ISPN-15029 Create metrics for latency between nodes

Other side changes included in this PR are
* Publish percentiles for histograms
* Added remaining Micrometer meters (Counter, FunctionTimer,
  DistributionSummary)
* Extract logic from MetricsCollector to a new class MetricsRegistry

build/component-processor/src/main/java/org/infinispan/component/processor/external/JGroupsComponentProcessor.java

@@ -65,15 +65,16 @@ public void generate(PrintWriter w, String packageName, String className) throws
       w.println("import java.util.Map;");
       w.println("import java.util.function.Function;");
       w.println("import javax.annotation.processing.Generated;");
-      w.println("import static org.infinispan.factories.impl.MBeanMetadata.AttributeMetadata;");
+      w.println("import org.infinispan.commons.stat.GaugeMetricInfo;");
+      w.println("import org.infinispan.commons.stat.MetricInfo;");
       w.println("import org.jgroups.stack.Protocol;");
       w.println();
       w.printf("@Generated(value = \"%s\", date = \"%s\")%n", getClass().getName(), Instant.now().toString());
       w.printf("public class %s {%n", className);
-      w.println("   public static final Map<Class<? extends Protocol>, Collection<AttributeMetadata>> PROTOCOL_METADATA = new HashMap<>();");
+      w.println("   public static final Map<Class<? extends Protocol>, Collection<MetricInfo>> PROTOCOL_METADATA = new HashMap<>();");
       w.printf("   private %s() {}%n", className);
       w.println("   static {");
-      w.println("      List<AttributeMetadata> attributes;");
+      w.println("      List<MetricInfo> attributes;");
       for (short id = 0; id < 256; id++) {
          Class<?> protocol = ClassConfigurator.getProtocol(id);
          addProtocol(protocol, w);
@@ -105,9 +106,8 @@ private static void addProtocol(Class<?> protocol, PrintWriter w) {
             if (hasAttributes.compareAndSet(false, true)) {
                w.println("      attributes = new ArrayList<>();");
             }
-            w.printf("      attributes.add(new AttributeMetadata(\"%s\", \"%s\", false, false, \"%s\",\n" +
-                        "                               false, (Function<%s, ?>) %s::%s, null));%n",
-                  method.getName(), annotation.description().replace('"', '\''), method.getReturnType().getName(), protocol.getName(), protocol.getName(), method.getName());
+            w.printf("      attributes.add(new GaugeMetricInfo<>(\"%s\", \"%s\", null, %s::%s));%n",
+                  method.getName(), annotation.description().replace('"', '\''), protocol.getName(), method.getName());
          }
       }
 
@@ -133,9 +133,8 @@ private static void addTPComponent(String getterMethodName, Class<?> protocol, C
             if (hasAttributes.compareAndSet(false, true)) {
                w.println("      attributes = new ArrayList<>();");
             }
-            w.printf("      attributes.add(new AttributeMetadata(\"%s\", \"%s\", false, false, \"%s\",\n" +
-                        "                               false, (Function<%s, ?>) p -> p.%s().%s(), null));%n",
-                  method.getName(), annotation.description().replace('"', '\''), method.getReturnType().getName(), protocol.getName(), getterMethodName, method.getName());
+            w.printf("      attributes.add(new GaugeMetricInfo<>(\"%s\", \"%s\", null, ((Function<%s, Number>) p -> p.%s().%s())));%n",
+                  method.getName(), annotation.description().replace('"', '\''), protocol.getName(), getterMethodName, method.getName());
          }
       }
    }

commons/all/src/main/java/org/infinispan/commons/stat/BaseMetricInfo.java

@@ -0,0 +1,47 @@
+package org.infinispan.commons.stat;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Base implementation of {@link MetricInfo} with all the required information.
+ *
+ * @since 15.0
+ */
+abstract class BaseMetricInfo implements MetricInfo {
+
+   private final String name;
+   private final String description;
+   private final Map<String, String> map;
+
+   BaseMetricInfo(String name, String description, Map<String, String> map) {
+      this.name = Objects.requireNonNull(name);
+      this.description = Objects.requireNonNull(description);
+      this.map = map == null || map.isEmpty() ? Collections.emptyMap() : Map.copyOf(map);
+   }
+
+   @Override
+   public final String getName() {
+      return name;
+   }
+
+   @Override
+   public final String getDescription() {
+      return description;
+   }
+
+   @Override
+   public final Map<String, String> getTags() {
+      return map;
+   }
+
+   @Override
+   public String toString() {
+      return getClass().getSimpleName() + "{" +
+            "name='" + getName() + '\'' +
+            ", description='" + getDescription() + '\'' +
+            ", tags=" + getTags() +
+            '}';
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/BaseSetterMetricInfo.java

