Performance Metrics service and manager added
diff --git a/utils/misc/src/main/java/org/onlab/metrics/MetricsManager.java b/utils/misc/src/main/java/org/onlab/metrics/MetricsManager.java
new file mode 100644
index 0000000..08f8b11
--- /dev/null
+++ b/utils/misc/src/main/java/org/onlab/metrics/MetricsManager.java
@@ -0,0 +1,249 @@
+package org.onlab.metrics;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import com.codahale.metrics.Counter;
+import com.codahale.metrics.Gauge;
+import com.codahale.metrics.Histogram;
+import com.codahale.metrics.Meter;
+import com.codahale.metrics.Metric;
+import com.codahale.metrics.MetricFilter;
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.Timer;
+
+/**
+ * This class holds the Metrics registry for ONOS.
+ * All metrics (Counter, Histogram, Timer, Meter, Gauge) use a hierarchical
+ * string-based naming scheme: COMPONENT.FEATURE.NAME.
+ * Example: "Topology.Counters.TopologyUpdates".
+ * The COMPONENT and FEATURE names have to be registered in advance before
+ * a metric can be created. Example:
+ * <pre>
+ * <code>
+ * private final MetricsManager.MetricsComponent COMPONENT =
+ * MetricsManager.registerComponent("Topology");
+ * private final MetricsManager.MetricsFeature FEATURE =
+ * COMPONENT.registerFeature("Counters");
+ * private final Counter counterTopologyUpdates =
+ * MetricsManager.createCounter(COMPONENT, FEATURE, "TopologyUpdates");
+ * </code>
+ * </pre>
+ * Gauges are slightly different because they are not created directly in
+ * this class, but are allocated by the caller and passed in for registration:
+ * <pre>
+ * <code>
+ * private final Gauge<Long> gauge =
+ * new {@literal Gauge<Long>}() {
+ * {@literal @}Override
+ * public Long getValue() {
+ * return gaugeValue;
+ * }
+ * };
+ * MetricsManager.registerMetric(COMPONENT, FEATURE, GAUGE_NAME, gauge);
+ * </code>
+ * </pre>
+ */
+public final class MetricsManager implements MetricsService {
+
+ /**
+ * Registry to hold the Components defined in the system.
+ */
+ private ConcurrentMap<String, MetricsComponent> componentsRegistry =
+ new ConcurrentHashMap<>();
+
+ /**
+ * Registry for the Metrics objects created in the system.
+ */
+ private final MetricRegistry metricsRegistry = new MetricRegistry();
+
+ /**
+ * Hide constructor. The only way to get the registry is through the
+ * singleton getter.
+ */
+ private MetricsManager() {}
+
+ /**
+ * Registers a component.
+ *
+ * @param name name of the Component to register
+ * @return MetricsComponent object that can be used to create Metrics.
+ */
+ public MetricsComponent registerComponent(final String name) {
+ MetricsComponent component = componentsRegistry.get(name);
+ if (component == null) {
+ final MetricsComponent createdComponent = new MetricsComponent(name);
+ component = componentsRegistry.putIfAbsent(name, createdComponent);
+ if (component == null) {
+ component = createdComponent;
+ }
+ }
+ return component;
+ }
+
+ /**
+ * Generates a name for a Metric from its component and feature.
+ *
+ * @param component component the metric is defined in
+ * @param feature feature the metric is defined in
+ * @param metricName local name of the metric
+ *
+ * @return full name of the metric
+ */
+ public String generateName(final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName) {
+ return MetricRegistry.name(component.getName(),
+ feature.getName(),
+ metricName);
+ }
+
+ /**
+ * Creates a Counter metric.
+ *
+ * @param component component the Counter is defined in
+ * @param feature feature the Counter is defined in
+ * @param metricName local name of the metric
+ * @return the created Counter Meteric
+ */
+ public Counter createCounter(final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName) {
+ final String name = generateName(component, feature, metricName);
+ return metricsRegistry.counter(name);
+ }
+
+ /**
+ * Creates a Histogram metric.
