Migrate servlet instrumentation to byte buddy.

dd-java-agent/dd-java-agent.gradle

@@ -21,7 +21,8 @@ dependencies {
   compile project(':dd-java-agent:tooling')
   compile project(':dd-trace-annotations')
 
-
+  compile project(':dd-java-agent:integrations:servlet-2')
+  compile project(':dd-java-agent:integrations:servlet-3')
   compile project(':dd-java-agent:integrations:spring-web')
 
   compile deps.bytebuddy

dd-java-agent/integrations/helpers/src/main/java/com/datadoghq/agent/integration/Servlet2Helper.java

@@ -1,94 +0,0 @@
-package com.datadoghq.agent.integration;
-
-import io.opentracing.ActiveSpan;
-import io.opentracing.NoopTracerFactory;
-import io.opentracing.SpanContext;
-import io.opentracing.Tracer;
-import io.opentracing.contrib.web.servlet.filter.HttpServletRequestExtractAdapter;
-import io.opentracing.contrib.web.servlet.filter.ServletFilterSpanDecorator;
-import io.opentracing.propagation.Format;
-import io.opentracing.tag.Tags;
-import java.util.Collections;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
-import lombok.extern.slf4j.Slf4j;
-import org.jboss.byteman.rule.Rule;
-
-/** Please be very careful not to introduce any Servlet 3 dependencies into this class. */
-@Slf4j
-public class Servlet2Helper extends OpenTracingHelper {
-
-  /**
-   * Used as a key of {@link HttpServletRequest#setAttribute(String, Object)} to inject server span
-   * context
-   */
-  public static final String SERVER_SPAN_CONTEXT =
-      Servlet2Helper.class.getName() + ".activeSpanContext";
-
-  public static final String SERVLET_OPERATION_NAME = "servlet.request";
-
-  protected final Tracer tracer;
-
-  public Servlet2Helper(final Rule rule) {
-    super(rule);
-    Tracer tracerResolved;
-    try {
-      tracerResolved = getTracer();
-      tracerResolved = tracerResolved == null ? NoopTracerFactory.create() : tracerResolved;
-    } catch (final Exception e) {
-      tracerResolved = NoopTracerFactory.create();
-      log.warn("Failed to retrieve the tracer, using a NoopTracer instead: {}", e.getMessage());
-      log.warn(e.getMessage(), e);
-    }
-    tracer = tracerResolved;
-  }
-
-  public void onRequest(final HttpServletRequest req, final HttpServletResponse resp) {
-    if (req.getAttribute(SERVER_SPAN_CONTEXT) != null) {
-      // Perhaps we're already tracing?
-      return;
-    }
-
-    final SpanContext extractedContext =
-        tracer.extract(Format.Builtin.HTTP_HEADERS, new HttpServletRequestExtractAdapter(req));
-
-    final ActiveSpan span =
-        tracer
-            .buildSpan(SERVLET_OPERATION_NAME)
-            .asChildOf(extractedContext)
-            .withTag(Tags.SPAN_KIND.getKey(), Tags.SPAN_KIND_SERVER)
-            .startActive();
-
-    req.setAttribute(SERVER_SPAN_CONTEXT, span.context());
-
-    ServletFilterSpanDecorator.STANDARD_TAGS.onRequest(req, span);
-  }
-
-  public void onError(
-      final HttpServletRequest req, final HttpServletResponse resp, final Throwable ex) {
-    if (req.getAttribute(SERVER_SPAN_CONTEXT) == null) {
-      // Doesn't look like an active span was started at the beginning
-      return;
-    }
-
-    final ActiveSpan span = tracer.activeSpan();
-    if (span != null) {
-      ServletFilterSpanDecorator.STANDARD_TAGS.onError(req, resp, ex, span);
-      span.log(Collections.singletonMap("error.object", ex));
-      span.deactivate();
-    }
-  }
-
-  public void onResponse(final HttpServletRequest req, final HttpServletResponse resp) {
-    if (req.getAttribute(SERVER_SPAN_CONTEXT) == null) {
-      // Doesn't look like an active span was started at the beginning
-      return;
-    }
-
-    final ActiveSpan span = tracer.activeSpan();
-    if (span != null) {
-      ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(req, resp, span);
-      span.deactivate();
-    }
-  }
-}

dd-java-agent/integrations/helpers/src/main/java/com/datadoghq/agent/integration/Servlet3Helper.java

