package io.dropwizard.metrics;
import io.dropwizard.metrics.Counter;
import io.dropwizard.metrics.ExponentiallyDecayingReservoir;
import io.dropwizard.metrics.Gauge;
import io.dropwizard.metrics.Histogram;
import io.dropwizard.metrics.Meter;
import io.dropwizard.metrics.Metric;
import io.dropwizard.metrics.MetricFilter;
import io.dropwizard.metrics.MetricRegistry;
import io.dropwizard.metrics.MetricRegistryListener;
import io.dropwizard.metrics.MetricSet;
import io.dropwizard.metrics.Timer;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CopyOnWriteArrayList;
/**
* A registry of metric instances.
*/
public class MetricRegistry implements MetricSet {
/**
* @see #name(String, String...)
*/
public static MetricName name(Class<?> klass, String... names) {
return name(klass.getName(), names);
}
/**
* Shorthand method for backwards compatibility in creating metric names.
*
* Uses {@link MetricName#build(String...)} for its
* heavy lifting.
*
* @see MetricName#build(String...)
* @param name The first element of the name
* @param names The remaining elements of the name
* @return A metric name matching the specified components.
*/
public static MetricName name(String name, String... names) {
final int length;
if (names == null) {
length = 0;
} else {
length = names.length;
}
final String[] parts = new String[length + 1];
parts[0] = name;
for (int i = 0; i < length; i++) {
parts[i+1] = names[i];
}
return MetricName.build(parts);
}
private final ConcurrentMap<MetricName, Metric> metrics;
private final List<MetricRegistryListener> listeners;
/**
* Creates a new {@link MetricRegistry}.
*/
public MetricRegistry() {
this(new ConcurrentHashMap<MetricName, Metric>());
}
/**
* Creates a {@link MetricRegistry} with a custom {@link ConcurrentMap} implementation for use
* inside the registry. Call as the super-constructor to create a {@link MetricRegistry} with
* space- or time-bounded metric lifecycles, for example.
*/
protected MetricRegistry(ConcurrentMap<MetricName, Metric> metricsMap) {
this.metrics = metricsMap;
this.listeners = new CopyOnWriteArrayList<>();
}
/**
* @see #register(MetricName, Metric)
*/
@SuppressWarnings("unchecked")
public <T extends Metric> T register(String name, T metric) throws IllegalArgumentException {
return register(MetricName.build(name), metric);
}
/**
* Given a {@link Metric}, registers it under the given name.
*
* @param name the name of the metric
* @param metric the metric
* @param <T> the type of the metric
* @return {@code metric}
* @throws IllegalArgumentException if the name is already registered
*/
@SuppressWarnings("unchecked")
public <T extends Metric> T register(MetricName name, T metric) throws IllegalArgumentException {
if (metric instanceof MetricSet) {
registerAll(name, (MetricSet) metric);
} else {
final Metric existing = metrics.putIfAbsent(name, metric);
if (existing == null) {
onMetricAdded(name, metric);
} else {
throw new IllegalArgumentException("A metric named " + name + " already exists");
}
}
return metric;
}
/**
* Given a metric set, registers them.
*
* @param metrics a set of metrics
* @throws IllegalArgumentException if any of the names are already registered
*/
public void registerAll(MetricSet metrics) throws IllegalArgumentException {
registerAll(null, metrics);
}
/**
* @see #counter(MetricName)
*/
public Counter counter(String name) {
return counter(MetricName.build(name));
}
/**
* Return the {@link Counter} registered under this name; or create and register
* a new {@link Counter} if none is registered.
*
* @param name the name of the metric
* @return a new or pre-existing {@link Counter}
*/
public Counter counter(MetricName name) {
return getOrAdd(name, MetricBuilder.COUNTERS);
}
/**
* @see #histogram(MetricName)
*/
public Histogram histogram(String name) {
return histogram(MetricName.build(name));
}
/**
* Return the {@link Histogram} registered under this name; or create and register
* a new {@link Histogram} if none is registered.
*
* @param name the name of the metric
* @return a new or pre-existing {@link Histogram}
*/
public Histogram histogram(MetricName name) {
return getOrAdd(name, MetricBuilder.HISTOGRAMS);
}
/**
* @see #meter(MetricName)
*/
public Meter meter(String name) {
return meter(MetricName.build(name));
}
/**
* Return the {@link Meter} registered under this name; or create and register
* a new {@link Meter} if none is registered.