+ *
+ * @param component component the Histogram is defined in
+ * @param feature feature the Histogram is defined in
+ * @param metricName local name of the metric
+ * @return the created Histogram Metric
+ */
+ public Histogram createHistogram(final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName) {
+ final String name = generateName(component, feature, metricName);
+ return metricsRegistry.histogram(name);
+ }
+
+ /**
+ * Creates a Timer metric.
+ *
+ * @param component component the Timer is defined in
+ * @param feature feature the Timeer is defined in
+ * @param metricName local name of the metric
+ * @return the created Timer Metric
+ */
+ public Timer createTimer(final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName) {
+ final String name = generateName(component, feature, metricName);
+ return metricsRegistry.timer(name);
+ }
+
+ /**
+ * Creates a Meter metric.
+ *
+ * @param component component the Meter is defined in
+ * @param feature feature the Meter is defined in
+ * @param metricName local name of the metric
+ * @return the created Meter Metric
+ */
+ public Meter createMeter(final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName) {
+ final String name = generateName(component, feature, metricName);
+ return metricsRegistry.meter(name);
+ }
+
+ /**
+ * Registers an already created Metric. This is used for situation where a
+ * caller needs to allocate its own Metric, but still register it with the
+ * system.
+ *
+ * @param <T> Metric type
+ * @param component component the Metric is defined in
+ * @param feature feature the Metric is defined in
+ * @param metricName local name of the metric
+ * @param metric Metric to register
+ * @return the registered Metric
+ */
+ public <T extends Metric> T registerMetric(
+ final MetricsComponent component,
+ final MetricsFeature feature,
+ final String metricName,
+ final T metric) {
+ final String name = generateName(component, feature, metricName);
+ metricsRegistry.register(name, metric);
+ return metric;
+ }
+
+ /**
+ * Fetches the existing Timers.
+ *
+ * @param filter filter to use to select Timers
+ * @return a map of the Timers that match the filter, with the key as the
+ * name String to the Timer.
+ */
+ public Map<String, Timer> getTimers(final MetricFilter filter) {
+ return metricsRegistry.getTimers(filter);
+ }
+
+ /**
+ * Fetches the existing Gauges.
+ *
+ * @param filter filter to use to select Gauges
+ * @return a map of the Gauges that match the filter, with the key as the
+ * name String to the Gauge.
+ */
+ @SuppressWarnings("rawtypes")
+ public Map<String, Gauge> getGauges(final MetricFilter filter) {
+ return metricsRegistry.getGauges(filter);
+ }
+
+ /**
+ * Fetches the existing Counters.
+ *
+ * @param filter filter to use to select Counters
+ * @return a map of the Counters that match the filter, with the key as the
+ * name String to the Counter.
+ */
+ public Map<String, Counter> getCounters(final MetricFilter filter) {
+ return metricsRegistry.getCounters(filter);
+ }
+
+ /**
+ * Fetches the existing Meters.
+ *
+ * @param filter filter to use to select Meters
+ * @return a map of the Meters that match the filter, with the key as the
+ * name String to the Meter.
+ */
+ public Map<String, Meter> getMeters(final MetricFilter filter) {
+ return metricsRegistry.getMeters(filter);
+ }
+
+ /**
+ * Fetches the existing Histograms.
+ *
+ * @param filter filter to use to select Histograms
+ * @return a map of the Histograms that match the filter, with the key as the
+ * name String to the Histogram.
+ */
+ public Map<String, Histogram> getHistograms(final MetricFilter filter) {
+ return metricsRegistry.getHistograms(filter);
+ }
+
+ /**
+ * Removes all Metrics that match a given filter.
+ *
+ * @param filter filter to use to select the Metrics to remove.
+ */
+ public void removeMatching(final MetricFilter filter) {
+ metricsRegistry.removeMatching(filter);
+ }
+}
+