Metrics - support both CUMULATIVE and DELTA metrics collection concur…

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

@@ -5,21 +5,31 @@
  */
 public abstract class AbstractMetricVisitor implements MetricVisitor {
 
-  private final boolean reset;
+  private final Mode mode;
   private final boolean collectTransactionMetrics;
   private final boolean collectQueryMetrics;
   private final boolean collectL2Metrics;
 
   public AbstractMetricVisitor(boolean reset, boolean collectTransactionMetrics, boolean collectQueryMetrics, boolean collectL2Metrics) {
-    this.reset = reset;
+    this(reset ? Mode.RESET : Mode.CUMULATIVE,
+      collectTransactionMetrics, collectQueryMetrics, collectL2Metrics);
+  }
+
+  public AbstractMetricVisitor(Mode mode, boolean collectTransactionMetrics, boolean collectQueryMetrics, boolean collectL2Metrics) {
+    this.mode = mode;
     this.collectTransactionMetrics = collectTransactionMetrics;
     this.collectQueryMetrics = collectQueryMetrics;
     this.collectL2Metrics = collectL2Metrics;
   }
 
   @Override
   public boolean reset() {
-    return reset;
+    return mode == Mode.RESET;
+  }
+
+  @Override
+  public Mode mode() {
+    return mode;
   }
 
   @Override
@@ -47,4 +57,3 @@ public void visitEnd() {
     // do nothing by default
   }
 }
-

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

@@ -30,7 +30,16 @@ public BasicMetricVisitor(String name, Function<String,String> naming) {
    * Construct specifying reset and what to collect.
    */
   public BasicMetricVisitor(String name, Function<String,String> naming, boolean reset, boolean collectTransactionMetrics, boolean collectQueryMetrics, boolean collectL2Metrics) {
-    super(reset, collectTransactionMetrics, collectQueryMetrics, collectL2Metrics);
+    this(name, naming, reset ? Mode.RESET : Mode.CUMULATIVE,
+      collectTransactionMetrics, collectQueryMetrics, collectL2Metrics);
+  }
+
+  /**
+   * Construct specifying the collection mode and what to collect.
+   */
+  public BasicMetricVisitor(String name, Function<String,String> naming, Mode mode,
+                            boolean collectTransactionMetrics, boolean collectQueryMetrics, boolean collectL2Metrics) {
+    super(mode, collectTransactionMetrics, collectQueryMetrics, collectL2Metrics);
     this.name = name;
     this.naming = naming;
   }

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

@@ -7,6 +7,12 @@
  */
 public interface MetricVisitor {
 
+  enum Mode {
+    RESET,
+    CUMULATIVE,
+    DELTA
+  }
+
   /**
    * Return the naming convention that should be applied to the reported metric names.
    */
@@ -17,6 +23,13 @@ public interface MetricVisitor {
    */
   boolean reset();
 
+  /**
+   * Return the metric collection mode.
+   */
+  default Mode mode() {
+    return reset() ? Mode.RESET : Mode.CUMULATIVE;
+  }
+
   /**
    * Return true if we should visit the transaction metrics.
    */

ebean-api/src/main/java/io/ebean/metric/TimedMetric.java

@@ -37,6 +37,16 @@ public interface TimedMetric {
    */
   TimedMetricStats collect(boolean reset);
 
+  /**
+   * Collect a snapshot using the given collection mode.
+   *
+   * <p>Implementations that do not support delta collection use cumulative
+   * collection for {@link MetricVisitor.Mode#DELTA}.</p>
+   */
+  default TimedMetricStats collect(MetricVisitor.Mode mode) {
+    return collect(mode == MetricVisitor.Mode.RESET);
+  }
+
   /**
    * Visit non empty metrics.
    */

ebean-api/src/test/java/io/ebean/meta/MetaInfoManagerTest.java

@@ -43,4 +43,18 @@ public List<MetaQueryPlan> queryPlanCollectNow(QueryPlanRequest request) {
 