@@ -1,99 +0,0 @@
-package com.datadoghq.agent.integration;
-
-import io.opentracing.ActiveSpan;
-import io.opentracing.contrib.web.servlet.filter.ServletFilterSpanDecorator;
-import java.io.IOException;
-import java.util.Collections;
-import java.util.concurrent.atomic.AtomicBoolean;
-import javax.servlet.AsyncEvent;
-import javax.servlet.AsyncListener;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
-import lombok.extern.slf4j.Slf4j;
-import org.jboss.byteman.rule.Rule;
-
-@Slf4j
-public class Servlet3Helper extends Servlet2Helper {
-
-  public Servlet3Helper(final Rule rule) {
-    super(rule);
-  }
-
-  /**
-   * The distinction with this method compared with Servlet2Helper.onResponse is the addition of the
-   * async support.
-   *
-   * @param req
-   * @param resp
-   */
-  @Override
-  public void onResponse(final HttpServletRequest req, final HttpServletResponse resp) {
-    if (req.getAttribute(SERVER_SPAN_CONTEXT) == null) {
-      // Doesn't look like an active span was started at the beginning
-      return;
-    }
-
-    final ActiveSpan span = tracer.activeSpan();
-    if (span != null) {
-      if (req.isAsyncStarted()) {
-        addAsyncListeners(req, resp, span);
-      } else {
-        ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(req, resp, span);
-      }
-      span.deactivate();
-    }
-  }
-
-  private void addAsyncListeners(
-      final HttpServletRequest req, final HttpServletResponse resp, final ActiveSpan span) {
-
-    final ActiveSpan.Continuation cont = span.capture();
-    final AtomicBoolean activated = new AtomicBoolean(false);
-    // what if async is already finished? This would not be called
-    req.getAsyncContext()
-        .addListener(
-            new AsyncListener() {
-              @Override
-              public void onComplete(final AsyncEvent event) throws IOException {
-                if (activated.compareAndSet(false, true)) {
-                  try (ActiveSpan activeSpan = cont.activate()) {
-                    ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(
-                        (HttpServletRequest) event.getSuppliedRequest(),
-                        (HttpServletResponse) event.getSuppliedResponse(),
-                        span);
-                  }
-                }
-              }
-
-              @Override
-              public void onTimeout(final AsyncEvent event) throws IOException {
-                if (activated.compareAndSet(false, true)) {
-                  try (ActiveSpan activeSpan = cont.activate()) {
-                    ServletFilterSpanDecorator.STANDARD_TAGS.onTimeout(
-                        (HttpServletRequest) event.getSuppliedRequest(),
-                        (HttpServletResponse) event.getSuppliedResponse(),
-                        event.getAsyncContext().getTimeout(),
-                        span);
-                  }
-                }
-              }
-
-              @Override
-              public void onError(final AsyncEvent event) throws IOException {
-                if (activated.compareAndSet(false, true)) {
-                  try (ActiveSpan activeSpan = cont.activate()) {
-                    ServletFilterSpanDecorator.STANDARD_TAGS.onError(
-                        (HttpServletRequest) event.getSuppliedRequest(),
-                        (HttpServletResponse) event.getSuppliedResponse(),
-                        event.getThrowable(),
-                        span);
-                    span.log(Collections.singletonMap("error.object", event.getThrowable()));
-                  }
-                }
-              }
-
-              @Override
-              public void onStartAsync(final AsyncEvent event) throws IOException {}
-            });
-  }
-}

dd-java-agent/integrations/servlet-2/servlet-2.gradle

@@ -9,3 +9,18 @@ versionScan {
     "javax.servlet.FilterChain"        : null,
   ]
 }
+
+apply from: "${rootDir}/gradle/java.gradle"
+
+dependencies {
+  compileOnly group: 'javax.servlet', name: 'servlet-api', version: '2.3'
+
+  compile project(':dd-trace')
+  compile project(':dd-java-agent:tooling')
+
+  compile deps.bytebuddy
+  compile deps.opentracing
+
+  compile group: 'io.opentracing.contrib', name: 'opentracing-web-servlet-filter', version: '0.0.9'
+  compile group: 'com.google.auto.service', name: 'auto-service', version: '1.0-rc3'
+}

dd-java-agent/integrations/servlet-2/src/main/java/dd/inst/servlet2/HttpServlet2Instrumentation.java

