Get and test metrics for injection failures and skips

Author: sarahchen6

dd-java-agent/instrumentation/servlet/request-3/src/main/java/datadog/trace/instrumentation/servlet3/RumHttpServletResponseWrapper.java

@@ -23,37 +23,48 @@ public RumHttpServletResponseWrapper(HttpServletResponse response) {
   @Override
   public ServletOutputStream getOutputStream() throws IOException {
     if (!shouldInject) {
+      RumInjector.getTelemetryCollector().onInjectionSkipped();
       return super.getOutputStream();
     }
     if (outputStream == null) {
-      String encoding = getCharacterEncoding();
-      if (encoding == null) {
-        encoding = Charset.defaultCharset().name();
+      try {
+        String encoding = getCharacterEncoding();
+        if (encoding == null) {
+          encoding = Charset.defaultCharset().name();
+        }
+        outputStream =
+            new WrappedServletOutputStream(
+                super.getOutputStream(),
+                rumInjector.getMarkerBytes(encoding),
+                rumInjector.getSnippetBytes(encoding),
+                this::onInjected);
+      } catch (Exception e) {
+        RumInjector.getTelemetryCollector().onInjectionFailed();
+        throw e;
       }
-      outputStream =
-          new WrappedServletOutputStream(
-              super.getOutputStream(),
-              rumInjector.getMarkerBytes(encoding),
-              rumInjector.getSnippetBytes(encoding),
-              this::onInjected);
     }
     return outputStream;
   }
 
   @Override
   public PrintWriter getWriter() throws IOException {
-    final PrintWriter delegate = super.getWriter();
     if (!shouldInject) {
-      return delegate;
+      RumInjector.getTelemetryCollector().onInjectionSkipped();
+      return super.getWriter();
     }
     if (printWriter == null) {
-      printWriter =
-          new PrintWriter(
-              new InjectingPipeWriter(
-                  delegate,
-                  rumInjector.getMarkerChars(),
-                  rumInjector.getSnippetChars(),
-                  this::onInjected));
+      try {
+        printWriter =
+            new PrintWriter(
+                new InjectingPipeWriter(
+                    super.getWriter(),
+                    rumInjector.getMarkerChars(),
+                    rumInjector.getSnippetChars(),
+                    this::onInjected));
+      } catch (Exception e) {
+        RumInjector.getTelemetryCollector().onInjectionFailed();
+        throw e;
+      }
     }
     return printWriter;
   }

dd-java-agent/instrumentation/servlet/request-3/src/test/groovy/RumHttpServletResponseWrapperTest.groovy

@@ -0,0 +1,85 @@
+import datadog.trace.agent.test.AgentTestRunner
+import datadog.trace.api.rum.RumInjector
+import datadog.trace.api.rum.RumTelemetryCollector
+import datadog.trace.instrumentation.servlet3.RumHttpServletResponseWrapper
+import spock.lang.Subject
+
+import javax.servlet.http.HttpServletResponse
+
+class RumHttpServletResponseWrapperTest extends AgentTestRunner {
+
+  def mockResponse = Mock(HttpServletResponse)
+  def mockTelemetryCollector = Mock(RumTelemetryCollector)
+
+  @Subject
+  RumHttpServletResponseWrapper wrapper
+
+  void setup() {
+    wrapper = new RumHttpServletResponseWrapper(mockResponse)
+    RumInjector.setTelemetryCollector(mockTelemetryCollector)
+  }
+
+  void cleanup() {
+    RumInjector.setTelemetryCollector(RumTelemetryCollector.NO_OP)
+  }
+
+  void 'onInjected calls telemetry collector onInjectionSucceed'() {
+    when:
+    wrapper.onInjected()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSucceed()
+  }
+
+  void 'getOutputStream with non-HTML content reports skipped'() {
+    setup:
+    wrapper.setContentType("text/plain")
+
+    when:
+    wrapper.getOutputStream()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSkipped()
+    1 * mockResponse.getOutputStream()
+  }
+
+  void 'getWriter with non-HTML content reports skipped'() {
+    setup:
+    wrapper.setContentType("text/plain")
+
+    when:
+    wrapper.getWriter()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSkipped()
+    1 * mockResponse.getWriter()
+  }
+
+  void 'getOutputStream exception reports failure'() {
+    setup:
+    wrapper.setContentType("text/html")
+    mockResponse.getOutputStream() >> { throw new IOException("stream error") }
+
+    when:
+    try {
+      wrapper.getOutputStream()
+    } catch (IOException ignored) {}
+
+    then:
+    1 * mockTelemetryCollector.onInjectionFailed()
+  }
+
+  void 'getWriter exception reports failure'() {
+    setup:
+    wrapper.setContentType("text/html")
+    mockResponse.getWriter() >> { throw new IOException("writer error") }
+
+    when:
+    try {
+      wrapper.getWriter()
+    } catch (IOException ignored) {}
+
+    then:
+    1 * mockTelemetryCollector.onInjectionFailed()
+  }
+}

dd-java-agent/instrumentation/servlet/request-5/src/main/java/datadog/trace/instrumentation/servlet5/RumHttpServletResponseWrapper.java

