org.avaje.metric

Interface Metric

All Known Subinterfaces:

BucketTimedMetric, CounterMetric, GaugeDoubleGroup, GaugeDoubleMetric, GaugeLongGroup, GaugeLongMetric, TimedMetric, ValueMetric

public interface Metric

A Metric that collects statistics on events.

• TimedMetric and BucketTimedMetric are used for monitoring execution time
• CounterMetric is for counting discrete events like 'user logged in'
• ValueMetric is used when events have a value like bytes sent, lines read
• Gauges measure the current value of a resource like 'used memory' or 'active threads'.

Method Summary

Methods

Modifier and Type	Method and Description
void	clearStatistics() Clear the statistics resetting any internal counters etc.
boolean	collectStatistics() Typically this is only called by the MetricManager and tells the metric to collect its underlying statistics for reporting purposes and in addition resetting and internal counters it has.
MetricName	getName() Return the name of the metric.
void	visit(MetricVisitor visitor) Visit the metric typically reading and reporting the underlying statistics.

Method Detail

getName

MetricName getName()

Return the name of the metric.

collectStatistics

boolean collectStatistics()

Typically this is only called by the MetricManager and tells the metric to collect its underlying statistics for reporting purposes and in addition resetting and internal counters it has.

Returns:

true if this metric has some values. Returning false means that no events occurred since the last collection and typically a reporter omits this metric from the output that is sent.

visit

void visit(MetricVisitor visitor)
           throws IOException

Visit the metric typically reading and reporting the underlying statistics.

Typically this is use by reporters to traverse all the collected metrics for sending to a file or repository.

Throws:

IOException

clearStatistics

void clearStatistics()

Clear the statistics resetting any internal counters etc.

Typically the MetricManager takes care of resetting the statistic/counters for the metrics when it periodically collects and reports all the metrics and you are not expected to use this method.