Fixed a bug of carrying default dimensions over flushes (#75)

* Fixed a bug of carrying default dimensions over flushes

Author: yaozhaoy

src/main/java/software/amazon/cloudwatchlogs/emf/model/Metadata.java

@@ -70,6 +70,11 @@ MetricDirective createMetricDirective() {
         return newMetricDirective;
     }
 
+    void setMetricDirective(MetricDirective metricDirective) {
+        cloudWatchMetrics = new ArrayList<>();
+        cloudWatchMetrics.add(metricDirective);
+    }
+
     /**
      * Test if there's any metric added.
      *

src/main/java/software/amazon/cloudwatchlogs/emf/model/MetricDirective.java

@@ -115,4 +115,18 @@ List<DimensionSet> getAllDimensions() {
     boolean hasNoMetrics() {
         return this.getMetrics().isEmpty();
     }
+
+    /**
+     * Create a copy of the metric directive without having the existing metrics
+     *
+     * @return A object of metric directive
+     */
+    MetricDirective copyWithoutMetrics() {
+        MetricDirective metricDirective = new MetricDirective();
+        metricDirective.setDefaultDimensions(this.defaultDimensions);
+        metricDirective.setDimensions(this.dimensions);
+        metricDirective.setNamespace(this.namespace);
+        metricDirective.shouldUseDefaultDimension = this.shouldUseDefaultDimension;
+        return metricDirective;
+    }
 }

src/main/java/software/amazon/cloudwatchlogs/emf/model/MetricsContext.java

@@ -37,6 +37,12 @@ public MetricsContext(RootNode rootNode) {
         metricDirective = rootNode.getAws().createMetricDirective();
     }
 
+    public MetricsContext(MetricDirective metricDirective) {
+        this();
+        this.rootNode.getAws().setMetricDirective(metricDirective);
+        this.metricDirective = metricDirective;
+    }
+
     public MetricsContext(
             String namespace,
             Map<String, Object> properties,
@@ -191,11 +197,7 @@ public void putMetadata(String key, Object value) {
 
     /** @return Creates an independently flushable context. */
     public MetricsContext createCopyWithContext() {
-        return new MetricsContext(
-                this.metricDirective.getNamespace(),
-                this.rootNode.getProperties(),
-                this.metricDirective.getDimensions(),
-                this.metricDirective.getDefaultDimensions());
+        return new MetricsContext(metricDirective.copyWithoutMetrics());
     }
 
     /**

src/test/java/software/amazon/cloudwatchlogs/emf/logger/MetricsLoggerTest.java

@@ -17,6 +17,7 @@
 package software.amazon.cloudwatchlogs.emf.logger;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.*;
 
@@ -201,6 +202,53 @@ public void testNoDefaultDimensionsAfterSetDimension() {
         expectDimension("Name", "Test");
     }
 
+    @Test
+    public void testFlushPreserveDimensions() {
+        MetricsLogger logger = new MetricsLogger(envProvider);
+        logger.setDimensions(DimensionSet.of("Name", "Test"));
+        logger.flush();
+        expectDimension("Name", "Test");
+
+        logger.flush();
+        expectDimension("Name", "Test");
+    }
+
+    @Test
+    public void testFlushDoesntPreserveMetrics() {
+        MetricsLogger logger = new MetricsLogger(envProvider);
+        logger.setDimensions(DimensionSet.of("Name", "Test"));
+        logger.putMetric("Count", 1.0);
+        logger.flush();
+        assertTrue(sink.getLogEvents().get(0).contains("Count"));
+
+        logger.flush();
+        assertFalse(sink.getLogEvents().get(0).contains("Count"));
+    }
+
+    @Test
+    public void testNoDimensionsAfterSetEmptyDimensionSet() {
+        MetricsLogger logger = new MetricsLogger(envProvider);
+
+        logger.setDimensions();
+        logger.flush();
+
+        List<DimensionSet> dimensions = sink.getContext().getDimensions();
+        assertEquals(0, dimensions.size());
+    }
+
+    @Test
+    public void testNoDimensionsAfterSetEmptyDimensionSetWithMultipleFlush() {
+        MetricsLogger logger = new MetricsLogger(envProvider);
+
+        logger.setDimensions();
+        logger.flush();
+
+        assertEquals(0, sink.getContext().getDimensions().size());
+
+        logger.flush();
+        assertEquals(0, sink.getContext().getDimensions().size());
+    }
+
     private void expectDimension(String dimension, String value) {
         List<DimensionSet> dimensions = sink.getContext().getDimensions();
         assertEquals(dimensions.size(), 1);