[Test] Added test to verify that queue client reader updates batch size metrics

Author: andsel

logstash-core/src/main/java/org/logstash/ext/JrubyWrappedSynchronousQueueExt.java

@@ -23,7 +23,10 @@
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 
-import org.jruby.*;
+import org.jruby.Ruby;
+import org.jruby.RubyClass;
+import org.jruby.RubyNumeric;
+import org.jruby.RubyString;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
 import org.jruby.runtime.ThreadContext;

logstash-core/src/test/java/org/logstash/ext/JrubyMemoryReadClientExtTest.java

@@ -26,13 +26,19 @@
 import org.jruby.RubyHash;
 import org.jruby.runtime.ThreadContext;
 import org.junit.Test;
+import org.logstash.Event;
 import org.logstash.RubyTestBase;
+import org.logstash.RubyUtil;
 import org.logstash.execution.QueueBatch;
 import org.logstash.instrument.metrics.AbstractNamespacedMetricExt;
+import org.logstash.instrument.metrics.MetricKeys;
 import org.logstash.instrument.metrics.MockNamespacedMetric;
+import org.logstash.instrument.metrics.histogram.HistogramMetric;
+import org.logstash.instrument.metrics.histogram.HistogramSnapshot;
 
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.Assert.assertEquals;
 
 /**
  * Tests for {@link JrubyMemoryReadClientExt}.
@@ -58,4 +64,24 @@ public void testInflightBatchesTracking() throws InterruptedException, IOExcepti
         client.closeBatch(batch);
         assertThat(client.rubyGetInflightBatches(context).size(), is(0));
     }
+
+    @Test
+    public void givenNonEmptyQueueAndEnabledBatchSizeMetricThenHistogramContainsData() throws InterruptedException {
+        final JrubyEventExtLibrary.RubyEvent testEvent = JrubyEventExtLibrary.RubyEvent.newRubyEvent(RubyUtil.RUBY, new Event());
+        final BlockingQueue<JrubyEventExtLibrary.RubyEvent> queue = new ArrayBlockingQueue<>(10);
+        queue.add(testEvent);
+
+        final JrubyMemoryReadClientExt client = JrubyMemoryReadClientExt.create(queue, 5, 50);
+
+        AbstractNamespacedMetricExt metric = MockNamespacedMetric.create();
+        client.setPipelineMetric(metric);
+
+        final QueueBatch batch = client.readBatch();
+        assertEquals(1, batch.filteredSize());
+
+        HistogramMetric histogram = HistogramMetric.fromRubyBase(metric, MetricKeys.BATCH_SIZE_KEY);
+        HistogramSnapshot metricSnapshot = histogram.getValue();
+        assertEquals(1.0, metricSnapshot.get75Percentile(), 0.0001);
+        assertEquals(1.0, metricSnapshot.get90Percentile(), 0.0001);
+    }
 }