Library instrumentation for Java Servlet 3.0 Filters.

instrumentation/servlet/servlet-3.0/library/build.gradle.kts

@@ -0,0 +1,11 @@
+plugins {
+  id("otel.library-instrumentation")
+}
+
+dependencies {
+  library("javax.servlet:javax.servlet-api:3.0.1")
+
+  // FIXME: These dependencies need to be shadowed into the library.
+  library(project(":instrumentation:servlet:servlet-3.0:javaagent"))
+  library(project(":instrumentation:servlet:servlet-common:javaagent"))
+}

instrumentation/servlet/servlet-3.0/library/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/OpenTelemetryServletFilter.java

@@ -0,0 +1,69 @@
+package io.opentelemetry.javaagent.instrumentation.servlet.v3_0;
+
+import static io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Singletons.helper;
+
+import io.opentelemetry.context.Context;
+import io.opentelemetry.context.Scope;
+import io.opentelemetry.javaagent.instrumentation.servlet.ServletRequestContext;
+import java.io.IOException;
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * OpenTelemetry Library instrumentation for Java Servlet based applications that can't use a Java
+ * Agent. Due to inherit limitations in the servlet filter API, instrumenting at the filter level
+ * will miss anything that happens earlier in the filter stack or problems handled directly by the
+ * app server. For this reason, Java Agent instrumentation is preferred when possible.
+ */
+public class OpenTelemetryServletFilter implements Filter {
+
+  @Override
+  public void init(FilterConfig filterConfig) throws ServletException {}
+
+  @Override
+  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+      throws IOException, ServletException {
+    // Only HttpServlets are supported.
+    if (!(request instanceof HttpServletRequest && response instanceof HttpServletResponse)) {
+      chain.doFilter(request, response);
+      return;
+    }
+
+    HttpServletRequest httpRequest = (HttpServletRequest) request;
+    HttpServletResponse httpResponse = (HttpServletResponse) response;
+    ServletRequestContext<HttpServletRequest> requestContext =
+        new ServletRequestContext<>(httpRequest, this);
+
+    // Bail if we shouldn't start a new span.
+    if (!helper().shouldStart(Context.current(), requestContext)) {
+      chain.doFilter(request, response);
+      return;
+    }
+
+    Context spanContext = helper().start(Context.current(), requestContext);
+    helper().setAsyncListenerResponse(spanContext, (HttpServletResponse) response);
+
+    // Not using try-with-resources to match the api usage of Servlet3Advice.
+    // (helper().end is responsible for closing the scope.)
+    Scope scope = spanContext.makeCurrent();
+    Throwable throwable = null;
+    try {
+      chain.doFilter(
+          new OtelHttpServletRequest((HttpServletRequest) request), response);
+    } catch (Throwable e) {
+      throwable = e;
+      throw e;
+    } finally {
+      helper().end(requestContext, httpRequest, httpResponse, throwable, true, spanContext, scope);
+    }
+  }
+
+  @Override
+  public void destroy() {}
+}

instrumentation/servlet/servlet-3.0/library/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/OtelAsyncContext.java

@@ -0,0 +1,85 @@
+package io.opentelemetry.javaagent.instrumentation.servlet.v3_0;
+
+import static io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Singletons.helper;
+
+import javax.servlet.AsyncContext;
+import javax.servlet.AsyncListener;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+/// Delegates all methods except [#start(Runnable) which wraps the [Runnable].
+public class OtelAsyncContext implements AsyncContext {
+  private final AsyncContext delegate;
+
+  public OtelAsyncContext(AsyncContext delegate) {
+    this.delegate = delegate;
+  }
+
+  @Override
+  public ServletRequest getRequest() {
+    return delegate.getRequest();
+  }
+
+  @Override
+  public ServletResponse getResponse() {
+    return delegate.getResponse();
+  }
+
+  @Override
+  public boolean hasOriginalRequestAndResponse() {
+    return delegate.hasOriginalRequestAndResponse();
+  }
+
+  @Override
+  public void dispatch() {
+    delegate.dispatch();
+  }
+
+  @Override
+  public void dispatch(String path) {
+    delegate.dispatch(path);
+  }
+
+  @Override
+  public void dispatch(ServletContext context, String path) {
+    delegate.dispatch(context, path);
+  }
+
+  @Override
+  public void complete() {
+    delegate.complete();
+  }
+
+  @Override
+  public void start(Runnable run) {
+    delegate.start(helper().wrapAsyncRunnable(run));
+  }
+
+  @Override
+  public void addListener(AsyncListener listener) {
+    delegate.addListener(listener);
+  }
+
+  @Override
+  public void addListener(
+      AsyncListener listener, ServletRequest servletRequest, ServletResponse servletResponse) {
+    delegate.addListener(listener, servletRequest, servletResponse);
+  }
+
+  @Override
+  public <T extends AsyncListener> T createListener(Class<T> clazz) throws ServletException {
+    return delegate.createListener(clazz);
+  }
+
+  @Override
+  public void setTimeout(long timeout) {
+    delegate.setTimeout(timeout);
+  }
+
+  @Override
+  public long getTimeout() {
+    return delegate.getTimeout();
+  }
+}

instrumentation/servlet/servlet-3.0/library/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/OtelHttpServletRequest.java

@@ -0,0 +1,43 @@
+package io.opentelemetry.javaagent.instrumentation.servlet.v3_0;
+
+import static io.opentelemetry.javaagent.instrumentation.servlet.v3_0.Servlet3Singletons.helper;
+
+import io.opentelemetry.context.Context;
+import javax.servlet.AsyncContext;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletRequestWrapper;
+
+/// Wrapper around [HttpServletRequest] that attaches an async listener if [#startAsync()] is
+/// invoked and a wrapper around [#getAsyncContext()] to capture exceptions from async [Runnable]s.
+public class OtelHttpServletRequest extends HttpServletRequestWrapper {
+
+  public OtelHttpServletRequest(HttpServletRequest request) {
+    super(request);
+  }
+
+  @Override
+  public AsyncContext getAsyncContext() {
+    return new OtelAsyncContext(super.getAsyncContext());
+  }
+
+  @Override
+  public AsyncContext startAsync() throws IllegalStateException {
+    try {
+      return super.startAsync();
+    } finally {
+      helper().attachAsyncListener(this, Context.current());
+    }
+  }
+
+  @Override
+  public AsyncContext startAsync(ServletRequest servletRequest, ServletResponse servletResponse)
+      throws IllegalStateException {
+    try {
+      return super.startAsync(servletRequest, servletResponse);
+    } finally {
+      helper().attachAsyncListener(this, Context.current());
+    }
+  }
+}

settings.gradle.kts

@@ -590,6 +590,7 @@ include(":instrumentation:scala-fork-join-2.8:javaagent")
 include(":instrumentation:servlet:servlet-2.2:javaagent")
 include(":instrumentation:servlet:servlet-3.0:javaagent")
 include(":instrumentation:servlet:servlet-3.0:javaagent-unit-tests")
+include(":instrumentation:servlet:servlet-3.0:library")
 include(":instrumentation:servlet:servlet-3.0:testing")
 include(":instrumentation:servlet:servlet-5.0:javaagent")
 include(":instrumentation:servlet:servlet-5.0:javaagent-unit-tests")