@@ -0,0 +1,86 @@
+package dd.inst.servlet2;
+
+import static dd.trace.ClassLoaderHasClassMatcher.classLoaderHasClasses;
+import static net.bytebuddy.matcher.ElementMatchers.isProtected;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+import static net.bytebuddy.matcher.ElementMatchers.not;
+import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
+
+import com.google.auto.service.AutoService;
+import dd.trace.Instrumenter;
+import io.opentracing.ActiveSpan;
+import io.opentracing.SpanContext;
+import io.opentracing.contrib.web.servlet.filter.HttpServletRequestExtractAdapter;
+import io.opentracing.contrib.web.servlet.filter.ServletFilterSpanDecorator;
+import io.opentracing.propagation.Format;
+import io.opentracing.tag.Tags;
+import io.opentracing.util.GlobalTracer;
+import java.util.Collections;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import net.bytebuddy.agent.builder.AgentBuilder;
+import net.bytebuddy.asm.Advice;
+
+@AutoService(Instrumenter.class)
+public final class HttpServlet2Instrumentation implements Instrumenter {
+  public static final String SERVLET_OPERATION_NAME = "servlet.request";
+
+  @Override
+  public AgentBuilder instrument(final AgentBuilder agentBuilder) {
+    return agentBuilder
+        .type(
+            named("javax.servlet.http.HttpServlet"),
+            not(classLoaderHasClasses("javax.servlet.AsyncEvent", "javax.servlet.AsyncListener"))
+                .and(
+                    classLoaderHasClasses(
+                        "javax.servlet.ServletContextEvent", "javax.servlet.FilterChain")))
+        .transform(
+            new AgentBuilder.Transformer.ForAdvice()
+                .advice(
+                    named("service")
+                        .and(takesArgument(0, named("javax.servlet.http.HttpServletRequest")))
+                        .and(takesArgument(1, named("javax.servlet.http.HttpServletResponse")))
+                        .and(isProtected()),
+                    HttpServlet2Advice.class.getName()))
+        .asDecorator();
+  }
+
+  public static class HttpServlet2Advice {
+
+    @Advice.OnMethodEnter
+    public static ActiveSpan startSpan(@Advice.Argument(0) final HttpServletRequest req) {
+
+      final SpanContext extractedContext =
+          GlobalTracer.get()
+              .extract(Format.Builtin.HTTP_HEADERS, new HttpServletRequestExtractAdapter(req));
+
+      final ActiveSpan span =
+          GlobalTracer.get()
+              .buildSpan(SERVLET_OPERATION_NAME)
+              .asChildOf(extractedContext)
+              .withTag(Tags.SPAN_KIND.getKey(), Tags.SPAN_KIND_SERVER)
+              .startActive();
+
+      ServletFilterSpanDecorator.STANDARD_TAGS.onRequest(req, span);
+      return span;
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class)
+    public static void stopSpan(
+        @Advice.Argument(0) final HttpServletRequest req,
+        @Advice.Argument(1) final HttpServletResponse resp,
+        @Advice.Enter final ActiveSpan span,
+        @Advice.Thrown final Throwable throwable) {
+
+      if (span != null) {
+        if (throwable != null) {
+          ServletFilterSpanDecorator.STANDARD_TAGS.onError(req, resp, throwable, span);
+          span.log(Collections.singletonMap("error.object", throwable));
+        } else {
+          ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(req, resp, span);
+        }
+        span.deactivate();
+      }
+    }
+  }
+}