@@ -23,37 +23,48 @@ public RumHttpServletResponseWrapper(HttpServletResponse response) {
   @Override
   public ServletOutputStream getOutputStream() throws IOException {
     if (!shouldInject) {
+      RumInjector.getTelemetryCollector().onInjectionSkipped();
       return super.getOutputStream();
     }
     if (outputStream == null) {
-      String encoding = getCharacterEncoding();
-      if (encoding == null) {
-        encoding = Charset.defaultCharset().name();
+      try {
+        String encoding = getCharacterEncoding();
+        if (encoding == null) {
+          encoding = Charset.defaultCharset().name();
+        }
+        outputStream =
+            new WrappedServletOutputStream(
+                super.getOutputStream(),
+                rumInjector.getMarkerBytes(encoding),
+                rumInjector.getSnippetBytes(encoding),
+                this::onInjected);
+      } catch (Exception e) {
+        RumInjector.getTelemetryCollector().onInjectionFailed();
+        throw e;
       }
-      outputStream =
-          new WrappedServletOutputStream(
-              super.getOutputStream(),
-              rumInjector.getMarkerBytes(encoding),
-              rumInjector.getSnippetBytes(encoding),
-              this::onInjected);
     }
     return outputStream;
   }
 
   @Override
   public PrintWriter getWriter() throws IOException {
-    final PrintWriter delegate = super.getWriter();
     if (!shouldInject) {
-      return delegate;
+      RumInjector.getTelemetryCollector().onInjectionSkipped();
+      return super.getWriter();
     }
     if (printWriter == null) {
-      printWriter =
-          new PrintWriter(
-              new InjectingPipeWriter(
-                  delegate,
-                  rumInjector.getMarkerChars(),
-                  rumInjector.getSnippetChars(),
-                  this::onInjected));
+      try {
+        printWriter =
+            new PrintWriter(
+                new InjectingPipeWriter(
+                    super.getWriter(),
+                    rumInjector.getMarkerChars(),
+                    rumInjector.getSnippetChars(),
+                    this::onInjected));
+      } catch (Exception e) {
+        RumInjector.getTelemetryCollector().onInjectionFailed();
+        throw e;
+      }
     }
     return printWriter;
   }

dd-java-agent/instrumentation/servlet/request-5/src/test/groovy/RumHttpServletResponseWrapperTest.groovy

@@ -0,0 +1,85 @@
+import datadog.trace.agent.test.AgentTestRunner
+import datadog.trace.api.rum.RumInjector
+import datadog.trace.api.rum.RumTelemetryCollector
+import datadog.trace.instrumentation.servlet5.RumHttpServletResponseWrapper
+import spock.lang.Subject
+
+import jakarta.servlet.http.HttpServletResponse
+
+class RumHttpServletResponseWrapperTest extends AgentTestRunner {
+
+  def mockResponse = Mock(HttpServletResponse)
+  def mockTelemetryCollector = Mock(RumTelemetryCollector)
+
+  @Subject
+  RumHttpServletResponseWrapper wrapper
+
+  void setup() {
+    wrapper = new RumHttpServletResponseWrapper(mockResponse)
+    RumInjector.setTelemetryCollector(mockTelemetryCollector)
+  }
+
+  void cleanup() {
+    RumInjector.setTelemetryCollector(RumTelemetryCollector.NO_OP)
+  }
+
+  void 'onInjected calls telemetry collector onInjectionSucceed'() {
+    when:
+    wrapper.onInjected()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSucceed()
+  }
+
+  void 'getOutputStream with non-HTML content reports skipped'() {
+    setup:
+    wrapper.setContentType("text/plain")
+
+    when:
+    wrapper.getOutputStream()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSkipped()
+    1 * mockResponse.getOutputStream()
+  }
+
+  void 'getWriter with non-HTML content reports skipped'() {
+    setup:
+    wrapper.setContentType("text/plain")
+
+    when:
+    wrapper.getWriter()
+
+    then:
+    1 * mockTelemetryCollector.onInjectionSkipped()
+    1 * mockResponse.getWriter()
+  }
+
+  void 'getOutputStream exception reports failure'() {
+    setup:
+    wrapper.setContentType("text/html")
+    mockResponse.getOutputStream() >> { throw new IOException("stream error") }
+
+    when:
+    try {
+      wrapper.getOutputStream()
+    } catch (IOException ignored) {}
+
+    then:
+    1 * mockTelemetryCollector.onInjectionFailed()
+  }
+
+  void 'getWriter exception reports failure'() {
+    setup:
+    wrapper.setContentType("text/html")
+    mockResponse.getWriter() >> { throw new IOException("writer error") }
+
+    when:
+    try {
+      wrapper.getWriter()
+    } catch (IOException ignored) {}
+
+    then:
+    1 * mockTelemetryCollector.onInjectionFailed()
+  }
+}