@@ -0,0 +1,24 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.function.BiConsumer;
+
+/**
+ * Extends {@link BaseMetricInfo} with a consumer, usually a target instance and the tracker to set.
+ *
+ * @since 15.0
+ */
+abstract class BaseSetterMetricInfo<O, M> extends BaseMetricInfo {
+
+   private final BiConsumer<O, M> setter;
+
+   BaseSetterMetricInfo(String name, String description, Map<String, String> map, BiConsumer<O, M> setter) {
+      super(name, description, map);
+      this.setter = Objects.requireNonNull(setter);
+   }
+
+   public final void accept(O targetInstance, M metricTracker) {
+      setter.accept(targetInstance, metricTracker);
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/CounterMetricInfo.java

@@ -0,0 +1,19 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.function.BiConsumer;
+
+/**
+ * Represents a counter. It sets {@link CounterTracker} into the target instance.
+ * <p>
+ * A counter tracks a monotonically increasing values and never resets to a lesser value.
+ *
+ * @since 15.0
+ */
+public final class CounterMetricInfo<T> extends BaseSetterMetricInfo<T, CounterTracker> {
+
+   public CounterMetricInfo(String name, String description, Map<String, String> map, BiConsumer<T, CounterTracker> setter) {
+      super(name, description, map, setter);
+   }
+
+}

commons/all/src/main/java/org/infinispan/commons/stat/CounterTracker.java

@@ -0,0 +1,22 @@
+package org.infinispan.commons.stat;
+
+/**
+ * Tracks a monotonically increasing values.
+ * <p>
+ * The counters may never be reset to a lesser value.
+ */
+public interface CounterTracker {
+
+   /**
+    * Update the counter by one.
+    */
+   void increment();
+
+   /**
+    * Update the counter by {@code amount}.
+    *
+    * @param amount The amount to add to the counter.
+    */
+   void increment(double amount);
+
+}

commons/all/src/main/java/org/infinispan/commons/stat/DistributionSummaryMetricInfo.java

@@ -0,0 +1,18 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.function.BiConsumer;
+
+/**
+ * Represents a distribution summary (histogram). It sets {@link DistributionSummaryTracker} into the target instance.
+ * <p>
+ * A distribution summary tracks the sample distribution of events.
+ *
+ * @since 15.0
+ */
+public final class DistributionSummaryMetricInfo<T> extends BaseSetterMetricInfo<T, DistributionSummaryTracker> {
+
+   public DistributionSummaryMetricInfo(String name, String description, Map<String, String> map, BiConsumer<T, DistributionSummaryTracker> setter) {
+      super(name, description, map, setter);
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/DistributionSummaryTracker.java

@@ -0,0 +1,15 @@
+package org.infinispan.commons.stat;
+
+/**
+ * Track the sample distribution of events.
+ */
+public interface DistributionSummaryTracker {
+
+   /**
+    * Updates the statistics kept by the summary with the specified amount.
+    *
+    * @param amount Amount for an event being tracked.
+    */
+   void record(double amount);
+
+}

commons/all/src/main/java/org/infinispan/commons/stat/FunctionTimerMetricInfo.java