dd-java-agent/integrations/servlet-3/servlet-3.gradle

@@ -10,3 +10,18 @@ versionScan {
     "javax.servlet.AsyncListener": null,
   ]
 }
+
+apply from: "${rootDir}/gradle/java.gradle"
+
+dependencies {
+  compileOnly group: 'javax.servlet', name: 'javax.servlet-api', version: '3.0.1'
+
+  compile project(':dd-trace')
+  compile project(':dd-java-agent:tooling')
+
+  compile deps.bytebuddy
+  compile deps.opentracing
+
+  compile group: 'io.opentracing.contrib', name: 'opentracing-web-servlet-filter', version: '0.0.9'
+  compile group: 'com.google.auto.service', name: 'auto-service', version: '1.0-rc3'
+}

dd-java-agent/integrations/servlet-3/src/main/java/dd/inst/servlet3/HttpServlet3Instrumentation.java

@@ -0,0 +1,148 @@
+package dd.inst.servlet3;
+
+import static dd.trace.ClassLoaderHasClassMatcher.classLoaderHasClasses;
+import static net.bytebuddy.matcher.ElementMatchers.isProtected;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+import static net.bytebuddy.matcher.ElementMatchers.takesArgument;
+
+import com.google.auto.service.AutoService;
+import dd.trace.Instrumenter;
+import io.opentracing.ActiveSpan;
+import io.opentracing.SpanContext;
+import io.opentracing.contrib.web.servlet.filter.HttpServletRequestExtractAdapter;
+import io.opentracing.contrib.web.servlet.filter.ServletFilterSpanDecorator;
+import io.opentracing.propagation.Format;
+import io.opentracing.tag.Tags;
+import io.opentracing.util.GlobalTracer;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.concurrent.atomic.AtomicBoolean;
+import javax.servlet.AsyncEvent;
+import javax.servlet.AsyncListener;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import net.bytebuddy.agent.builder.AgentBuilder;
+import net.bytebuddy.asm.Advice;
+
+@AutoService(Instrumenter.class)
+public final class HttpServlet3Instrumentation implements Instrumenter {
+  public static final String SERVLET_OPERATION_NAME = "servlet.request";
+
+  @Override
+  public AgentBuilder instrument(final AgentBuilder agentBuilder) {
+    return agentBuilder
+        .type(
+            named("javax.servlet.http.HttpServlet"),
+            classLoaderHasClasses("javax.servlet.AsyncEvent", "javax.servlet.AsyncListener"))
+        .transform(
+            new AgentBuilder.Transformer.ForAdvice()
+                .advice(
+                    named("service")
+                        .and(takesArgument(0, named("javax.servlet.http.HttpServletRequest")))
+                        .and(takesArgument(1, named("javax.servlet.http.HttpServletResponse")))
+                        .and(isProtected()),
+                    HttpServlet3Advice.class.getName()))
+        .asDecorator();
+  }
+
+  public static class HttpServlet3Advice {
+
+    @Advice.OnMethodEnter
+    public static ActiveSpan startSpan(@Advice.Argument(0) final HttpServletRequest req) {
+
+      final SpanContext extractedContext =
+          GlobalTracer.get()
+              .extract(Format.Builtin.HTTP_HEADERS, new HttpServletRequestExtractAdapter(req));
+
+      final ActiveSpan span =
+          GlobalTracer.get()
+              .buildSpan(SERVLET_OPERATION_NAME)
+              .asChildOf(extractedContext)
+              .withTag(Tags.SPAN_KIND.getKey(), Tags.SPAN_KIND_SERVER)
+              .startActive();
+
+      ServletFilterSpanDecorator.STANDARD_TAGS.onRequest(req, span);
+      return span;
+    }
+
+    @Advice.OnMethodExit(onThrowable = Throwable.class)
+    public static void stopSpan(
+        @Advice.Argument(0) final HttpServletRequest req,
+        @Advice.Argument(1) final HttpServletResponse resp,
+        @Advice.Enter final ActiveSpan span,
+        @Advice.Thrown final Throwable throwable) {
+
+      if (span != null) {
+        if (throwable != null) {
+          ServletFilterSpanDecorator.STANDARD_TAGS.onError(req, resp, throwable, span);
+          span.log(Collections.singletonMap("error.object", throwable));
+        } else if (req.isAsyncStarted()) {
+          final ActiveSpan.Continuation cont = span.capture();
+          final AtomicBoolean activated = new AtomicBoolean(false);
+          // what if async is already finished? This would not be called
+          req.getAsyncContext().addListener(new TagSettingAsyncListener(activated, cont, span));
+        } else {
+          ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(req, resp, span);
+        }
+        span.deactivate();
+      }
+    }
+
+    public static class TagSettingAsyncListener implements AsyncListener {
+      private final AtomicBoolean activated;
+      private final ActiveSpan.Continuation cont;
+      private final ActiveSpan span;
+
+      public TagSettingAsyncListener(
+          final AtomicBoolean activated,
+          final ActiveSpan.Continuation cont,
+          final ActiveSpan span) {
+        this.activated = activated;
+        this.cont = cont;
+        this.span = span;
+      }
+
+      @Override
+      public void onComplete(final AsyncEvent event) throws IOException {
+        if (activated.compareAndSet(false, true)) {
+          try (ActiveSpan activeSpan = cont.activate()) {
+            ServletFilterSpanDecorator.STANDARD_TAGS.onResponse(
+                (HttpServletRequest) event.getSuppliedRequest(),
+                (HttpServletResponse) event.getSuppliedResponse(),
+                span);
+          }
+        }
+      }
+
+      @Override
+      public void onTimeout(final AsyncEvent event) throws IOException {
+        if (activated.compareAndSet(false, true)) {
+          try (ActiveSpan activeSpan = cont.activate()) {
+            ServletFilterSpanDecorator.STANDARD_TAGS.onTimeout(
+                (HttpServletRequest) event.getSuppliedRequest(),
+                (HttpServletResponse) event.getSuppliedResponse(),
+                event.getAsyncContext().getTimeout(),
+                span);
+          }
+        }
+      }
+
+      @Override
+      public void onError(final AsyncEvent event) throws IOException {
+        if (event.getThrowable() != null && activated.compareAndSet(false, true)) {
+          try (ActiveSpan activeSpan = cont.activate()) {
+            ServletFilterSpanDecorator.STANDARD_TAGS.onError(
+                (HttpServletRequest) event.getSuppliedRequest(),
+                (HttpServletResponse) event.getSuppliedResponse(),
+                event.getThrowable(),
+                span);
+            span.log(Collections.singletonMap("error.object", event.getThrowable()));
+          }
+        }
+      }
+
+      @Override
+      public void onStartAsync(final AsyncEvent event) throws IOException {}
+    }
+  }
+}

