#2760 - Add ServerMetrics.asJson() ... to support conversion of collected metrics to json

ebean-api/src/main/java/io/ebean/meta/BasicMetricVisitor.java

@@ -37,6 +37,11 @@ public class BasicMetricVisitor extends AbstractMetricVisitor implements ServerM
     return name;
   }
 
+  @Override
+  public ServerMetricsAsJson asJson() {
+    return new MetricsAsJson(this);
+  }
+
   @Override
   public List<MetaTimedMetric> timedMetrics() {
     return timed;

ebean-api/src/main/java/io/ebean/meta/MetaInfoManager.java

@@ -16,17 +16,6 @@ public interface MetaInfoManager {
    */
   ServerMetrics collectMetrics();
 
-  /**
-   * Given the already collected metrics provide them in json form.
-   * <p>
-   * Expected to be used when we wish to collect the metrics and report them
-   * to some service and additionally format them as json for say output into
-   * an application log.
-   *
-   * @param metrics The already collected metrics
-   */
-  ServerMetricsAsJson metricsAsJson(ServerMetrics metrics);
-
   /**
    * Collect the metrics in raw JSON form.
    * <pre>{@code

ebean-api/src/main/java/io/ebean/meta/MetricsAsJson.java

@@ -0,0 +1,217 @@
+package io.ebean.meta;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.util.Comparator;
+import java.util.List;
+
+final class MetricsAsJson implements ServerMetricsAsJson {
+
+  private final ServerMetrics metrics;
+  private Appendable writer;
+  /**
+   * By default, include sql and location attributes for the initial collection only.
+   */
+  private int includeExtraAttributes = 1;
+  private boolean withHeader = true;
+  private boolean withHash = true;
+  private String newLine = "\n";
+  private Comparator<MetaTimedMetric> sortBy = SortMetric.NAME;
+  private int listCounter;
+  private int objKeyCounter;
+
+  MetricsAsJson(ServerMetrics metrics) {
+    this.metrics = metrics;
+  }
+
+  @Override
+  public ServerMetricsAsJson withHeader(boolean withHeader) {
+    this.withHeader = withHeader;
+    return this;
+  }
+
+  @Override
+  public ServerMetricsAsJson withExtraAttributes(boolean extraAttributes) {
+    this.includeExtraAttributes = extraAttributes ? 2 : 0;
+    return this;
+  }
+
+  @Override
+  public ServerMetricsAsJson withHash(boolean withHash) {
+    this.withHash = withHash;
+    return this;
+  }
+
+  @Override
+  public ServerMetricsAsJson withSort(Comparator<MetaTimedMetric> sortBy) {
+    this.sortBy = sortBy;
+    return this;
+  }
+
+  @Override
+  public ServerMetricsAsJson withNewLine(boolean withNewLine) {
+    this.newLine = withNewLine ? "\n" : "";
+    return this;
+  }
+
+  @Override
+  public String json() {
+    writer = new StringWriter();
+    collect();
+    return writer.toString();
+  }
+
+  @Override
+  public void write(Appendable buffer) {
+    writer = buffer;
+    collect();
+  }
+
+  private void collect() {
+    try {
+      start();
+      for (MetaTimedMetric metric : metrics.timedMetrics()) {
+        logTimed(metric);
+      }
+
+      List<MetaCountMetric> countMetrics = metrics.countMetrics();
+      if (!countMetrics.isEmpty()) {
+        if (sortBy != null) {
+          countMetrics.sort(SortMetric.COUNT_NAME);
+        }
+        for (MetaCountMetric metric : countMetrics) {
+          logCount(metric);
+        }
+      }
+
+      List<MetaQueryMetric> queryMetrics = metrics.queryMetrics();
+      if (!queryMetrics.isEmpty()) {
+        if (sortBy != null) {
+          queryMetrics.sort(sortBy);
+        }
+        for (MetaQueryMetric metric : queryMetrics) {
+          logQuery(metric);
+        }
+      }
+      end();
+    } catch (IOException e) {
+      throw new RuntimeException("Error writing metrics as JSON", e);
+    }
+  }
+
+  private void start() throws IOException {
+    if (withHeader) {
+      objStart();
+      key("db");
+      val(metrics.name());
+      key("metrics");
+      listStart();
+    }
+  }
+
+  private void end() throws IOException {
+    if (withHeader) {
+      listEnd();
+      objEnd();
+    }
+  }
+
+  private void objStart() throws IOException {
+    objKeyCounter = 0;
+    writer.append("{");
+  }
+
+  private void objEnd() throws IOException {
+    writer.append("}");
+  }
+
+  private void listStart() throws IOException {
+    listCounter = 0;
+    writer.append("[");
+    writer.append(newLine);
+  }
+
+  private void listEnd() throws IOException {
+    writer.append("]");
+  }
+
+  private void key(String key) throws IOException {
+    if (objKeyCounter++ > 0) {
+      writer.append(", ");
+    }
+    writer.append("\"").append(key).append("\":");
+  }
+
+  private void val(long count) throws IOException {
+    writer.append(Long.toString(count));
+  }
+
+  private void val(String val) throws IOException {
+    writer.append("\"").append(val).append("\"");
+  }
+
+  private void metricStart(MetaMetric metric) throws IOException {
+    if (listCounter++ > 0) {
+      writer.append(",").append(newLine);
+    }
+    objStart();
+    key("name");
+    val(metric.name());
+  }
+
+  private void metricEnd() throws IOException {
+    objEnd();
+  }
+
+  private void logCount(MetaCountMetric metric) throws IOException {
+    metricStart(metric);
+    key("count");
+    val(metric.count());
+    metricEnd();
+  }
+
+  private void logTimed(MetaTimedMetric metric) throws IOException {
+    metricStart(metric);
+    appendTiming(metric);
+    if (isIncludeDetail(metric)) {
+      append("loc", metric.location());
+    }
+    metricEnd();
+  }
+
+  private void logQuery(MetaQueryMetric metric) throws IOException {
+    metricStart(metric);
+    appendTiming(metric);
+    if (withHash) {
+      append("hash", metric.hash());
+    }
+    if (isIncludeDetail(metric)) {
+      append("loc", metric.location());
+      append("sql", metric.sql());
+    }
+    metricEnd();
+  }
+
+  private boolean isIncludeDetail(MetaTimedMetric metric) {
+    return includeExtraAttributes == 2 || includeExtraAttributes == 1 && metric.initialCollection();
+  }
+
+  private void append(String key, String val) throws IOException {
+    if (val != null) {
+      key(key);
+      val(val);
+    }
+  }
+
+  private void appendTiming(MetaTimedMetric timedMetric) throws IOException {
+    append("count", timedMetric.count());
+    append("total", timedMetric.total());
+    append("mean", timedMetric.mean());
+    append("max", timedMetric.max());
+  }
+
+  private void append(String key, long value) throws IOException {
+    key(key);
+    val(value);
+  }
+}

ebean-api/src/main/java/io/ebean/meta/ServerMetrics.java

@@ -12,6 +12,11 @@ public interface ServerMetrics {
    */
   String name();
 
+  /**
+   * Return ServerMetricsAsJson to build the metrics as JSON content.
+   */
+  ServerMetricsAsJson asJson();
+
   /**
    * Return timed metrics for Transactions, labelled SqlQuery, labelled SqlUpdate.
    */