Merge pull request #71 from gpolaert/operation-name

Override the operation name

dd-java-agent/src/main/java/com/datadoghq/trace/agent/integration/MongoHelper.java

@@ -5,6 +5,7 @@ import com.mongodb.MongoClientOptions;
 import com.mongodb.event.CommandStartedEvent;
 import io.opentracing.Span;
 import io.opentracing.contrib.mongo.TracingCommandListener;
+import io.opentracing.tag.Tags;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
@@ -50,8 +51,14 @@ public class MongoHelper extends DDAgentTracingHelper<MongoClientOptions.Builder
 
   public void decorate(final Span span, final CommandStartedEvent event) {
     try {
+      // normalize the Mongo command so that parameters are removed from the string
       final BsonDocument normalized = norm(event.getCommand());
-      span.setTag(DDTags.RESOURCE_NAME, normalized.toString());
+      final String mongoCmd = normalized.toString();
+
+      // add specific resource name and replace the `db.statement` OpenTracing
+      // tag with the quantized version of the Mongo command
+      span.setTag(DDTags.RESOURCE_NAME, mongoCmd);
+      span.setTag(Tags.DB_STATEMENT.getKey(), mongoCmd);
     } catch (final Throwable e) {
       log.warn("Couldn't decorate the mongo query: " + e.getMessage(), e);
     }

dd-trace/src/main/java/com/datadoghq/trace/DDSpanContext.java

@@ -1,6 +1,6 @@
 package com.datadoghq.trace;
 
-import com.datadoghq.trace.integration.DDSpanContextDecorator;
+import com.datadoghq.trace.integration.AbstractDecorator;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.google.common.collect.Maps;
 import io.opentracing.tag.Tags;
@@ -28,28 +28,27 @@ public class DDSpanContext implements io.opentracing.SpanContext {
   private final long parentId;
   private final String threadName = Thread.currentThread().getName();
   private final long threadId = Thread.currentThread().getId();
-  private Map<String, String> baggageItems;
+  /** The collection of all span related to this one */
+  private final Queue<DDBaseSpan<?>> trace;
 
   // DD attributes
+  /** For technical reasons, the ref to the original tracer */
+  private final DDTracer tracer;
+
+  private Map<String, String> baggageItems;
   /** The service name is required, otherwise the span are dropped by the agent */
   private String serviceName;
   /** The resource associated to the service (server_web, database, etc.) */
   private String resourceName;
   /** True indicates that the span reports an error */
   private boolean errorFlag;
-
   /** The type of the span. If null, the Datadog Agent will report as a custom */
   private String spanType;
-  /** The collection of all span related to this one */
-  private final Queue<DDBaseSpan<?>> trace;
   /** Each span have an operation name describing the current span */
   private String operationName;
-
+  // Others attributes
   /** Tags are associated to the current span, they will not propagate to the children span */
   private Map<String, Object> tags;
-  // Others attributes
-  /** For technical reasons, the ref to the original tracer */
-  private final DDTracer tracer;
 
   public DDSpanContext(
       final long traceId,
@@ -109,12 +108,20 @@ public class DDSpanContext implements io.opentracing.SpanContext {
     return serviceName;
   }
 
+  public void setServiceName(final String serviceName) {
+    this.serviceName = serviceName;
+  }
+
   public String getResourceName() {
     return this.resourceName == null || this.resourceName.isEmpty()
         ? this.operationName
         : this.resourceName;
   }
 
+  public void setResourceName(final String resourceName) {
+    this.resourceName = resourceName;
+  }
+
   public boolean getErrorFlag() {
     return errorFlag;
   }
@@ -127,6 +134,10 @@ public class DDSpanContext implements io.opentracing.SpanContext {
     return spanType;
   }
 
+  public void setSpanType(final String spanType) {
+    this.spanType = spanType;
+  }
+
   public void setBaggageItem(final String key, final String value) {
     if (this.baggageItems.isEmpty()) {
       this.baggageItems = new HashMap<String, String>();
@@ -184,9 +195,9 @@ public class DDSpanContext implements io.opentracing.SpanContext {
     this.tags.put(tag, value);
 
