4.x: Neutral metrics API - revise MetricsFeature and rework Prometheus and JSON formatting

bom/pom.xml

@@ -379,6 +379,16 @@
                 <artifactId>helidon-metrics-api</artifactId>
                 <version>${helidon.version}</version>
             </dependency>
+            <dependency>
+                <groupId>io.helidon.metrics</groupId>
+                <artifactId>helidon-metrics-testing</artifactId>
+                <version>${helidon.version}</version>
+            </dependency>
+            <dependency>
+                <groupId>io.helidon.metrics</groupId>
+                <artifactId>helidon-metrics-micrometer</artifactId>
+                <version>${helidon.version}</version>
+            </dependency>
             <dependency>
                 <groupId>io.helidon.metrics</groupId>
                 <artifactId>helidon-metrics-service-api</artifactId>

dependencies/pom.xml

@@ -98,8 +98,8 @@
         <version.lib.logback>1.4.0</version.lib.logback>
         <version.lib.mariadb-java-client>2.6.2</version.lib.mariadb-java-client>
         <version.lib.maven-wagon>2.10</version.lib.maven-wagon>
-        <version.lib.micrometer>1.11.1</version.lib.micrometer>
-        <version.lib.micrometer-prometheus>1.11.1</version.lib.micrometer-prometheus>
+        <version.lib.micrometer>1.11.3</version.lib.micrometer>
+        <version.lib.micrometer-prometheus>1.11.3</version.lib.micrometer-prometheus>
         <version.lib.micronaut>3.4.3</version.lib.micronaut>
         <version.lib.micronaut.data>3.3.0</version.lib.micronaut.data>
         <version.lib.micronaut.sql>4.4.0</version.lib.micronaut.sql>

metrics/api/pom.xml

@@ -41,6 +41,20 @@
             <groupId>io.helidon.common</groupId>
             <artifactId>helidon-common-config</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.helidon.builder</groupId>
+            <artifactId>helidon-builder-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.inject.configdriven</groupId>
+            <artifactId>helidon-inject-configdriven-api</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.inject.configdriven</groupId>
+            <artifactId>helidon-inject-configdriven-runtime</artifactId>
+            <optional>true</optional>
+        </dependency>
         <dependency>
             <groupId>io.helidon.config</groupId>
             <artifactId>helidon-config-metadata</artifactId>
@@ -50,13 +64,10 @@
             <groupId>org.eclipse.microprofile.metrics</groupId>
             <artifactId>microprofile-metrics-api</artifactId>
         </dependency>
-        <dependency>
-            <groupId>io.micrometer</groupId>
-            <artifactId>micrometer-core</artifactId>
-        </dependency>
         <dependency>
             <groupId>io.helidon.common.testing</groupId>
             <artifactId>helidon-common-testing-junit5</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
@@ -88,11 +99,26 @@
                 <configuration>
                     <forceJavacCompilerUse>true</forceJavacCompilerUse>
                     <annotationProcessorPaths>
+                        <path>
+                            <groupId>io.helidon.common.features</groupId>
+                            <artifactId>helidon-common-features-processor</artifactId>
+                            <version>${helidon.version}</version>
+                        </path>
                         <path>
                             <groupId>io.helidon.config</groupId>
                             <artifactId>helidon-config-metadata-processor</artifactId>
                             <version>${helidon.version}</version>
                         </path>
+                        <path>
+                            <groupId>io.helidon.inject.configdriven</groupId>
+                            <artifactId>helidon-inject-configdriven-processor</artifactId>
+                            <version>${helidon.version}</version>
+                        </path>
+                        <path>
+                            <groupId>io.helidon.builder</groupId>
+                            <artifactId>helidon-builder-processor</artifactId>
+                            <version>${helidon.version}</version>
+                        </path>
                     </annotationProcessorPaths>
                 </configuration>
             </plugin>