*
* @param name the name of the metric
* @return a new or pre-existing {@link Meter}
*/
public Meter meter(MetricName name) {
return getOrAdd(name, MetricBuilder.METERS);
}
/**
* @see #timer(MetricName)
*/
public Timer timer(String name) {
return timer(MetricName.build(name));
}
/**
* Return the {@link Timer} registered under this name; or create and register
* a new {@link Timer} if none is registered.
*
* @param name the name of the metric
* @return a new or pre-existing {@link Timer}
*/
public Timer timer(MetricName name) {
return getOrAdd(name, MetricBuilder.TIMERS);
}
/**
* Removes the metric with the given name.
*
* @param name the name of the metric
* @return whether or not the metric was removed
*/
public boolean remove(MetricName name) {
final Metric metric = metrics.remove(name);
if (metric != null) {
onMetricRemoved(name, metric);
return true;
}
return false;
}
/**
* Removes all metrics which match the given filter.
*
* @param filter a filter
* @return whether or not a metric was removed
*/
public boolean removeMatching(MetricFilter filter) {
boolean removed = false;
for (Map.Entry<MetricName, Metric> entry : metrics.entrySet()) {
if (filter.matches(entry.getKey(), entry.getValue())) {
removed |= remove(entry.getKey());
}
}
return removed;
}
/**
* Adds a {@link MetricRegistryListener} to a collection of listeners that will be notified on
* metric creation. Listeners will be notified in the order in which they are added.
* <p/>
* <b>N.B.:</b> The listener will be notified of all existing metrics when it first registers.
*
* @param listener the listener that will be notified
*/
public void addListener(MetricRegistryListener listener) {
listeners.add(listener);
for (Map.Entry<MetricName, Metric> entry : metrics.entrySet()) {
notifyListenerOfAddedMetric(listener, entry.getValue(), entry.getKey());
}
}
/**
* Removes a {@link MetricRegistryListener} from this registry's collection of listeners.
*
* @param listener the listener that will be removed
*/
public void removeListener(MetricRegistryListener listener) {
listeners.remove(listener);
}
/**
* Returns a set of the names of all the metrics in the registry.
*
* @return the names of all the metrics
*/
public SortedSet<MetricName> getNames() {
return Collections.unmodifiableSortedSet(new TreeSet<>(metrics.keySet()));
}
/**
* Returns a map of all the gauges in the registry and their names.
*
* @return all the gauges in the registry
*/
public SortedMap<MetricName, Gauge> getGauges() {
return getGauges(MetricFilter.ALL);
}
/**
* Returns a map of all the gauges in the registry and their names which match the given filter.
*
* @param filter the metric filter to match
* @return all the gauges in the registry
*/
public SortedMap<MetricName, Gauge> getGauges(MetricFilter filter) {
return getMetrics(Gauge.class, filter);
}
/**
* Returns a map of all the counters in the registry and their names.
*
* @return all the counters in the registry
*/
public SortedMap<MetricName, Counter> getCounters() {
return getCounters(MetricFilter.ALL);
}
/**
* Returns a map of all the counters in the registry and their names which match the given
* filter.
*
* @param filter the metric filter to match
* @return all the counters in the registry
*/
public SortedMap<MetricName, Counter> getCounters(MetricFilter filter) {
return getMetrics(Counter.class, filter);
}
/**
* Returns a map of all the histograms in the registry and their names.
*
* @return all the histograms in the registry
*/
public SortedMap<MetricName, Histogram> getHistograms() {
return getHistograms(MetricFilter.ALL);
}
/**
* Returns a map of all the histograms in the registry and their names which match the given
* filter.
*
* @param filter the metric filter to match
* @return all the histograms in the registry
*/
public SortedMap<MetricName, Histogram> getHistograms(MetricFilter filter) {
return getMetrics(Histogram.class, filter);
}
/**
* Returns a map of all the meters in the registry and their names.
*
* @return all the meters in the registry
*/
public SortedMap<MetricName, Meter> getMeters() {
return getMeters(MetricFilter.ALL);
}
/**
* Returns a map of all the meters in the registry and their names which match the given filter.
*
* @param filter the metric filter to match
* @return all the meters in the registry
*/
public SortedMap<MetricName, Meter> getMeters(MetricFilter filter) {
return getMetrics(Meter.class, filter);
}
/**
* Returns a map of all the timers in the registry and their names.
*
* @return all the timers in the registry
*/
public SortedMap<MetricName, Timer> getTimers() {
return getTimers(MetricFilter.ALL);
}
/**
* Returns a map of all the timers in the registry and their names which match the given filter.