     //Call decorators
-    final List<DDSpanContextDecorator> decorators = tracer.getSpanContextDecorators(tag);
+    final List<AbstractDecorator> decorators = tracer.getSpanContextDecorators(tag);
     if (decorators != null) {
-      for (final DDSpanContextDecorator decorator : decorators) {
+      for (final AbstractDecorator decorator : decorators) {
         decorator.afterSetTag(this, tag, value);
       }
     }
@@ -223,23 +234,11 @@ public class DDSpanContext implements io.opentracing.SpanContext {
         .toString();
   }
 
-  public void setOperationName(final String operationName) {
-    this.operationName = operationName;
-  }
-
   public String getOperationName() {
     return operationName;
   }
 
-  public void setServiceName(final String serviceName) {
-    this.serviceName = serviceName;
-  }
-
-  public void setResourceName(final String resourceName) {
-    this.resourceName = resourceName;
-  }
-
-  public void setSpanType(final String spanType) {
-    this.spanType = spanType;
+  public void setOperationName(final String operationName) {
+    this.operationName = operationName;
   }
 }

dd-trace/src/main/java/com/datadoghq/trace/DDTracer.java

@@ -1,6 +1,6 @@
 package com.datadoghq.trace;
 
-import com.datadoghq.trace.integration.DDSpanContextDecorator;
+import com.datadoghq.trace.integration.AbstractDecorator;
 import com.datadoghq.trace.propagation.Codec;
 import com.datadoghq.trace.propagation.HTTPCodec;
 import com.datadoghq.trace.sampling.AllSampler;
@@ -39,7 +39,7 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
   private final String defaultServiceName;
 
   /** Span context decorators */
-  private final Map<String, List<DDSpanContextDecorator>> spanContextDecorators = new HashMap<>();
+  private final Map<String, List<AbstractDecorator>> spanContextDecorators = new HashMap<>();
 
   private final CodecRegistry registry;
 
@@ -70,18 +70,18 @@ public class DDTracer extends ThreadLocalActiveSpanSource implements io.opentrac
    *
    * @return the list of span context decorators
    */
-  public List<DDSpanContextDecorator> getSpanContextDecorators(final String tag) {
+  public List<AbstractDecorator> getSpanContextDecorators(final String tag) {
     return spanContextDecorators.get(tag);
   }
 
   /**
-   * Add a new decorator in the list ({@link DDSpanContextDecorator})
+   * Add a new decorator in the list ({@link AbstractDecorator})
    *
    * @param decorator The decorator in the list
    */
-  public void addDecorator(final DDSpanContextDecorator decorator) {
+  public void addDecorator(final AbstractDecorator decorator) {
 
-    List<DDSpanContextDecorator> list = spanContextDecorators.get(decorator.getMatchingTag());
+    List<AbstractDecorator> list = spanContextDecorators.get(decorator.getMatchingTag());
     if (list == null) {
       list = new ArrayList<>();
     }

dd-trace/src/main/java/com/datadoghq/trace/integration/AbstractDecorator.java

@@ -7,7 +7,7 @@ import com.datadoghq.trace.DDTags;
  * Span decorators are called when new tags are written and proceed to various remappings and
  * enrichments
  */
-public abstract class DDSpanContextDecorator {
+public abstract class AbstractDecorator {
 
   private String matchingTag;
 
@@ -17,10 +17,10 @@ public abstract class DDSpanContextDecorator {
 
   private String setValue;
 
-  public boolean afterSetTag(DDSpanContext context, String tag, Object value) {
+  public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
     if ((this.getMatchingValue() == null || value.equals(this.getMatchingValue()))) {
-      String targetTag = getSetTag() == null ? tag : getSetTag();
-      String targetValue = getSetValue() == null ? String.valueOf(value) : getSetValue();
+      final String targetTag = getSetTag() == null ? tag : getSetTag();
+      final String targetValue = getSetValue() == null ? String.valueOf(value) : getSetValue();
 
       if (targetTag.equals(DDTags.SERVICE_NAME)) {
         context.setServiceName(targetValue);
@@ -41,7 +41,7 @@ public abstract class DDSpanContextDecorator {
     return matchingTag;
   }
 
-  public void setMatchingTag(String tag) {
+  public void setMatchingTag(final String tag) {
     this.matchingTag = tag;
   }
 
@@ -49,7 +49,7 @@ public abstract class DDSpanContextDecorator {
     return matchingValue;
   }
 
