Adding cache measurement metric points

The following code is a sample for how to gather a metric for use in cache measurement.

/**
* Perform an operation and capture the metrics required for cache potential
* analysis.
* 
* This implementation uses a standard Java Logger.
*/

private static final Level MEASURE_RESULT_SIZE_LEVEL = Level.FINER;
private static final Logger LOGGER = Logger.getLogger(SamplePerformanceLoggingFilter.class.getName());
private static final LogMetricGatherer LOG_GATHERER = new LogMetricGatherer(LOGGER);

@SuppressWarnings("null")
public void performOperationUsingLogger() {
  OperationMetric metric = null;
  
  // only log cache metrics if we log them to minimize overhead
  // if the metrics aren't actively used.
  boolean logOperationMetric = LOG_GATHERER.isLoggable();
  if (logOperationMetric) {
    metric = new OperationMetric();
    String operationName = "performOperation";
    boolean isOperationCacheEnabled = true;
    
    // all the parameters name-value pairs, converted to a string
    // format.
    String[] keyValuePairs = new String[] { "parameter1", "value1",
    "parameter2", "value2" };
    metric.startOperation(operationName, isOperationCacheEnabled,
    keyValuePairs);
  }
  
  // run the operation
  
  if (logOperationMetric) {
    // use the logger level to determine if we should perform
    // an expensive size measurement.
    boolean logSize = LOG_GATHERER.getLogger().isLoggable(
    MEASURE_RESULT_SIZE_LEVEL);
    int resultSize = 1;
    if (logSize) {
      // perform a more expensive result size measurement
    }
    boolean isResultFetchedFromCache = false;
    metric.stopOperation(resultSize, isResultFetchedFromCache);
    
    LOG_GATHERER.gatherMetric(metric);
  }
}

• The request unique ID and parent unique ID are automatically calculated with the startOperation and stopOperation method by using a thread-local variable. This automatic calculation means that operation IDs must be propagated through threads if an operation ever creates multiple threads.
• The request start time, end time, and duration are automatically calculated with the startOperation and stopOperation method by using nanosecond precision as provided by the JVM.
• The logger infrastructure is used to determine whether you should measure a request or not, to minimize the impact on the system when measurements are not required. The recommendation is to use the following three levels
  • Level.INFO and above - no measurement is performed.
  • Level.FINE - request metrics are measured, but not the response size.
  • Level.FINER - request metrics are measured, including the response size.
• The reason multiple level of loggers are used is to allow the measurement of metrics to occur in a production system and minimize the resource usage of the measurement process.