Merge pull request #463 from DataDog/ark/dd-global-tracer

Datadog Global Tracer

Author: realark

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/TracerInstaller.java

@@ -1,20 +1,19 @@
 package datadog.trace.agent.tooling;
 
 import datadog.opentracing.DDTracer;
-import io.opentracing.Tracer;
-import io.opentracing.util.GlobalTracer;
 import lombok.extern.slf4j.Slf4j;
 
 @Slf4j
 public class TracerInstaller {
   /** Register a global tracer if no global tracer is already registered. */
   public static synchronized void installGlobalTracer() {
-    if (!GlobalTracer.isRegistered()) {
-      final Tracer resolved = new DDTracer();
+    if (!io.opentracing.util.GlobalTracer.isRegistered()) {
+      final DDTracer tracer = new DDTracer();
       try {
-        GlobalTracer.register(resolved);
+        io.opentracing.util.GlobalTracer.register(tracer);
+        datadog.trace.api.GlobalTracer.registerIfAbsent(tracer);
       } catch (final RuntimeException re) {
-        log.warn("Failed to register tracer '" + resolved + "'", re);
+        log.warn("Failed to register tracer '" + tracer + "'", re);
       }
     } else {
       log.debug("GlobalTracer already registered.");
@@ -23,7 +22,10 @@ public static synchronized void installGlobalTracer() {
 
   public static void logVersionInfo() {
     VersionLogger.logAllVersions();
-    log.debug(GlobalTracer.class.getName() + " loaded on " + GlobalTracer.class.getClassLoader());
+    log.debug(
+        io.opentracing.util.GlobalTracer.class.getName()
+            + " loaded on "
+            + io.opentracing.util.GlobalTracer.class.getClassLoader());
     log.debug(
         AgentInstaller.class.getName() + " loaded on " + AgentInstaller.class.getClassLoader());
   }

dd-java-agent/testing/src/main/java/datadog/trace/agent/test/AgentTestRunner.java

@@ -7,6 +7,7 @@
 import datadog.opentracing.DDTracer;
 import datadog.trace.agent.tooling.AgentInstaller;
 import datadog.trace.agent.tooling.Instrumenter;
+import datadog.trace.api.GlobalTracer;
 import datadog.trace.common.writer.ListWriter;
 import datadog.trace.common.writer.Writer;
 import io.opentracing.Tracer;
@@ -84,6 +85,7 @@ public boolean add(final List<DDSpan> trace) {
         };
     TEST_TRACER = new DDTracer(TEST_WRITER);
     TestUtils.registerOrReplaceGlobalTracer((Tracer) TEST_TRACER);
+    GlobalTracer.registerIfAbsent((DDTracer) TEST_TRACER);
   }
 
   protected static Tracer getTestTracer() {

dd-trace-api/src/main/java/datadog/trace/api/CorrelationIdentifier.java

@@ -1,45 +1,16 @@
 package datadog.trace.api;
 
-import java.util.concurrent.atomic.AtomicReference;
-
 /**
  * Utility class to access the active trace and span ids.
  *
  * <p>Intended for use with MDC frameworks.
  */
 public class CorrelationIdentifier {
-  private static final AtomicReference<Provider> provider = new AtomicReference<>(Provider.NO_OP);
-
-  public static void registerIfAbsent(Provider p) {
-    if (p != null && p != Provider.NO_OP) {
-      provider.compareAndSet(Provider.NO_OP, p);
-    }
-  }
-
   public static String getTraceId() {
-    return provider.get().getTraceId();
+    return GlobalTracer.get().getTraceId();
   }
 
   public static String getSpanId() {
-    return provider.get().getSpanId();
-  }
-
-  public interface Provider {
-    String getTraceId();
-
-    String getSpanId();
-
-    Provider NO_OP =
-        new Provider() {
-          @Override
-          public String getTraceId() {
-            return "0";
-          }
-
-          @Override
-          public String getSpanId() {
-            return "0";
-          }
-        };
+    return GlobalTracer.get().getSpanId();
   }
 }

dd-trace-api/src/main/java/datadog/trace/api/GlobalTracer.java

@@ -0,0 +1,41 @@
+package datadog.trace.api;
+
+import datadog.trace.api.interceptor.TraceInterceptor;
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * A global reference to the registered Datadog tracer.
+ *
+ * <p>OpenTracing's GlobalTracer cannot be cast to its DDTracer implementation, so this class exists
+ * to provide a global window to datadog-specific features.
+ */
+public class GlobalTracer {
+  private static final Tracer NO_OP =
+      new Tracer() {
+        @Override
+        public String getTraceId() {
+          return "0";
+        }
+
+        @Override
+        public String getSpanId() {
+          return "0";
+        }
+
+        @Override
+        public boolean addTraceInterceptor(TraceInterceptor traceInterceptor) {
+          return false;
+        }
+      };
+  private static final AtomicReference<Tracer> provider = new AtomicReference<>(NO_OP);
+
+  public static void registerIfAbsent(Tracer p) {
+    if (p != null && p != NO_OP) {
+      provider.compareAndSet(NO_OP, p);
+    }
+  }
+
+  public static Tracer get() {
+    return provider.get();
+  }
+}

dd-trace-api/src/main/java/datadog/trace/api/Tracer.java

@@ -0,0 +1,24 @@
+package datadog.trace.api;
+
+import datadog.trace.api.interceptor.TraceInterceptor;
+
+/** A class with Datadog tracer features. */
+public interface Tracer {
+
+  /** Get the trace id of the active trace. Returns 0 if there is no active trace. */
+  String getTraceId();
+
+  /**
+   * Get the span id of the active span of the active trace. Returns 0 if there is no active trace.
+   */
+  String getSpanId();
+
+  /**
+   * Add a new interceptor to the tracer. Interceptors with duplicate priority to existing ones are
+   * ignored.
+   *
+   * @param traceInterceptor
+   * @return false if an interceptor with same priority exists.
+   */
+  boolean addTraceInterceptor(TraceInterceptor traceInterceptor);
+}

