support prometheus metric

Signed-off-by: zwmagic <[email protected]>

sermant-agentcore/sermant-agentcore-config/config/config.properties

@@ -36,6 +36,8 @@ agent.service.dynamic.config.enable=true
 agent.service.httpserver.enable=false
 # xDS service switch
 agent.service.xds.service.enable=false
+# Metric service switch
+agent.service.metric.enable=false
 #============================= Event configuration =============================#
 # Event switch
 event.enable=false

sermant-agentcore/sermant-agentcore-core/src/main/java/io/sermant/core/service/ServiceConfig.java

@@ -49,6 +49,9 @@ public class ServiceConfig implements BaseConfig {
     @ConfigFieldKey("xds.service.enable")
     private boolean xdsServiceEnable = false;
 
+    @ConfigFieldKey("metric.enable")
+    private boolean metricEnable = false;
+
     public boolean isHeartBeatEnable() {
         return heartBeatEnable;
     }
@@ -105,6 +108,14 @@ public void setXdsServiceEnable(boolean xdsServiceEnable) {
         this.xdsServiceEnable = xdsServiceEnable;
     }
 
+    public boolean isMetricEnable() {
+        return metricEnable;
+    }
+
+    public void setMetricEnable(boolean metricEnable) {
+        this.metricEnable = metricEnable;
+    }
+
     /**
      * Check whether the service of the given class name is enabled.
      *
@@ -133,6 +144,9 @@ public boolean checkServiceEnable(String serviceName) {
         if (ServiceManager.XDS_CORE_SERVICE_IMPL.equals(serviceName)) {
             return isXdsServiceEnable();
         }
+        if (ServiceManager.METRIC_SERVICE_IMPL.equals(serviceName)) {
+            return isMetricEnable();
+        }
         return false;
     }
 }

sermant-agentcore/sermant-agentcore-core/src/main/java/io/sermant/core/service/ServiceManager.java

@@ -91,6 +91,12 @@ public class ServiceManager {
     public static final String XDS_CORE_SERVICE_IMPL =
             "io.sermant.implement.service.xds.XdsCoreServiceImpl";
 
+    /**
+     * Metric Service Discover
+     */
+    public static final String METRIC_SERVICE_IMPL =
+            "io.sermant.implement.service.metrics.MeterMetricServiceImpl";
+
     /**
      * logger
      */

sermant-agentcore/sermant-agentcore-core/src/main/java/io/sermant/core/service/metric/api/Counter.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2017 VMware, Inc.
+ *
+ * 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
+ *
+ * https://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.
+ */
+
+/*
+ * Based on io/micrometer/core/instrument/Counter.java
+ * from the Micrometer project.
+ */
+
+package io.sermant.core.service.metric.api;
+
+/**
+ * metric Counter interface
+ *
+ * @author zwmagic
+ * @since 2024-08-16
+ */
+public interface Counter {
+    /**
+     * Update the counter by one.
+     */
+    default void increment() {
+        increment(1.0);
+    }
+
+    /**
+     * Update the counter by {@code amount}.
+     *
+     * @param amount Amount to add to the counter.
+     */
+    void increment(double amount);
+
+    /**
+     * get the counter value
+     *
+     * @return The cumulative count since this counter was created.
+     */
+    double count();
+}

sermant-agentcore/sermant-agentcore-core/src/main/java/io/sermant/core/service/metric/api/DistributionStatisticConfig.java