     assertThat(manager.collectMetrics(false)).isSameAs(metrics);
   }
+
+  @Test
+  void basicMetricVisitorSupportsExplicitCollectionModes() {
+    var reset = new BasicMetricVisitor("db", MetricNamingMatch.INSTANCE, MetricVisitor.Mode.RESET, true, true, true);
+    var cumulative = new BasicMetricVisitor("db", MetricNamingMatch.INSTANCE, MetricVisitor.Mode.CUMULATIVE, true, true, true);
+    var delta = new BasicMetricVisitor("db", MetricNamingMatch.INSTANCE, MetricVisitor.Mode.DELTA, true, true, true);
+
+    assertThat(reset.reset()).isTrue();
+    assertThat(reset.mode()).isEqualTo(MetricVisitor.Mode.RESET);
+    assertThat(cumulative.reset()).isFalse();
+    assertThat(cumulative.mode()).isEqualTo(MetricVisitor.Mode.CUMULATIVE);
+    assertThat(delta.reset()).isFalse();
+    assertThat(delta.mode()).isEqualTo(MetricVisitor.Mode.DELTA);
+  }
 }

ebean-core/src/main/java/io/ebeaninternal/server/profile/DCountMetric.java

@@ -4,37 +4,32 @@
 import io.ebean.metric.CountMetric;
 import io.ebean.metric.CountMetricStats;
 
-import java.util.concurrent.atomic.LongAdder;
-
 /**
  * Used to collect counter metrics.
  */
 final class DCountMetric implements CountMetric {
 
   private final String name;
-  private final LongAdder count = new LongAdder();
+  private final ValueAdder count = new ValueAdder();
   private String reportName;
 
   DCountMetric(String name) {
     this.name = name;
   }
 
-  /**
-   * Add a value. Usually the value is Time or Bytes etc.
-   */
   @Override
   public void add(long value) {
     count.add(value);
   }
 
   @Override
   public void increment() {
-    count.increment();
+    count.add(1);
   }
 
   @Override
   public boolean isEmpty() {
-    return count.sum() == 0;
+    return count.currentValue() == 0;
   }
 
   @Override
@@ -44,12 +39,25 @@ public void reset() {
 
   @Override
   public long get(boolean reset) {
-    return reset ? count.sumThenReset() : count.sum();
+    return reset ? count.getAndReset() : count.cumulative();
   }
 
   @Override
   public void visit(MetricVisitor visitor) {
-    long val = visitor.reset() ? count.sumThenReset() : count.sum();
+    long val;
+    switch (visitor.mode()) {
+      case RESET:
+        val = count.getAndReset();
+        break;
+      case CUMULATIVE:
+        val = count.cumulative();
+        break;
+      case DELTA:
+        val = count.delta();
+        break;
+      default:
+        throw new IllegalStateException("Unknown metric collection mode");
+    }
     if (val > 0) {
       final String name = reportName != null ? reportName : reportName(visitor);
       visitor.visitCount(new DCountMetricStats(name, val));

ebean-core/src/main/java/io/ebeaninternal/server/profile/DQueryPlanMetric.java

@@ -20,7 +20,7 @@ final class DQueryPlanMetric implements QueryPlanMetric {
 
   @Override
   public void visit(MetricVisitor visitor) {
-    TimedMetricStats stats = metric.collect(visitor.reset());
+    TimedMetricStats stats = metric.collect(visitor.mode());
     if (stats != null) {
       String name = reportName != null ? reportName : reportName(visitor);
       visitor.visitQuery(new Stats(name, meta, stats, collected));

ebean-core/src/main/java/io/ebeaninternal/server/profile/DTimedMetric.java

@@ -4,7 +4,6 @@
 import io.ebean.metric.TimedMetric;
 
 import java.util.concurrent.atomic.LongAccumulator;
-import java.util.concurrent.atomic.LongAdder;
 
 /**
  * Used to collect timed execution statistics.
@@ -15,8 +14,8 @@
 final class DTimedMetric implements TimedMetric {
 
   private final String name;
-  private final LongAdder count = new LongAdder();
-  private final LongAdder total = new LongAdder();
+  private final ValueAdder count = new ValueAdder();
+  private final ValueAdder total = new ValueAdder();
   private final LongAccumulator max = new LongAccumulator(Math::max, 0);
   private boolean collected;
   private String reportName;
@@ -43,14 +42,14 @@ public void addSinceNanos(long startNanos) {
 