-  public void setMatchingValue(String value) {
+  public void setMatchingValue(final String value) {
     this.matchingValue = value;
   }
 
@@ -57,7 +57,7 @@ public abstract class DDSpanContextDecorator {
     return setTag;
   }
 
-  public void setSetTag(String targetTag) {
+  public void setSetTag(final String targetTag) {
     this.setTag = targetTag;
   }
 
@@ -65,7 +65,7 @@ public abstract class DDSpanContextDecorator {
     return setValue;
   }
 
-  public void setSetValue(String targetValue) {
+  public void setSetValue(final String targetValue) {
     this.setValue = targetValue;
   }
 }

dd-trace/src/main/java/com/datadoghq/trace/integration/DBStatementAsResourceName.java

@@ -3,42 +3,11 @@ package com.datadoghq.trace.integration;
 import com.datadoghq.trace.DDTags;
 import io.opentracing.tag.Tags;
 
-public class DBStatementAsResourceName extends DDSpanContextDecorator {
+public class DBStatementAsResourceName extends AbstractDecorator {
 
   public DBStatementAsResourceName() {
     super();
     this.setMatchingTag(Tags.DB_STATEMENT.getKey());
     this.setSetTag(DDTags.RESOURCE_NAME);
   }
-
-  //{ "insert" : "calls", "ordered" : true, "documents" : [{ "_id" : { "$oid" : "5979bbb0ed6fed5749cc9e7c" }, "name" : "MongoDB", "type" : "database", "identifier" : "10", "versions" : ["v3.2", "v3.0", "v2.6"], "info" : { "x" : 203, "y" : 102 } }] }
-  private void normalizeFilter(final Object f) {}
 }
-
-  /*
-  def normalize_filter(f=None):
-      if f is None:
-          return {}
-      elif isinstance(f, list):
-          # normalize lists of filters
-          # e.g. {$or: [ { age: { $lt: 30 } }, { type: 1 } ]}
-          return [normalize_filter(s) for s in f]
-      elif isinstance(f, dict):
-          # normalize dicts of filters
-          #   {$or: [ { age: { $lt: 30 } }, { type: 1 } ]})
-          out = {}
-          for k, v in iteritems(f):
-              if k == "$in" or k == "$nin":
-                  # special case $in queries so we don't loop over lists.
-                  out[k] = "?"
-              elif isinstance(v, list) or isinstance(v, dict):
-                  # RECURSION ALERT: needs to move to the agent
-                  out[k] = normalize_filter(v)
-              else:
-                  # NOTE: this shouldn't happen, but let's have a safeguard.
-                  out[k] = '?'
-          return out
-      else:
-          # FIXME[matt] unexpected type. not sure this should ever happen, but at
-          # least it won't crash.
-          return {}*/

dd-trace/src/main/java/com/datadoghq/trace/integration/DBTypeDecorator.java

@@ -8,9 +8,9 @@ import io.opentracing.tag.Tags;
  * This span decorator leverages DB tags. It allows the dev to define a custom service name and
  * retrieves some DB meta such as the statement
  */
-public class DBComponent extends DDSpanContextDecorator {
+public class DBTypeDecorator extends AbstractDecorator {
 
-  public DBComponent() {
+  public DBTypeDecorator() {
     super();
     this.setMatchingTag(Tags.DB_TYPE.getKey());
     this.setSetTag(DDTags.SERVICE_NAME);
@@ -22,6 +22,8 @@ public class DBComponent extends DDSpanContextDecorator {
     if (super.afterSetTag(context, tag, value)) {
       //Assign span type to DB
       context.setSpanType("db");
+      // Works for: mongo, cassandra, jdbc
+      context.setOperationName(String.valueOf(value) + ".query");
       return true;
     }
     return false;

dd-trace/src/main/java/com/datadoghq/trace/integration/ErrorFlag.java

@@ -3,18 +3,18 @@ package com.datadoghq.trace.integration;
 import com.datadoghq.trace.DDSpanContext;
 import io.opentracing.tag.Tags;
 
-public class ErrorFlag extends DDSpanContextDecorator {
+public class ErrorFlag extends AbstractDecorator {
   public ErrorFlag() {
     super();
     this.setMatchingTag(Tags.ERROR.getKey());
   }
 
