act.metric

Interface Metric

All Known Implementing Classes:

SimpleMetric

public interface Metric

Metric is used to measure the application and framework performance.

Two kinds of metrics are been implemented in ActFramework:

• Counter - count number of time an event occurred
• Timer - measure the time spent on a specific event

ActFramework supports hierarchical metric. For example, suppose you want to measure the time spent on direct web request handling and background jobs:

measure direct request handling

     @PostAction("/xyz")
    public void handleXyzRequest(String param) {
        Timer timer = metric.startTimer("direct_req_handling:xyz");
        try {
            // your logic to handle xyz request
        } finally {
            timer.stop();
        }
    }

measure a background job

     @Every("1hr")
    public void scanDatabase() {
        Timer timer = metric.startTimer("background_job:scan_db");
        try {
            // your logic to scan database
        } finally {
            timer.stop();
        }
    }

In the sample code shown above, the name used to start timers are direct_req_handling:xyz and background_job:scan_db respectively. Both name contains a metric hierarchy, say direct_req_handling followed by xyz and background_job followed by scan_db. The benefit of metric hierarchy is the value measured on child name will get aggregated automatically on parent name: Suppose you have two counters: “a:b”: 100, and “a:c”: 105, then your “a” counter will be 205.

Field Summary

Fields

Modifier and Type	Field and Description
static Metric	NULL_METRIC The do-nothing metric instance
static String	PATH_SEPARATOR PATH_SEPARATOR is provided to support hierarchical metric

Method Summary

Modifier and Type	Method and Description
void	countOnce(String name) Call this method to increase one time for the counter specified
Timer	startTimer(String name) Call this method to start a Timer before starting a process.

Field Detail

PATH_SEPARATOR

static final String PATH_SEPARATOR

PATH_SEPARATOR is provided to support hierarchical metric

See Also:

Constant Field Values

NULL_METRIC

static final Metric NULL_METRIC

The do-nothing metric instance

Method Detail

countOnce

void countOnce(String name)

Call this method to increase one time for the counter specified

Parameters:

name - A string specifies the counter

startTimer

Timer startTimer(String name)

Call this method to start a Timer before starting a process.

Note calling this method should automatically call countOnce(String) method with the name specified

Parameters:

name - A string specifies the timer

Returns:

a Timer instance