javatools.administrative

Class Tracer

java.lang.Object

javatools.administrative.Tracer

public class Tracer
extends Object

Copyright 2016 Fabian M. Suchanek Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. This class allows to trace where a program hangs. Use as follows:

  Before calling a method in your program, call Tracer.signal():
      Tracer.signal("Calling blah");
  In your main method, state
      Tracer.start(number of milliseconds);

  Whenever the tracer does not receive a signal for the given number of milliseconds,
  it writes a warning, such as e.g.
     Calling blah hangs
  When it receives the next signal, it will say
     Hang resolved

Use the tracer for debugging purposes only.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	Tracer.TracerThread The thread itself

Field Summary

Fields

Modifier and Type	Field and Description
protected static Tracer.TracerThread	tracer Internal trace thread

Constructor Summary

Constructors

Constructor and Description
Tracer()

Method Summary

Modifier and Type	Method and Description
static void	main(String[] args) Calls test1 and test2 in a loop.
static boolean	signal(Object... s) Send a signal to the tracer.
static boolean	start(long millisDelay) Start the tracer, accept millisDelay milliseconds between two signals before issuing a warning.
static void	stop() Stop the tracer
static void	test1() Sleeps for 2 seconds.
static void	test2() Sleeps for 5 seconds.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

tracer

protected static Tracer.TracerThread tracer

Internal trace thread

Constructor Detail

Tracer

public Tracer()

Method Detail

start

public static boolean start(long millisDelay)

Start the tracer, accept millisDelay milliseconds between two signals before issuing a warning. Returns TRUE so that it can be used in an assert statement

stop

public static void stop()

Stop the tracer

signal

public static boolean signal(Object... s)

Send a signal to the tracer. Always returns TRUE so that it can be used in assert

test1

public static void test1()

Sleeps for 2 seconds. Tracer will not say anything

test2

public static void test2()

Sleeps for 5 seconds. Tracer will write a warning

main

public static void main(String[] args)

Calls test1 and test2 in a loop. Tracer will complain whenever some call takes longer than 3 seconds