mcs/class/referencesource/System.Data/System/Data/Common/ActivityCorrelator.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="ActivityCorrelator.cs" company="Microsoft">
   3 //      Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">[....]</owner>
   6 //------------------------------------------------------------------------------
   7
   8 namespace System.Data.Common
   9 {
  10     using System;
  11     using System.Data;
  12     using System.Threading;
  13     using System.Diagnostics;
  14     using System.Globalization;
  15
  16     /// <summary>
  17     /// This class defines the data strucutre for ActvitiyId used for correlated tracing between client (bid trace event) and server (XEvent).
  18     /// It also includes all the APIs used to access the ActivityId. Note: ActivityId is thread based which is stored in TLS.
  19     /// </summary>
  20
  21     internal static class ActivityCorrelator
  22     {
  23         internal const Bid.ApiGroup CorrelationTracePoints = Bid.ApiGroup.Correlation;
  24
  25         internal class ActivityId
  26         {
  27             internal Guid Id { get; private set; }
  28             internal UInt32 Sequence { get; private set; }
  29
  30             internal ActivityId()
  31             {
  32                 this.Id = Guid.NewGuid();
  33                 this.Sequence = 0; // the first event will start 1
  34             }
  35
  36             // copy-constructor
  37             internal ActivityId(ActivityId activity)
  38             {
  39                 this.Id = activity.Id;
  40                 this.Sequence = activity.Sequence;
  41             }
  42
  43             internal void Increment()
  44             {
  45                 unchecked
  46                 {
  47                     ++this.Sequence;
  48                 }
  49             }
  50
  51             public override string ToString()
  52             {
  53                 return string.Format(CultureInfo.InvariantCulture, "{0}:{1}", this.Id, this.Sequence);
  54             }
  55         }
  56
  57         // Declare the ActivityId which will be stored in TLS. The Id is unique for each thread.
  58         // The Sequence number will be incremented when each event happens.
  59         // Correlation along threads is consistent with the current XEvent mechanisam at server.
  60         [ThreadStaticAttribute]
  61         static ActivityId tlsActivity;
  62
  63         /// <summary>
  64         /// Get the current ActivityId
  65         /// </summary>
  66         internal static ActivityId Current
  67         {
  68             get
  69             {
  70                 if (tlsActivity == null)
  71                 {
  72                     tlsActivity = new ActivityId();
  73                 }
  74
  75                 return new ActivityId(tlsActivity);
  76             }
  77         }
  78
  79         /// <summary>
  80         /// Increment the sequence number and generate the new ActviityId
  81         /// </summary>
  82         /// <returns>ActivityId</returns>
  83         internal static ActivityId Next()
  84         {
  85             if (tlsActivity == null)
  86             {
  87                 tlsActivity = new ActivityId();
  88             }
  89
  90             tlsActivity.Increment();
  91
  92             return new ActivityId(tlsActivity);
  93         }
  94     }
  95 }