   @Override
-  public boolean afterSetTag(DDSpanContext context, String tag, Object value) {
+  public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
     //Assign resource name
     try {
       context.setErrorFlag(Boolean.parseBoolean(String.valueOf(value)));
-    } catch (Throwable t) {
+    } catch (final Throwable t) {
       //DO NOTHING
     }
     return true;

dd-trace/src/main/java/com/datadoghq/trace/integration/HTTPComponent.java

@@ -8,7 +8,7 @@ import io.opentracing.tag.Tags;
  * This span decorator leverages HTTP tags. It allows the dev to define a custom service name and
  * retrieves some HTTP meta such as the request path
  */
-public class HTTPComponent extends DDSpanContextDecorator {
+public class HTTPComponent extends AbstractDecorator {
 
   public HTTPComponent() {
     super();
@@ -17,7 +17,7 @@ public class HTTPComponent extends DDSpanContextDecorator {
   }
 
   @Override
-  public boolean afterSetTag(DDSpanContext context, String tag, Object value) {
+  public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
     //Assign service name
     if (super.afterSetTag(context, tag, value)) {
       //Assign span type to WEB

dd-trace/src/main/java/com/datadoghq/trace/integration/OperationDecorator.java

@@ -0,0 +1,43 @@
+package com.datadoghq.trace.integration;
+
+import com.datadoghq.trace.DDSpanContext;
+import io.opentracing.tag.Tags;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * This span decorator is a simple mapping to override the operation DB tags. The operation name of
+ * DB integration are handled by the DBTypeDecorator
+ */
+public class OperationDecorator extends AbstractDecorator {
+
+  static final Map<String, String> MAPPINGS =
+      new HashMap<String, String>() {
+        {
+          // Component name <> Operation name
+          put("apache-httpclient", "apache.http");
+          put("java-aws-sdk", "aws.http");
+          // Jetty + Tomcat (same integration used)
+          put("java-web-servlet", "servlet.request");
+          // FIXME: JMS ops card is low (jms-send or jms-receive), may be this mapping is useless
+          put("java-jms", "jms");
+          put("okhttp", "okhttp.http");
+          // Cassandra, Mongo, JDBC are set via DBTypeDecorator
+        }
+      };
+
+  public OperationDecorator() {
+    super();
+    this.setMatchingTag(Tags.COMPONENT.getKey());
+  }
+
+  @Override
+  public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
+
+    if (MAPPINGS.containsKey(String.valueOf(value))) {
+      context.setOperationName(MAPPINGS.get(String.valueOf(value)));
+      return true;
+    }
+    return false;
+  }
+}

dd-trace/src/main/java/com/datadoghq/trace/integration/URLAsResourceName.java

@@ -5,7 +5,7 @@ import com.datadoghq.trace.DDTags;
 import io.opentracing.tag.Tags;
 import java.net.MalformedURLException;
 
-public class URLAsResourceName extends DDSpanContextDecorator {
+public class URLAsResourceName extends AbstractDecorator {
 
   public URLAsResourceName() {
     super();
@@ -14,12 +14,12 @@ public class URLAsResourceName extends DDSpanContextDecorator {
   }
 
   @Override
-  public boolean afterSetTag(DDSpanContext context, String tag, Object value) {
+  public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
     //Assign resource name
     try {
-      String path = new java.net.URL(String.valueOf(value)).getPath();
+      final String path = new java.net.URL(String.valueOf(value)).getPath();
       context.setResourceName(path);
-    } catch (MalformedURLException e) {
+    } catch (final MalformedURLException e) {
       context.setResourceName(String.valueOf(value));
     }
     return true;

dd-trace/src/main/java/com/datadoghq/trace/resolver/DDDecoratorsFactory.java

@@ -1,6 +1,6 @@
 package com.datadoghq.trace.resolver;
 
-import com.datadoghq.trace.integration.DDSpanContextDecorator;
+import com.datadoghq.trace.integration.AbstractDecorator;
 import java.util.ArrayList;
 import java.util.List;
 import lombok.extern.slf4j.Slf4j;
@@ -9,9 +9,8 @@ import lombok.extern.slf4j.Slf4j;
 @Slf4j
 public class DDDecoratorsFactory {
 
-  public static String DECORATORS_PACKAGE = "com.datadoghq.trace.integration.";
-
   public static final String CONFIG_PATH = "dd-trace-decorators";
+  public static String DECORATORS_PACKAGE = "com.datadoghq.trace.integration.";
 