@@ -0,0 +1,226 @@
+/*
+ * Copyright 2017 VMware, Inc.
+ *
+ * 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
+ *
+ * https://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.
+ */
+
+/*
+ * Based on io/micrometer/core/instrument/distribution/DistributionStatisticConfig.java
+ * from the Micrometer project.
+ */
+
+package io.sermant.core.service.metric.api;
+
+import java.time.Duration;
+
+/**
+ * DistributionStatisticConfig
+ *
+ * @author zwmagic
+ * @since 2024-08-17
+ */
+public class DistributionStatisticConfig {
+    private static final Integer EXPIRY_MINUTE = 2;
+
+    /**
+     * Defines a static final constant named DEFAULT, which represents a distribution statistic configuration. This
+     * configuration controls and describes various aspects of data distribution statistics, such as the publication of
+     * percentile histograms, the precision of percentiles, and the expected value range. These configurations are
+     * useful for monitoring and analyzing data distributions, particularly in system performance monitoring and log
+     * analysis.
+     */
+    public static final DistributionStatisticConfig DEFAULT =
+            new DistributionStatisticConfig().publishPercentileHistogram(false)
+                    .percentilePrecision(1).minimumExpectedValue(1.0).maximumExpectedValue(Double.POSITIVE_INFINITY)
+                    .distributionStatisticExpiry(Duration.ofMinutes(EXPIRY_MINUTE))
+                    .distributionStatisticBufferLength(3);
+
+    private Boolean percentileHistogram;
+
+    private double[] percentiles;
+
+    private Integer percentilePrecision;
+
+    private Double minimumExpectedValue;
+
+    private Double maximumExpectedValue;
+
+    private Duration expiry;
+
+    private Integer bufferLength;
+
+    /**
+     * Gets the percentile histogram flag.
+     *
+     * @return the percentile histogram flag
+     */
+    public Boolean getPercentileHistogram() {
+        return percentileHistogram;
+    }
+
+    /**
+     * Gets the array of percentiles.
+     *
+     * @return the array of percentiles
+     */
+    public double[] getPercentiles() {
+        return percentiles;
+    }
+
+    /**
+     * Gets the precision for percentiles.
+     *
+     * @return the precision for percentiles
+     */
+    public Integer getPercentilePrecision() {
+        return percentilePrecision;
+    }
+
+    /**
+     * Gets the minimum expected value.
+     *
+     * @return the minimum expected value
+     */
+    public Double getMinimumExpectedValue() {
+        return minimumExpectedValue;
+    }
+
+    /**
+     * Gets the maximum expected value.
+     *
+     * @return the maximum expected value
+     */
+    public Double getMaximumExpectedValue() {
+        return maximumExpectedValue;
+    }
+
+    /**
+     * Gets the expiry duration.
+     *
+     * @return the expiry duration
+     */
+    public Duration getExpiry() {
+        return expiry;
+    }
+
+    /**
+     * Gets the length of the buffer.
+     *
+     * @return the length of the buffer
+     */
+    public Integer getBufferLength() {
+        return bufferLength;
+    }
+
+    /**
+     * Produces an additional time series for each requested percentile. This percentile is computed locally, and so
+     * can't be aggregated with percentiles computed across other dimensions (e.g. in a different instance). Use
+     * {@link #publishPercentileHistogram()} to publish a histogram that can be used to generate aggregable percentile
+     * approximations.
+     *
+     * @param percentilesValue Percentiles to compute and publish. The 95th percentile should be expressed as
+     * {@code 0.95}.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig publishPercentiles(double[] percentilesValue) {
+        this.percentiles = percentilesValue;
+        return this;
+    }
+
+    /**
+     * Adds histogram buckets used to generate aggregable percentile approximations in monitoring systems that have
+     * query facilities to do so (e.g. Prometheus' {@code histogram_quantile}, Atlas' {@code :percentiles}).
+     *
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig publishPercentileHistogram() {
+        return publishPercentileHistogram(true);
+    }
+
+    /**
+     * Adds histogram buckets used to generate aggregable percentile approximations in monitoring systems that have
+     * query facilities to do so (e.g. Prometheus' {@code histogram_quantile}, Atlas' {@code :percentiles}).
+     *
+     * @param enabled Determines whether percentile histograms should be published.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig publishPercentileHistogram(Boolean enabled) {
+        this.percentileHistogram = enabled;
+        return this;
+    }
+
+    /**
+     * Determines the number of digits of precision to maintain on the dynamic range histogram used to compute
+     * percentile approximations. The higher the degrees of precision, the more accurate the approximation is at the
+     * cost of more memory.
+     *
+     * @param digitsOfPrecision The digits of precision to maintain for percentile approximations.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig percentilePrecision(Integer digitsOfPrecision) {
+        this.percentilePrecision = digitsOfPrecision;
+        return this;
+    }
+
+    /**
+     * Sets the minimum value that this distribution summary is expected to observe. Sets a lower bound on histogram
+     * buckets that are shipped to monitoring systems that support aggregable percentile approximations.
+     *
+     * @param min The minimum value that this distribution summary is expected to observe.
+     * @return This builder.
+     */
+    public DistributionStatisticConfig minimumExpectedValue(Double min) {
+        this.minimumExpectedValue = min;
+        return this;
+    }
+
+    /**
+     * Sets the maximum value that this distribution summary is expected to observe. Sets an upper bound on histogram
+     * buckets that are shipped to monitoring systems that support aggregable percentile approximations.
+     *
+     * @param max The maximum value that this distribution summary is expected to observe.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig maximumExpectedValue(Double max) {
+        this.maximumExpectedValue = max;
+        return this;
+    }
+
+    /**
+     * Statistics emanating from a distribution summary like max, percentiles, and histogram counts decay over time to
+     * give greater weight to recent samples (exception: histogram counts are cumulative for those systems that expect
+     * cumulative histogram buckets). Samples are accumulated to such statistics in ring buffers which rotate after this
+     * expiry, with a buffer length of {@link #distributionStatisticBufferLength(Integer)}.
+     *
+     * @param expiryDuration The amount of time samples are accumulated to a histogram before it is reset and rotated.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig distributionStatisticExpiry(Duration expiryDuration) {
+        this.expiry = expiryDuration;
+        return this;
+    }
+
+    /**
+     * Statistics emanating from a distribution summary like max, percentiles, and histogram counts decay over time to
+     * give greater weight to recent samples (exception: histogram counts are cumulative for those systems that expect
+     * cumulative histogram buckets). Samples are accumulated to such statistics in ring buffers which rotate after
+     * {@link #distributionStatisticExpiry(Duration)}, with this buffer length.
+     *
+     * @param bufferLengthValue The number of histograms to keep in the ring buffer.
+     * @return DistributionStatisticConfig
+     */
+    public DistributionStatisticConfig distributionStatisticBufferLength(Integer bufferLengthValue) {
+        this.bufferLength = bufferLengthValue;
+        return this;
+    }
+}