[SOLVED] Using perf4J Profiled annotation without other libraries (like log4j for example)

Using perf4J Profiled annotation without other libraries (like log4j for example)

When using perf4J, this code works well:

StopWatch stopWatch = new LoggingStopWatch();
stopWatch.stop("example1", "custom message text");

But when using @Profiled, what to do to output or get measures, with minimum of code:

@Profiled(tag = "dynamicTag_{$0}")
public void boucle(int k)
{
    // My code to profile
}

Solution

When using the @Profiled annotation to add stopwatches to your code, you will typically use AspectJ Load Time Weaving (LTW) to instrument your code at load/runtime, which adds the stopwatch starts/stops and recordings around annotated methods.

Which logging library/API (log4j, slf4j, commons-logging, JUL) is used depends on the specific instance of org.perf4j.aop.ProfiledTimingAspect you configure in your aop.xml configuring your LTW. For example this config:

<aspectj>
  <!--
    We only want to weave in the log4j TimingAspect into the @Profiled classes.
    Note that Perf4J provides TimingAspects for the most popular Java logging
    frameworks and facades: log4j, java.util.logging, Apache Commons Logging
    and SLF4J. The TimingAspect you specify here will depend on which logging
    framework you wish to use in your code.
  -->
  <aspects>
    <aspect name="org.perf4j.log4j.aop.TimingAspect"/>
    <!-- if SLF4J/logback use org.perf4j.slf4j.aop.TimingAspect instead -->
  </aspects>

  <weaver options="-verbose -showWeaveInfo">
    <!--
      Here is where we specify the classes to be woven. You can specify package
      names like com.company.project.*
    -->
    <include within="ProfiledExample"/>
  </weaver>
</aspectj>

... uses org.perf4j.log4j.aop.TimingAspect, so the stopwatches will be logged to your configured Log4J stopwatch logger. If you want to avoid third-party libraries, you can change this for the JUL JDK logger.