Custom("個"), "request");
private readonly Counter concurrentRequestsCounter =
Metric.Context("[Request]").Counter("Concurrent_Requests", Unit.Custom("個"), "request,concurrent");
/// <summary>
/// 應用程序啟動方法
/// </summary>
protected void Application_Start()
{
GlobalConfiguration.Configure(WebApiConfig.Register);
Metric.Config
.WithHttpEndpoint("http://localhost:1234/metrics/");
//Metric.Config.WithHttpEndpoint("http://+:8898/")//外网可以访问
}
/// <summary>
/// 開始請求
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void Application_BeginRequest(object sender, EventArgs e)
{
totalRequestsCounter.Increment();
concurrentRequestsCounter.Increment();
}
/// <summary>
/// 結束請求
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void Application_EndRequest(object sender, EventArgs e)
{
concurrentRequestsCounter.Decrement();
}
}
Histograms
度量POST&PUT请求大小的直方图：
public PostAndPutRequestSizeMetric(ActionInfo info)
: base(info)
{
this.histogram = Metric.Context(this.actionInfo.ActionType)
.Histogram(COUNTER_NAME, Unit.Bytes, SamplingType.FavourRecent);
}
/// <summary>
/// Constant defining the name of this counter
/// </summary>
public const String COUNTER_NAME = "Post & Put Request Size";
/// <summary>
/// Reference to the performance counter
/// </summary>
private Histogram histogram;
public override void OnActionStart()
{
var method = this.actionInfo.HttpMethod.ToUpper();
if (method == "POST" || method == "PUT")
{
histogram.Update(this.actionInfo.ContentLength);
}
}
Histrogram 的度量值不仅仅是计算最大/小值、平均值，方差，他还展现了分位数（如中位数，或者95th分位数），如75%,90%,98%,99%的数据在哪个范围内。
传统上，中位数（或者其他分位数）是在一个完整的数据集中进行计算的，通过对数据的排序，然后取出中间值（或者离结束1%的那个数字，来计算99th分位数）。这种做法是在小数据集，或者是批量计算的系统中，但是在一个高吞吐、低延时的系统中是不合适的。
一个解决方案就是从数据中进行抽样，保存一个少量、易管理的数据集，并且能够反应总体数据流的统计信息。使我们能够简单快速的计算给定分位数的近似值。这种技术称作reservoir sampling。
Meters
Meter度量一系列事件发生的比率：
public DeltaExceptionsThrownMetric(ActionInfo info)
: base(info)
{
this.deltaExceptionsThrownCounter
= Metric.Context(this.actionInfo.ActionType).Meter(COUNTER_NAME, Unit.Errors, TimeUnit.Seconds);
}
/// <summary>
/// Constant defining the name of this counter
/// </summary>
public const String COUNTER_NAME = "Errors";
/// <summary>
/// Reference to the performance counter
/// </summary>
private Meter deltaExceptionsThrownCounter;
/// <summary>
/// Method called by the custom action filter after the action completes
/// </summary>
/// <remarks>
/// If exceptionThrown is true, then the Total Exceptions Thrown counter will be
/// incremented by 1
/// </remarks>
public override void OnActionComplete(long elapsedTicks, bool exceptionThrown)
{
if (exceptionThrown)
this.deltaExceptionsThrownCounter.Mark();
}
Meter需要除了Name之外的两个额外的信息，事件类型（enent type）跟比率单位（rate unit）。事件类型简单的描述Meter需要度量的事件类型，在上面的例子中，Meter是度量失败的请求数，所以他的事件类型也叫做“Errors”。比率单位是命名这个比率的单位时间，在上面的例子中，这个Meter是度量每秒钟的失败请求次数，所以他的单位就是秒。这两个参数加起来就是表述这个Meter，描述每秒钟的失败请求数。
Timers
Timer是Histogram跟Meter的一个组合
public TimerForEachRequestMetric(ActionInfo info)
: base(info)
{
String controllerName = this.actionInfo.ControllerName;
String actionName = this.actionInfo.ActionName;
string counterName = string.Format("{0}{1}", controllerName, actionName);
this.averageTimeCounter = Metric.Context(this.actionInfo.ActionType)
.Timer(counterName, Unit.Requests, SamplingType.FavourRecent,
TimeUnit.Seconds, TimeUnit.Milliseconds);
}
#region Member Variables
private Timer averageTimeCounter;
#endregion
/// <summary>
/// Method called by the custom action filter after the action completes
/// </summary>
/// <remarks>
/// This method increments the Average Time per Call counter by the number of ticks
/// the action took to complete and the base counter is incremented by 1 (this is
/// done in the PerfCounterUtil.IncrementTimer() method).
/// </remarks>
/// <param name="elapsedTicks">A long of the number of ticks it took to complete the action</param>
public override void OnActionComplete(long elapsedTicks, bool exceptionThrown)
{
averageTimeCounter.Record(elapsedTicks, TimeUnit.Nanoseconds);
}