dd-java-agent/integrations/spring-web/src/main/java/dd/inst/springweb/SpringWebInstrumentation.java

@@ -1,5 +1,6 @@
 package dd.inst.springweb;
 
+import static dd.trace.ClassLoaderHasClassWithFieldMatcher.classLoaderHasClassWithField;
 import static net.bytebuddy.matcher.ElementMatchers.hasSuperType;
 import static net.bytebuddy.matcher.ElementMatchers.isInterface;
 import static net.bytebuddy.matcher.ElementMatchers.isMethod;
@@ -31,7 +32,10 @@ public final class SpringWebInstrumentation implements Instrumenter {
     return agentBuilder
         .type(
             not(isInterface())
-                .and(hasSuperType(named("org.springframework.web.servlet.HandlerAdapter"))))
+                .and(hasSuperType(named("org.springframework.web.servlet.HandlerAdapter"))),
+            classLoaderHasClassWithField(
+                "org.springframework.web.servlet.HandlerMapping",
+                "BEST_MATCHING_PATTERN_ATTRIBUTE"))
         .transform(
             new AgentBuilder.Transformer.ForAdvice()
                 .advice(

dd-java-agent/src/main/resources/initializer-rules.btm

@@ -80,15 +80,3 @@ IF TRUE
 DO
   com.datadoghq.agent.InstrumentationRulesManager.registerClassLoad($0);
 ENDRULE
-
-
-# Instrument Servlet
-# ===========================
-RULE HttpServlet-init
-CLASS ^javax.servlet.http.HttpServlet
-METHOD <init>
-AT EXIT
-IF TRUE
-DO
-  com.datadoghq.agent.InstrumentationRulesManager.registerClassLoad($0);
-ENDRULE