   @Override
   public void add(long value) {
-    count.increment();
+    count.add(1);
     total.add(value);
     max.accumulate(value);
   }
 
   @Override
   public boolean isEmpty() {
-    return count.sum() == 0;
+    return count.currentValue() == 0;
   }
 
   @Override
@@ -62,29 +61,61 @@ public void reset() {
 
   @Override
   public void visit(MetricVisitor visitor) {
-    final long countSum = visitor.reset() ? count.sumThenReset() : count.sum();
-    if (countSum > 0) {
+    final DTimeMetricStats stats = collect(visitor.mode());
+    if (stats != null) {
       final String name = reportName != null ? reportName : reportName(visitor);
-      visitor.visitTimed(stats(visitor.reset(), name, countSum));
+      stats.setName(name);
+      visitor.visitTimed(stats);
     }
   }
 
   @Override
   public DTimeMetricStats collect(boolean reset) {
-    final long countSum = reset ? count.sumThenReset() : count.sum();
+    return collect(reset ? MetricVisitor.Mode.RESET : MetricVisitor.Mode.CUMULATIVE);
+  }
+
+  @Override
+  public DTimeMetricStats collect(MetricVisitor.Mode mode) {
+    final long countSum;
+    switch (mode) {
+      case RESET:
+        countSum = count.getAndReset();
+        break;
+      case CUMULATIVE:
+        countSum = count.cumulative();
+        break;
+      case DELTA:
+        countSum = count.delta();
+        break;
+      default:
+        throw new IllegalStateException("Unknown metric collection mode");
+    }
     if (countSum == 0) {
       return null;
     } else {
-      return stats(reset, name, countSum);
+      return stats(mode, name, countSum);
     }
   }
 
   /**
    * Return the current statistics resetting the internal values if reset is true.
    */
-  private DTimeMetricStats stats(boolean reset, String name, long countSum) {
+  private DTimeMetricStats stats(MetricVisitor.Mode mode, String name, long countSum) {
     try {
-      final long totalSum = reset ? total.sumThenReset() : total.sum();
+      final long totalSum;
+      switch (mode) {
+        case RESET:
+          totalSum = total.getAndReset();
+          break;
+        case CUMULATIVE:
+          totalSum = total.cumulative();
+          break;
+        case DELTA:
+          totalSum = total.delta();
+          break;
+        default:
+          throw new IllegalStateException("Unknown metric collection mode");
+      }
       return new DTimeMetricStats(name, collected, countSum, totalSum, max.getThenReset());
     } finally {
       collected = true;

ebean-core/src/main/java/io/ebeaninternal/server/profile/DTimedProfileLocation.java

@@ -46,7 +46,7 @@ public void add(long executionTime) {
 
   @Override
   public void visit(MetricVisitor visitor) {
-    TimedMetricStats collect = timedMetric.collect(visitor.reset());
+    TimedMetricStats collect = timedMetric.collect(visitor.mode());
     if (collect != null) {
       final String name = reportName != null ? reportName : reportName(visitor, collect.name());
       collect.setName(name);

ebean-core/src/main/java/io/ebeaninternal/server/profile/ValueAdder.java

@@ -0,0 +1,42 @@
+package io.ebeaninternal.server.profile;
+
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.LongAdder;
+
+/**
+ * Accumulates a value while supporting cumulative and reset-based delta reads.
+ */
+final class ValueAdder {
+
+  private final LongAdder value = new LongAdder();
+  private final AtomicLong previousValue = new AtomicLong();
+
+  void add(long amount) {
+    value.add(amount);
+  }
+
+  long cumulative() {
+    return value.sum();
+  }
+
+  long delta() {
+    long currentValue = value.sum();
+    long previous = previousValue.getAndSet(currentValue);
+    return currentValue >= previous ? currentValue - previous : currentValue;
+  }
+
+  long getAndReset() {
+    long currentValue = value.sumThenReset();
+    previousValue.set(0);
+    return currentValue;
+  }
+
+  void reset() {
+    value.reset();
+    previousValue.set(0);
+  }
+
+  long currentValue() {
+    return value.sum();
+  }
+}