   /**
    * Create decorators from configuration
@@ -19,9 +18,8 @@ public class DDDecoratorsFactory {
    * @param decoratorsConfig
    * @return the list of instanciated and configured decorators
    */
-  public static List<DDSpanContextDecorator> create(
-      final List<DDSpanDecoratorConfig> decoratorsConfig) {
-    final List<DDSpanContextDecorator> decorators = new ArrayList<>();
+  public static List<AbstractDecorator> create(final List<DDSpanDecoratorConfig> decoratorsConfig) {
+    final List<AbstractDecorator> decorators = new ArrayList<>();
     for (final DDSpanDecoratorConfig decoratorConfig : decoratorsConfig) {
       if (decoratorConfig.getType() == null) {
         log.warn("Cannot create decorator without type from configuration {}", decoratorConfig);
@@ -39,9 +37,9 @@ public class DDDecoratorsFactory {
         continue;
       }
 
-      DDSpanContextDecorator decorator = null;
+      AbstractDecorator decorator = null;
       try {
-        decorator = (DDSpanContextDecorator) decoratorClass.getConstructor().newInstance();
+        decorator = (AbstractDecorator) decoratorClass.getConstructor().newInstance();
       } catch (final Exception e) {
         log.warn(
             "Cannot create decorator as we could not invoke the default constructor. Provided configuration {}",
@@ -68,8 +66,8 @@ public class DDDecoratorsFactory {
     return decorators;
   }
 
-  public static List<DDSpanContextDecorator> createFromResources() {
-    List<DDSpanContextDecorator> result = new ArrayList<>();
+  public static List<AbstractDecorator> createFromResources() {
+    List<AbstractDecorator> result = new ArrayList<>();
     final TracerConfig config =
         FactoryUtils.loadConfigFromResource(CONFIG_PATH, TracerConfig.class);
     if (config != null) {

dd-trace/src/main/java/com/datadoghq/trace/resolver/DDTracerFactory.java

@@ -1,7 +1,7 @@
 package com.datadoghq.trace.resolver;
 
 import com.datadoghq.trace.DDTracer;
-import com.datadoghq.trace.integration.DDSpanContextDecorator;
+import com.datadoghq.trace.integration.AbstractDecorator;
 import com.datadoghq.trace.sampling.AbstractSampler;
 import com.datadoghq.trace.sampling.AllSampler;
 import com.datadoghq.trace.sampling.RateSampler;
@@ -102,8 +102,8 @@ public class DDTracerFactory {
     }
 
     //Create decorators from resource files
-    final List<DDSpanContextDecorator> decorators = DDDecoratorsFactory.createFromResources();
-    for (final DDSpanContextDecorator decorator : decorators) {
+    final List<AbstractDecorator> decorators = DDDecoratorsFactory.createFromResources();
+    for (final AbstractDecorator decorator : decorators) {
       tracer.addDecorator(decorator);
     }
 

dd-trace/src/main/resources/dd-trace-decorators.yaml

@@ -4,9 +4,9 @@ decorators:
   - type: HTTPComponent
     matchingValue: java-okhttp
     setValue: http-client
-  - type: DBComponent
   - type: HTTPComponent
     matchingValue: java-aws-sdk
     setValue: aws-client
-#  - type: DBStatementAsResourceName
   - type: ErrorFlag
+  - type: DBTypeDecorator
+  - type: OperationDecorator

dd-trace/src/test/groovy/com/datadoghq/trace/integration/SpanDecoratorTest.groovy

@@ -4,6 +4,7 @@ import com.datadoghq.trace.DDSpanContext
 import com.datadoghq.trace.DDTracer
 import com.datadoghq.trace.SpanFactory
 import io.opentracing.tag.StringTag
+import io.opentracing.tag.Tags
 import spock.lang.Specification
 
 class SpanDecoratorTest extends Specification {
@@ -11,7 +12,7 @@ class SpanDecoratorTest extends Specification {
   def "adding span personalisation using Decorators"() {
     setup:
     def tracer = new DDTracer()
-    def decorator = new DDSpanContextDecorator() {
+    def decorator = new AbstractDecorator() {
 
       @Override
       boolean afterSetTag(DDSpanContext context, String tag, Object value) {
@@ -32,4 +33,44 @@ class SpanDecoratorTest extends Specification {
     span.getTags().containsKey("newFoo")
     span.getTags().get("newFoo") == "newBar"
   }
+
+  def "override operation with OperationDecorator"() {
+
+    setup:
+    def tracer = new DDTracer()
+    def span = SpanFactory.newSpanOf(tracer)
+    tracer.addDecorator(new OperationDecorator())
+
+    when:
+    Tags.COMPONENT.set(span, component)
+
+    then:
+    span.getOperationName() == operationName
+
+    where:
+    component << OperationDecorator.MAPPINGS.keySet()
+    operationName << OperationDecorator.MAPPINGS.values()
+
+
+  }
+
+  def "override operation with DBTypeDecorator"() {
+
+    setup:
+    def tracer = new DDTracer()
+    def span = SpanFactory.newSpanOf(tracer)
+    tracer.addDecorator(new DBTypeDecorator())
+
+    when:
+    Tags.DB_TYPE.set(span, type)
+
+    then:
+    span.getOperationName() == type + ".query"
+    span.context().getSpanType() == "db"
+
+    where:
+    type = "foo"
+
+
+  }
 }

dd-trace/src/test/java/com/datadoghq/trace/resolver/TracerResolverTest.java

@@ -3,7 +3,7 @@ package com.datadoghq.trace.resolver;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.datadoghq.trace.DDTracer;
-import com.datadoghq.trace.integration.DDSpanContextDecorator;
+import com.datadoghq.trace.integration.AbstractDecorator;
 import com.datadoghq.trace.integration.HTTPComponent;
 import com.datadoghq.trace.integration.URLAsResourceName;
 import io.opentracing.NoopTracerFactory;
@@ -19,17 +19,16 @@ public class TracerResolverTest {
 
   @Test
   public void testResolve() {
-    DDTracerResolver tracerResolver = new DDTracerResolver();
-    DDTracer tracer = (DDTracer) tracerResolver.resolve();
+    final DDTracerResolver tracerResolver = new DDTracerResolver();
+    final DDTracer tracer = (DDTracer) tracerResolver.resolve();
 
     // for HTTP decorators
-    List<DDSpanContextDecorator> decorators =
-        tracer.getSpanContextDecorators(Tags.COMPONENT.getKey());
+    List<AbstractDecorator> decorators = tracer.getSpanContextDecorators(Tags.COMPONENT.getKey());
 
     assertThat(decorators.size()).isEqualTo(2);
-    DDSpanContextDecorator decorator = decorators.get(0);
+    AbstractDecorator decorator = decorators.get(0);
     assertThat(decorator.getClass()).isEqualTo(HTTPComponent.class);
-    HTTPComponent httpServiceDecorator = (HTTPComponent) decorator;
+    final HTTPComponent httpServiceDecorator = (HTTPComponent) decorator;
     assertThat(httpServiceDecorator.getMatchingTag()).isEqualTo("component");
     assertThat(httpServiceDecorator.getMatchingValue()).isEqualTo("hello");
     assertThat(httpServiceDecorator.getSetValue()).isEqualTo("world");
@@ -44,13 +43,13 @@ public class TracerResolverTest {
 
   @Test
   public void testResolveTracer() throws Exception {
-    Field tracerField = GlobalTracer.class.getDeclaredField("tracer");
+    final Field tracerField = GlobalTracer.class.getDeclaredField("tracer");
     tracerField.setAccessible(true);
     tracerField.set(null, NoopTracerFactory.create());
 
     assertThat(GlobalTracer.isRegistered()).isFalse();
 
-    Tracer tracer = TracerResolver.resolveTracer();
+    final Tracer tracer = TracerResolver.resolveTracer();
 
     assertThat(GlobalTracer.isRegistered()).isFalse();
     assertThat(tracer).isInstanceOf(DDTracer.class);
@@ -58,7 +57,7 @@ public class TracerResolverTest {
 
   @Test
   public void testRegisterTracer() throws Exception {
-    Field tracerField = GlobalTracer.class.getDeclaredField("tracer");
+    final Field tracerField = GlobalTracer.class.getDeclaredField("tracer");
     tracerField.setAccessible(true);
     tracerField.set(null, NoopTracerFactory.create());