*
* @param filter the metric filter to match
* @return all the timers in the registry
*/
public SortedMap<MetricName, Timer> getTimers(MetricFilter filter) {
return getMetrics(Timer.class, filter);
}
@SuppressWarnings("unchecked")
private <T extends Metric> T getOrAdd(MetricName name, MetricBuilder<T> builder) {
final Metric metric = metrics.get(name);
if (builder.isInstance(metric)) {
return (T) metric;
} else if (metric == null) {
try {
return register(name, builder.newMetric());
} catch (IllegalArgumentException e) {
final Metric added = metrics.get(name);
if (builder.isInstance(added)) {
return (T) added;
}
}
}
throw new IllegalArgumentException(name + " is already used for a different type of metric");
}
@SuppressWarnings("unchecked")
private <T extends Metric> SortedMap<MetricName, T> getMetrics(Class<T> klass, MetricFilter filter) {
final TreeMap<MetricName, T> timers = new TreeMap<>();
for (Map.Entry<MetricName, Metric> entry : metrics.entrySet()) {
if (klass.isInstance(entry.getValue()) && filter.matches(entry.getKey(),
entry.getValue())) {
timers.put(entry.getKey(), (T) entry.getValue());
}
}
return Collections.unmodifiableSortedMap(timers);
}
private void onMetricAdded(MetricName name, Metric metric) {
for (MetricRegistryListener listener : listeners) {
notifyListenerOfAddedMetric(listener, metric, name);
}
}
private void notifyListenerOfAddedMetric(MetricRegistryListener listener, Metric metric, MetricName name) {
if (metric instanceof Gauge) {
listener.onGaugeAdded(name, (Gauge<?>) metric);
} else if (metric instanceof Counter) {
listener.onCounterAdded(name, (Counter) metric);
} else if (metric instanceof Histogram) {
listener.onHistogramAdded(name, (Histogram) metric);
} else if (metric instanceof Meter) {
listener.onMeterAdded(name, (Meter) metric);
} else if (metric instanceof Timer) {
listener.onTimerAdded(name, (Timer) metric);
} else {
throw new IllegalArgumentException("Unknown metric type: " + metric.getClass());
}
}
private void onMetricRemoved(MetricName name, Metric metric) {
for (MetricRegistryListener listener : listeners) {
notifyListenerOfRemovedMetric(name, metric, listener);
}
}
private void notifyListenerOfRemovedMetric(MetricName name, Metric metric, MetricRegistryListener listener) {
if (metric instanceof Gauge) {
listener.onGaugeRemoved(name);
} else if (metric instanceof Counter) {
listener.onCounterRemoved(name);
} else if (metric instanceof Histogram) {
listener.onHistogramRemoved(name);
} else if (metric instanceof Meter) {
listener.onMeterRemoved(name);
} else if (metric instanceof Timer) {
listener.onTimerRemoved(name);
} else {
throw new IllegalArgumentException("Unknown metric type: " + metric.getClass());
}
}
private void registerAll(MetricName prefix, MetricSet metrics) throws IllegalArgumentException {
if (prefix == null)
prefix = MetricName.EMPTY;
for (Map.Entry<MetricName, Metric> entry : metrics.getMetrics().entrySet()) {
if (entry.getValue() instanceof MetricSet) {
registerAll(MetricName.join(prefix, entry.getKey()), (MetricSet) entry.getValue());
} else {
register(MetricName.join(prefix, entry.getKey()), entry.getValue());
}
}
}
@Override
public Map<MetricName, Metric> getMetrics() {
return Collections.unmodifiableMap(metrics);
}
/**
* A quick and easy way of capturing the notion of default metrics.
*/
private interface MetricBuilder<T extends Metric> {
MetricBuilder<Counter> COUNTERS = new MetricBuilder<Counter>() {
@Override
public Counter newMetric() {
return new Counter();
}
@Override
public boolean isInstance(Metric metric) {
return Counter.class.isInstance(metric);
}
};
MetricBuilder<Histogram> HISTOGRAMS = new MetricBuilder<Histogram>() {
@Override
public Histogram newMetric() {
return new Histogram(new ExponentiallyDecayingReservoir());
}
@Override
public boolean isInstance(Metric metric) {
return Histogram.class.isInstance(metric);
}
};
MetricBuilder<Meter> METERS = new MetricBuilder<Meter>() {
@Override
public Meter newMetric() {
return new Meter();
}
@Override
public boolean isInstance(Metric metric) {
return Meter.class.isInstance(metric);
}
};
MetricBuilder<Timer> TIMERS = new MetricBuilder<Timer>() {
@Override
public Timer newMetric() {
return new Timer();
}
@Override
public boolean isInstance(Metric metric) {
return Timer.class.isInstance(metric);
}
};
T newMetric();
boolean isInstance(Metric metric);
}
}