[servlet] change the resource name for servlet integration (404 grouping)

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

@@ -11,3 +11,5 @@ decorators:
   - type: DBTypeDecorator
   - type: DBStatementAsResourceName
   - type: OperationDecorator
+  - type: Status404Decorator
+  - type: URLAsResourceName

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

@@ -11,7 +11,7 @@ public abstract class AbstractDecorator {
 
   private String matchingTag;
 
-  private String matchingValue;
+  private Object matchingValue;
 
   private String setTag;
 
@@ -45,11 +45,11 @@ public abstract class AbstractDecorator {
     this.matchingTag = tag;
   }
 
-  public String getMatchingValue() {
+  public Object getMatchingValue() {
     return matchingValue;
   }
 
-  public void setMatchingValue(final String value) {
+  public void setMatchingValue(final Object value) {
     this.matchingValue = value;
   }
 

dd-trace/src/main/java/com/datadoghq/trace/integration/Status404Decorator.java

@@ -0,0 +1,16 @@
+package com.datadoghq.trace.integration;
+
+import com.datadoghq.trace.DDTags;
+import io.opentracing.tag.Tags;
+
+/** This span decorator protect against spam on the resource name */
+public class Status404Decorator extends AbstractDecorator {
+
+  public Status404Decorator() {
+    super();
+    this.setMatchingTag(Tags.HTTP_STATUS.getKey());
+    this.setMatchingValue(404);
+    this.setSetTag(DDTags.RESOURCE_NAME);
+    this.setSetValue("404");
+  }
+}

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

@@ -5,6 +5,7 @@ import com.datadoghq.trace.DDTags;
 import io.opentracing.tag.Tags;
 import java.net.MalformedURLException;
 
+/** Decorator for servlet contrib */
 public class URLAsResourceName extends AbstractDecorator {
 
   public URLAsResourceName() {
@@ -16,11 +17,14 @@ public class URLAsResourceName extends AbstractDecorator {
   @Override
   public boolean afterSetTag(final DDSpanContext context, final String tag, final Object value) {
     //Assign resource name
-    try {
-      final String path = new java.net.URL(String.valueOf(value)).getPath();
-      context.setResourceName(path);
-    } catch (final MalformedURLException e) {
-      context.setResourceName(String.valueOf(value));
+    if (context.getTags().containsKey(Tags.COMPONENT.getKey())
+        && "java-web-servlet".equals(context.getTags().get(Tags.COMPONENT.getKey()))) {
+      try {
+        final String path = new java.net.URL(String.valueOf(value)).getPath();
+        context.setResourceName(path);
+      } catch (final MalformedURLException e) {
+        context.setResourceName(String.valueOf(value));
+      }
     }
     return true;
   }

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

@@ -109,4 +109,45 @@ class SpanDecoratorTest extends Specification {
     where:
     something = "fake-query"
   }
+
+  def "set 404 as a resource on a 404 issue"() {
+    setup:
+    def tracer = new DDTracer()
+    def span = SpanFactory.newSpanOf(tracer)
+    tracer.addDecorator(new Status404Decorator())
+
+    when:
+    Tags.HTTP_STATUS.set(span, 404)
+
+    then:
+    span.getResourceName() == "404"
+
+  }
+
+  def "set url as a resource only for the servlet integration"() {
+    setup:
+    def tracer = new DDTracer()
+    def span = SpanFactory.newSpanOf(tracer)
+    tracer.addDecorator(new URLAsResourceName())
+
+    when:
+    span.setResourceName("change-me")
+    Tags.COMPONENT.set(span, "java-web-servlet")
+    Tags.HTTP_URL.set(span, something)
+
+    then:
+    span.getResourceName() == something
+
+    when:
+    span.setResourceName("change-me")
+    Tags.COMPONENT.set(span, "other-contrib")
+    Tags.HTTP_URL.set(span, something)
+
+    then:
+    span.getResourceName() == "change-me"
+
+
+    where:
+    something = "fake"
+  }
 }