TraceLevel Values in Visual C#.NET

Making PDF 417 in Visual C#.NET TraceLevel Values

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Each of the higher levels implies the lower level; for example, if the level is set to Info, Error and Warning will also be set. You use these numeric values when setting the flag via an environment variable or registry setting. The TraceSwitch class exposes properties that tell whether a specific trace level has been set, and a typical logging statement checks to see whether the appropriate property was set. Here s the previous example, modified to use different logging levels: // compile with: csc /r:system.dll file_1.cs using System; using System.Diagnostics; class MyClass { public MyClass(int i) { this.i = i; } [Conditional("DEBUG")] public void VerifyState() { Debug.WriteLineIf(debugOutput.TraceInfo, "VerifyState Start"); Debug.WriteLineIf(debugOutput.TraceVerbose, "Starting field verification"); if (debugOutput.TraceInfo) Debug.WriteLine("VerifyState End"); }

static TraceSwitch debugOutput = new TraceSwitch("MyClassDebugOutput", "Control debug output"); int i = 0; } class Test { public static void Main() { Debug.Listeners.Clear(); Debug.Listeners.Add(new TextWriterTraceListener(Console.Out)); MyClass c = new MyClass(1); c.VerifyState(); } }

The Switch class nicely encapsulates getting the switch value from the registry, so it s easy to derive a custom switch if the values of TraceSwitch don t work well. The following example implements SpecialSwitch, which implements the Mute, Terse, Verbose, and Chatty logging levels: // compile with: csc /r:system.dll file_1.cs using System; using System.Diagnostics; enum SpecialSwitchLevel { Mute = 0, Terse = 1, Verbose = 2, Chatty = 3 } class SpecialSwitch: Switch { public SpecialSwitch(string displayName, string description) : base(displayName, description) { }

public SpecialSwitchLevel Level { get { return((SpecialSwitchLevel) base.SwitchSetting); } set { base.SwitchSetting = (int) value; } } public bool Mute { get { return(base.SwitchSetting == 0); } } public bool Terse { get { return(base.SwitchSetting } } public bool Verbose { get { return(base.SwitchSetting } } public bool Chatty { get { return(base.SwitchSetting } }

>= (int) (SpecialSwitchLevel.Terse));

>= (int) SpecialSwitchLevel.Verbose);

>=(int) SpecialSwitchLevel.Chatty);

protected new int SwitchSetting { get { return((int) base.SwitchSetting); } set { if (value value if (value value < = > = 0) 0; 4) 4;

base.SwitchSetting = value; } } } class MyClass { public MyClass(int i) { this.i = i; } [Conditional("DEBUG")] public void VerifyState() { Console.WriteLine("VerifyState"); Debug.WriteLineIf(debugOutput.Terse, "VerifyState Start"); Debug.WriteLineIf(debugOutput.Chatty, "Starting field verification"); if (debugOutput.Verbose) Debug.WriteLine("VerifyState End"); } static SpecialSwitch debugOutput = new SpecialSwitch("MyClassDebugOutput", "application"); int i = 0; }

class Test { public static void Main() { Debug.Listeners.Clear(); Debug.Listeners.Add(new TextWriterTraceListener(Console.Out)); MyClass c = new MyClass(1); c.VerifyState(); } } You can control this switch with the same config file as the previous example.

Simply outputting a string that records what a particular thread is doing is insufficient to monitor operations and track down problems in production environments. It isn t usually necessary to have thousands of threads running within hundreds of processes on dozens of machines. Although it s interesting that a particular thread called Trace.WriteLine() exists and has recorded that an error occurred, finding the actual thread that originated the statement, along with other metadata about the state of the process, is also interesting. To allow you to capture this information without having to manually code its retrieval, the Trace class in the 2.0 release of the .NET Framework libraries includes a new method called TraceInformation(). This method is capable of outputting the thread s call stack, the date and time the Trace statement was made, the logical operation stack (which is the chain of calls in the current call context and may span multiple threads), the process ID, the thread ID, and the time stamp (which is a long that represents the number of ticks in the system timer and is a higher resolution than the date and time value that s also available). The actual listener decides which output values should be collected for a TraceInformation statement. To add and output all the available information, use the following code: ConsoleTraceListener ctl = new ConsoleTraceListener(); ctl.TraceOutputOptions = TraceOptions.Callstack | TraceOptions.DateTime | TraceOptions.LogicalOperationStack | TraceOptions.ProcessId | TraceOptions.ThreadId | TraceOptions.Timestamp; System.Diagnostics.Trace.Listeners.Add(ctl); Trace.TraceInformation("An error occurred "); Running this code produces the following output: