Package com.gargoylesoftware.base.trace

Class Trace

java.lang.Object
com.gargoylesoftware.base.trace.Trace
public class Trace extends Object
A class that provides a mechanism for logging diagnostic messages. This mechanism is significantly faster then calling System.out.println directly as the printing is done on a background thread which does not impact the performance of the application threads.

The methods for tracing are print(String), println(String) and printStackTrace(Throwable). The basic idea is that we want the trace methods to return to the working threads as quickly as possible so we put the thing to be traced on a queue. The queue is then processed by a second thread which performs all the formatting and actual output.

Trace can be configured using the TraceController class - see getController(). It is possible to redirect System.out and System.err so that calling System.out.println("foo") will be the same as calling Trace.println("foo") 

 Trace.getController().setOutRedirected(true);
 Trace.getController().setErrRedirected(true);
Calls to any of the print methods will print to a TraceChannel which in turn will print using whatever TraceWriters have been added to it. Print methods that do not take a TraceChannel will use the default channel - see TraceController.setDefaultChannel(TraceChannel)

If you are using this code in a JVM prior to 1.3 then you need to read this:
Because trace lines are being processed on a second thread, there might still be trace messages in the queue when the VM exits. To solve this problem we introduce the method exit(int) which will shut down the second thread and then call System.exit(). If you are running on a java 1.3 VM or higher then it is not neccessary to call exit(int) as Trace will automatically install a shutdown hook which will do the neccessary cleanup.

Version:
$Revision: 1.6 $

  • Field Details

    • out

      public static final TraceChannel out
      The equivilent of "standard out"

    • err

      public static final TraceChannel err
      The equivilent of "standard error"

    • LINE_SEPARATOR

      private static final String LINE_SEPARATOR

    • TRACE_ITEM_DISPATCHER

      private static final TraceItemDispatcher TRACE_ITEM_DISPATCHER

    • TRACE_CONTROLLER

      private static final TraceController TRACE_CONTROLLER

  • Constructor Details

    • Trace

      private Trace()
      Private constructor to prevent instantiation of this class.

  • Method Details

    • print

      public static void print(TraceChannel channel, String string)
      Print a line to the specified channel. If the channel is null then nothing will be printed.
      Parameters:
      channel - The trace channel to use
      string - The text string to write.

    • print

      public static void print(String string)
      Print a line to the default channel If the channel is null then nothing will be printed.
      Parameters:
      string - The text string to write.

    • println

      public static void println(TraceChannel channel, String string)
      Print the line to the specified channel with a new line at the end. If the channel is null then nothing will be printed.
      Parameters:
      channel - The trace channel to use
      string - the string to write.

    • println

      public static void println(String string)
      Print the line to the default channel with a new line at the end.
      Parameters:
      string - the string to write.

    • printStackTrace

      public static void printStackTrace(TraceChannel channel, Throwable throwable)
      Print the stack trace to the specified channel. If the channel is null then nothing will be printed.
      Parameters:
      channel - The trace channel to use
      throwable - The exception to print

    • printStackTrace

      public static void printStackTrace(Throwable throwable)
      Print the stack trace to the default channel.
      Parameters:
      throwable - The exception to print.

    • printLines

      public static void printLines(String[] lines)
      Print the specified lines to the default trace channel.
      Parameters:
      lines - The lines to print.

    • printLines

      public static void printLines(TraceChannel channel, String[] lines)
      Print the specified lines to the trace channel. If the channel is null then nothing will be printed.
      Parameters:
      channel - The trace channel to use
      lines - the lines to print.

    • whereAmI

      public static void whereAmI()
      Print a stack trace to show where we came from. It will be printed to the default channel.

    • whereAmI

      public static void whereAmI(TraceChannel channel)
      Print a stack trace to show where we came from. If the channel is null then nothing will be printed.
      Parameters:
      channel - The trace channel to use.

    • throwableToStringArray

      public static String[] throwableToStringArray(Throwable t)
      Dump the stack trace from the specified throwable into an array of strings where each line in the trace is a separate string. Additionally, expand all tabs to spaces.
      Parameters:
      t - The exception.
      Returns:
      The resulting string.

    • throwableToString

      public static String throwableToString(Throwable t)
      Dump the stack trace from the specified throwable into a String.
      Parameters:
      t - The exception.
      Returns:
      The resulting string.

    • getController

      public static TraceController getController()
      Return the controller object for the debugging stuff
      Returns:
      The controller in use.

    • getDispatcher

      static TraceItemDispatcher getDispatcher()
      Returns:
      The dispatcher

    • flush

      public static void flush()
      Flush the trace queue.

    • exit

      public static void exit(int statusCode)
      Shutdown all buffering and exit the VM with the specified status code.

      Note This is no longer needed if you are running JDK1.3 or higher as we now register a shutdown hook to disable buffering before the VM exits.

      Parameters:
      statusCode - The status code returned when the application exits.

    • assertNotNull

      protected static final void assertNotNull(String fieldName, Object fieldValue) throws DetailedNullPointerException
      Verify that the specified value is not null. If it is then throw an exception
      Parameters:
      fieldName - The name of the field to check
      fieldValue - The value of the field to check
      Throws:
      DetailedNullPointerException - If fieldValue is null