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// to you 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

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package org.apache.impala.common;

import java.text.DecimalFormat;

import java.util.Map.Entry;

import com.codahale.metrics.Counter;

import com.codahale.metrics.Gauge;

import com.codahale.metrics.Histogram;

import com.codahale.metrics.Meter;

import com.codahale.metrics.MetricRegistry;

import com.codahale.metrics.Snapshot;

import com.codahale.metrics.Timer;

/**

* Thin wrapper class around MetricRegisty. Allows users to register and access metrics of

* various types (counter, meter, histogram, and timer). This class is not thread-safe.

* TODO: Expose the metrics in Json format via a toJson() function.

*/

public final class Metrics {

// formatter to round the double values of the rate counters to 4 digits after decimal

private static final DecimalFormat decimalFormatter_ = new DecimalFormat("#.####");

private final MetricRegistry registry_ = new MetricRegistry();

public Metrics() {}

public void addCounter(String name) { registry_.counter(name); }

public void addMeter(String name) { registry_.meter(name); }

public void addHistogram(String name) { registry_.histogram(name); }

public void addTimer(String name) { registry_.timer(name); }

@SuppressWarnings("rawtypes")

public <T extends Gauge> void addGauge(String name, T gauge) {

registry_.register(name, gauge);

}

/**

* Returns a counter named 'name'. If the counter does not exist, it is registered in

* the metrics registry.

*/

public Counter getCounter(String name) {

Counter counter = registry_.getCounters().get(name);

if (counter == null) counter = registry_.counter(name);

return counter;

}

/**

* Returns a meter named 'name'. If the meter does not exist, it is registered in the

* metrics registry.

*/

public Meter getMeter(String name) {

Meter meter = registry_.getMeters().get(name);

if (meter == null) meter = registry_.meter(name);

return meter;

}

/**

* Returns a histogram named 'name'. If the histogram does not exist, it is registered

* in the metrics registry.

*/

public Histogram getHistogram(String name) {

Histogram histogram = registry_.getHistograms().get(name);

if (histogram == null) histogram = registry_.histogram(name);

return histogram;

}

/**

* Returns a timer named 'name'. If the timer does not exist, it is registered in the

* metrics registry.

*/

public Timer getTimer(String name) {

Timer timer = registry_.getTimers().get(name);

if (timer == null) timer = registry_.timer(name);

return timer;

}

@SuppressWarnings("rawtypes")

public Gauge getGauge(String name) { return registry_.getGauges().get(name); }

/**

* Returns a string representation of all registered metrics.

*/

@Override

@SuppressWarnings("rawtypes")

public String toString() {

StringBuilder result = new StringBuilder();

for (Entry<String, Counter> entry: registry_.getCounters().entrySet()) {

result.append(entry.getKey() + ": " + String.valueOf(entry.getValue().getCount()));

result.append("\n");

}

for (Entry<String, Timer> entry: registry_.getTimers().entrySet()) {

result.append(entry.getKey() + ": " + timerToString(entry.getValue()));

result.append("\n");

}

for (Entry<String, Gauge> entry: registry_.getGauges().entrySet()) {

result.append(entry.getKey() + ": " + String.valueOf(entry.getValue().getValue()));

result.append("\n");

}

for (Entry<String, Histogram> entry: registry_.getHistograms().entrySet()) {

result.append(entry.getKey() + ": " +

snapshotToString(entry.getValue().getSnapshot()));

result.append("\n");

}

for (Entry<String, Meter> entry : registry_.getMeters().entrySet()) {

result.append(entry.getKey()).append(":").append(meterToString(entry.getValue()));

result.append("\n");

}

return result.toString();

}

/**

* Helper function that pretty prints the contents of a timer metric.

*/

private String timerToString(Timer timer) {

StringBuilder builder = new StringBuilder();

return builder.append("\n Count: " + timer.getCount())

.append("\n Mean rate: ")

.append(decimalFormatter_.format(timer.getMeanRate()))

.append("\n 1 min. rate: ")

.append(decimalFormatter_.format(timer.getOneMinuteRate()))

.append("\n 5 min. rate: ")

.append(decimalFormatter_.format(timer.getFiveMinuteRate()))

.append("\n 15 min. rate: ")

.append(decimalFormatter_.format(timer.getFifteenMinuteRate()))

.append(snapshotToString(timer.getSnapshot()))

.toString();

}

/**

* Helper method to pretty print the contents of a Meter

*/

private String meterToString(Meter meter) {

StringBuilder builder = new StringBuilder();

return builder.append("\n Count: ")

.append(meter.getCount())

.append("\n Mean rate: ")

.append(decimalFormatter_.format(meter.getMeanRate()))

.append("\n 1 min. rate: ")

.append(decimalFormatter_.format(meter.getOneMinuteRate()))

.append("\n 5 min. rate: ")

.append(decimalFormatter_.format(meter.getFiveMinuteRate()))

.append("\n 15 min. rate: ")

.append(decimalFormatter_.format(meter.getFifteenMinuteRate()))

.toString();

}

/**

* Helper function that pretty prints the contents of a metric snapshot.

*/

private String snapshotToString(Snapshot snapshot) {

StringBuilder builder = new StringBuilder();

return builder.append("\n Min (msec): ")

.append(decimalFormatter_.format(snapshot.getMin() / 1000000))

.append("\n Max (msec): ")

.append(decimalFormatter_.format(snapshot.getMax() / 1000000))

.append("\n Mean (msec): ")

.append(decimalFormatter_.format(snapshot.getMean() / 1000000))

.append("\n Median (msec): ")

.append(decimalFormatter_.format(snapshot.getMedian() / 1000000))

.append("\n 75th-% (msec): ")

.append(decimalFormatter_.format(snapshot.get75thPercentile() / 1000000))

.append("\n 95th-% (msec): ")

.append(decimalFormatter_.format(snapshot.get95thPercentile() / 1000000))

.append("\n 99th-% (msec): ")

.append(decimalFormatter_.format(snapshot.get99thPercentile() / 1000000))

.append("\n")

.toString();

}

}