dd-java-agent/src/main/resources/integration-rules.btm

@@ -106,73 +106,3 @@ IF TRUE
 DO
   patch($0)
 ENDRULE
-
-# Instrument Servlet 2
-# ===========================
-RULE HttpServlet-2.service-entry
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet2Helper
-COMPILE
-AT ENTRY
-IF TRUE
-DO
-  onRequest($1, $2)
-ENDRULE
-
-RULE HttpServlet-2.service-exit
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet2Helper
-COMPILE
-AT EXIT
-IF TRUE
-DO
-  onResponse($1, $2)
-ENDRULE
-
-RULE HttpServlet-2.service-error
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet2Helper
-COMPILE
-AT EXCEPTION EXIT
-IF TRUE
-DO
-  onError($1, $2, $^)
-ENDRULE
-
-# Instrument Servlet 3
-# ===========================
-RULE HttpServlet-3.service-entry
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet3Helper
-COMPILE
-AT ENTRY
-IF TRUE
-DO
-  onRequest($1, $2)
-ENDRULE
-
-RULE HttpServlet-3.service-exit
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet3Helper
-COMPILE
-AT EXIT
-IF TRUE
-DO
-  onResponse($1, $2)
-ENDRULE
-
-RULE HttpServlet-3.service-error
-CLASS ^javax.servlet.http.HttpServlet
-METHOD service(HttpServletRequest, HttpServletResponse)
-HELPER com.datadoghq.agent.integration.Servlet3Helper
-COMPILE
-AT EXCEPTION EXIT
-IF TRUE
-DO
-  onError($1, $2, $^)
-ENDRULE

dd-java-agent/tooling/src/main/java/dd/trace/ClassLoaderHasClassMatcher.java

@@ -0,0 +1,32 @@
+package dd.trace;
+
+import net.bytebuddy.matcher.ElementMatcher;
+
+public class ClassLoaderHasClassMatcher extends ElementMatcher.Junction.AbstractBase<ClassLoader> {
+
+  private final String[] names;
+
+  private ClassLoaderHasClassMatcher(final String... names) {
+    this.names = names;
+  }
+
+  public static ElementMatcher.Junction.AbstractBase<ClassLoader> classLoaderHasClasses(
+      final String... names) {
+    return new ClassLoaderHasClassMatcher(names);
+  }
+
+  @Override
+  public boolean matches(final ClassLoader target) {
+    try {
+      if (target != null) {
+        for (final String name : names) {
+          Class.forName(name, false, target);
+        }
+        return true;
+      }
+      return false;
+    } catch (final ClassNotFoundException e) {
+      return false;
+    }
+  }
+}

dd-java-agent/tooling/src/main/java/dd/trace/ClassLoaderHasClassWithFieldMatcher.java

@@ -0,0 +1,36 @@
+package dd.trace;
+
+import net.bytebuddy.matcher.ElementMatcher;
+
+public class ClassLoaderHasClassWithFieldMatcher
+    extends ElementMatcher.Junction.AbstractBase<ClassLoader> {
+
+  private final String className;
+  private final String fieldName;
+
+  private ClassLoaderHasClassWithFieldMatcher(final String className, final String fieldName) {
+    this.className = className;
+    this.fieldName = fieldName;
+  }
+
+  public static AbstractBase<ClassLoader> classLoaderHasClassWithField(
+      final String className, final String fieldName) {
+    return new ClassLoaderHasClassWithFieldMatcher(className, fieldName);
+  }
+
+  @Override
+  public boolean matches(final ClassLoader target) {
+    try {
+      if (target != null) {
+        final Class<?> aClass = Class.forName(className, false, target);
+        aClass.getDeclaredField(fieldName);
+        return true;
+      }
+      return false;
+    } catch (final ClassNotFoundException e) {
+      return false;
+    } catch (final NoSuchFieldException e) {
+      return false;
+    }
+  }
+}