metrics/api/src/main/java/io/helidon/metrics/api/Bucket.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2023 Oracle and/or its affiliates.
+ *
+ * Licensed 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 "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.metrics.api;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Representation of a histogram bucket, including the boundary value and the count of observations in that bucket.
+ * <p>
+ *     The boundary value is an upper bound on the observation values that can occupy the bucket.
+ *     That is, an observation occupies a bucket if its value is less than or equal to the bucket's boundary value.
+ * </p>
+ */
+public interface Bucket extends Wrapper {
+
+    /**
+     * Returns the bucket boundary.
+     *
+     * @return bucket boundary value
+     */
+    double boundary();
+
+    /**
+     * Returns the bucket boundary interpreted as a time in nanoseconds and expressed in the specified
+     * {@link java.util.concurrent.TimeUnit}.
+     *
+     * @param unit time unit in which to express the bucket boundary
+     * @return bucket boundary value
+     */
+    double boundary(TimeUnit unit);
+
+    /**
+     * Returns the number of observations in the bucket.
+     *
+     * @return observation count for the bucket
+     */
+    long count();
+}

metrics/api/src/main/java/io/helidon/metrics/api/Clock.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2023 Oracle and/or its affiliates.
+ *
+ * Licensed 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 "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.metrics.api;
+
+/**
+ * Reports absolute time (and, therefore, is also useful in computing elapsed times).
+ */
+public interface Clock extends Wrapper {
+
+    /**
+     * Returns the system clock for the Helidon metrics implementation.
+     * <p>
+     *     The system clock methods are functionally equivalent to {@link System#currentTimeMillis()}
+     *     and {@link System#nanoTime()}.
+     * </p>
+     *
+     * @return the system clock
+     */
+    static Clock system() {
+        return MetricsFactoryManager.getInstance().clockSystem();
+    }
+
+    /**
+     * Returns the current wall time in milliseconds since the epoch.
+     *
+     * <p>
+     *     Typically equivalent to {@link System#currentTimeMillis()}. Should not be used to determine durations.
+     *     For that use {@link #monotonicTime()} instead.
+     * </p>
+     *
+     * @return wall time in milliseconds
+     */
+    long wallTime();
+
+    /**
+     * Returns the current time in nanoseconds from a monotonic clock source.
+     *
+     * <p>
+     *     The value is only meaningful when compared with another value returned from this method to determine the elapsed time
+     *     for an operation. The difference between two samples will have a unit of nanoseconds. The returned value is
+     *     typically equivalent to {@link System#nanoTime()}.
+     * </p>
+     *
+     * @return monotonic time in nanoseconds
+     */
+    long monotonicTime();
+
+    /**
+     * Unwraps the clock to the specified type (typically not needed for custom clocks).
+     *
+     * @param c {@link Class} to which to cast this object
+     * @return unwrapped clock
+     * @param <R> the type of the unwrapped clock
+     */
+    @Override
+    default <R> R unwrap(Class<? extends R> c) {
+        throw new UnsupportedOperationException();
+    }
+}

metrics/api/src/main/java/io/helidon/metrics/api/Counter.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2023 Oracle and/or its affiliates.
+ *
+ * Licensed 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 "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.metrics.api;
+
+/**
+ * Records a monotonically increasing value.
+ */
+public interface Counter extends Meter {
+
+    /**
+     * Creates a new builder for a counter.
+     *
+     * @param name counter name
+     * @return new builder
+     */
+    static Builder builder(String name) {
+        return MetricsFactory.getInstance().counterBuilder(name);
+    }
+
+
+    /**
+     * Updates the counter by one.
+     */
+    void increment();
+
+    /**
+     * Updates the counter by the specified amount which should be non-negative.
+     *
+     * @param amount amount to add to the counter.
+     */
+    void increment(long amount);
+
+    /**
+     * Returns the cumulative count since this counter was registered.
+     *
+     * @return cumulative count since this counter was registered
+     */
+    long count();
+
+    /**
+     * Builder for a new counter.
+     */
+    interface Builder extends Meter.Builder<Builder, Counter> {
+    }
+}