@@ -0,0 +1,41 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.TimeUnit;
+import java.util.function.BiConsumer;
+
+/**
+ * Represents a duration metric. It sets {@link TimerTracker} into the target instance.
+ * <p>
+ * A distribution summary tracks a duration.
+ *
+ * @since 15.0
+ */
+public final class FunctionTimerMetricInfo<T> extends BaseSetterMetricInfo<T, TimerTracker> {
+
+   private final TimeUnit timeUnit;
+
+   public FunctionTimerMetricInfo(String name, String description, Map<String, String> map, BiConsumer<T, TimerTracker> setter, TimeUnit timeUnit) {
+      super(name, description, map, setter);
+      this.timeUnit = Objects.requireNonNull(timeUnit);
+   }
+
+   /**
+    * @return The {@link TimeUnit} of the time tracked by the event.
+    */
+   public TimeUnit getTimeUnit() {
+      return timeUnit;
+   }
+
+   @Override
+   public String toString() {
+      return "FunctionTimerMetricInfo{" +
+            "name='" + getName() + '\'' +
+            ", timeUnit=" + timeUnit +
+            ", description='" + getDescription() + '\'' +
+            ", tags=" + getTags() +
+            '}';
+   }
+
+}

commons/all/src/main/java/org/infinispan/commons/stat/GaugeMetricInfo.java

@@ -0,0 +1,30 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+/**
+ * Represents a gauge metric.
+ * <p>
+ * A gauge tracks a specific value, like a queue size.
+ *
+ * @since 15.0
+ */
+public final class GaugeMetricInfo<T> extends BaseMetricInfo {
+
+   private final Function<T, Number> function;
+
+   public GaugeMetricInfo(String name, String description, Map<String, String> map, Function<T, Number> function) {
+      super(name, description, map);
+      this.function = Objects.requireNonNull(function);
+   }
+
+   /**
+    * @return The {@link Supplier} to be invoked to fetch the value from {@code instance}.
+    */
+   public Supplier<Number> getGauge(T instance) {
+      return () -> function.apply(instance);
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/MetricInfo.java

@@ -0,0 +1,31 @@
+package org.infinispan.commons.stat;
+
+import java.util.Collections;
+import java.util.Map;
+
+/**
+ * Class that represent the information about a metrics.
+ * <p>
+ * Includes the metrics's name, description and tags. Subclasses can add more information about it.
+ *
+ * @since 15.0
+ */
+public interface MetricInfo {
+
+   /**
+    * @return The metrics name.
+    */
+   String getName();
+
+   /**
+    * @return The metrics description/help message.
+    */
+   String getDescription();
+
+   /**
+    * @return The tags to be used. Must be non-null.
+    */
+   default Map<String, String> getTags() {
+      return Collections.emptyMap();
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/TimeGaugeMetricInfo.java

@@ -0,0 +1,38 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+/**
+ * Same as {@link GaugeMetricInfo} but the tracked value is a time or duration.
+ *
+ * @since 15.0
+ */
+public final class TimeGaugeMetricInfo<T> extends BaseMetricInfo {
+
+   private final Function<T, Number> function;
+   private final TimeUnit timeUnit;
+
+   public TimeGaugeMetricInfo(String name, String description, Map<String, String> map, Function<T, Number> function, TimeUnit timeUnit) {
+      super(name, description, map);
+      this.function = Objects.requireNonNull(function);
+      this.timeUnit = Objects.requireNonNull(timeUnit);
+   }
+
+   /**
+    * @return The {@link Supplier} to invoke to return the current value of the metric.
+    */
+   public Supplier<Number> getGauge(T instance) {
+      return () -> function.apply(instance);
+   }
+
+   /**
+    * @return The {@link TimeUnit} of the tracked value.
+    */
+   public TimeUnit getTimeUnit() {
+      return timeUnit;
+   }
+}

commons/all/src/main/java/org/infinispan/commons/stat/TimerMetricInfo.java

@@ -0,0 +1,16 @@
+package org.infinispan.commons.stat;
+
+import java.util.Map;
+import java.util.function.BiConsumer;
+
+/**
+ * Represents a duration event (histogram). It sets {@link TimerTracker} into the target instance.
+ *
+ * @since 15.0
+ */
+public final class TimerMetricInfo<T> extends BaseSetterMetricInfo<T, TimerTracker> {
+
+   public TimerMetricInfo(String name, String description, Map<String, String> map, BiConsumer<T, TimerTracker> setter) {
+      super(name, description, map, setter);
+   }
+}