dd-trace-ot/src/main/java/datadog/opentracing/DDTracer.java

@@ -13,7 +13,6 @@
 import datadog.opentracing.propagation.HTTPCodec;
 import datadog.opentracing.scopemanager.ContextualScopeManager;
 import datadog.opentracing.scopemanager.ScopeContext;
-import datadog.trace.api.CorrelationIdentifier;
 import datadog.trace.api.interceptor.MutableSpan;
 import datadog.trace.api.interceptor.TraceInterceptor;
 import datadog.trace.api.sampling.PrioritySampling;
@@ -49,7 +48,7 @@
 
 /** DDTracer makes it easy to send traces and span to DD using the OpenTracing API. */
 @Slf4j
-public class DDTracer implements io.opentracing.Tracer, Closeable {
+public class DDTracer implements io.opentracing.Tracer, Closeable, datadog.trace.api.Tracer {
 
   public static final String UNASSIGNED_DEFAULT_SERVICE_NAME = "unnamed-java-app";
 
@@ -162,8 +161,6 @@ public void run() {
       addDecorator(decorator);
     }
 
-    CorrelationIdentifier.registerIfAbsent(OTTraceCorrelation.INSTANCE);
-
     log.info("New instance: {}", this);
   }
 
@@ -202,17 +199,6 @@ public void addDecorator(final AbstractDecorator decorator) {
     spanContextDecorators.put(decorator.getMatchingTag(), list);
   }
 
-  /**
-   * Add a new interceptor to the tracer. Interceptors with duplicate priority to existing ones are
-   * ignored.
-   *
-   * @param interceptor
-   * @return false if an interceptor with same priority exists.
-   */
-  public boolean addInterceptor(final TraceInterceptor interceptor) {
-    return interceptors.add(interceptor);
-  }
-
   public void addScopeContext(final ScopeContext context) {
     scopeManager.addScopeContext(context);
   }
@@ -227,7 +213,7 @@ public void registerClassLoader(final ClassLoader classLoader) {
     try {
       for (final TraceInterceptor interceptor :
           ServiceLoader.load(TraceInterceptor.class, classLoader)) {
-        addInterceptor(interceptor);
+        addTraceInterceptor(interceptor);
       }
     } catch (final ServiceConfigurationError e) {
       log.warn("Problem loading TraceInterceptor for classLoader: " + classLoader, e);
@@ -308,6 +294,29 @@ void incrementTraceCount() {
     traceCount.incrementAndGet();
   }
 
+  @Override
+  public String getTraceId() {
+    final Span activeSpan = this.activeSpan();
+    if (activeSpan instanceof DDSpan) {
+      return ((DDSpan) activeSpan).getTraceId();
+    }
+    return "0";
+  }
+
+  @Override
+  public String getSpanId() {
+    final Span activeSpan = this.activeSpan();
+    if (activeSpan instanceof DDSpan) {
+      return ((DDSpan) activeSpan).getSpanId();
+    }
+    return "0";
+  }
+
+  @Override
+  public boolean addTraceInterceptor(final TraceInterceptor interceptor) {
+    return interceptors.add(interceptor);
+  }
+
   @Override
   public void close() {
     PendingTrace.close();

dd-trace-ot/src/main/java/datadog/opentracing/OTTraceCorrelation.java

@@ -4,14 +4,12 @@ import datadog.trace.common.writer.ListWriter
 import spock.lang.Shared
 import spock.lang.Specification
 
-class OTTraceCorrelationTest extends Specification {
+class TraceCorrelationTest extends Specification {
 
   static final WRITER = new ListWriter()
 
   @Shared
   DDTracer tracer = new DDTracer(WRITER)
-  @Shared
-  OTTraceCorrelation traceCorrelation = new OTTraceCorrelation(tracer)
 
   def scope = tracer.buildSpan("test").startActive(true)
 
@@ -24,24 +22,24 @@ class OTTraceCorrelationTest extends Specification {
     scope.close()
 
     expect:
-    "0" == traceCorrelation.getTraceId()
+    "0" == tracer.getTraceId()
   }
 
   def "get trace id with trace"() {
     expect:
-    ((DDSpan) scope.span()).traceId == traceCorrelation.getTraceId()
+    ((DDSpan) scope.span()).traceId == tracer.getTraceId()
   }
 
   def "get span id without span"() {
     setup:
     scope.close()
 
     expect:
-    "0" == traceCorrelation.getSpanId()
+    "0" == tracer.getSpanId()
   }
 
   def "get span id with trace"() {
     expect:
-    ((DDSpan) scope.span()).spanId == traceCorrelation.getSpanId()
+    ((DDSpan) scope.span()).spanId == tracer.getSpanId()
   }
 }

dd-trace-ot/src/test/groovy/datadog/opentracing/OTTraceCorrelationTest.groovy renamed to dd-trace-ot/src/test/groovy/datadog/opentracing/TraceCorrelationTest.groovy

@@ -3,6 +3,7 @@ package datadog.opentracing
 import datadog.trace.api.interceptor.MutableSpan
 import datadog.trace.api.interceptor.TraceInterceptor
 import datadog.trace.common.writer.ListWriter
+import datadog.trace.api.GlobalTracer
 import spock.lang.Specification
 
 import java.util.concurrent.atomic.AtomicBoolean
@@ -143,4 +144,24 @@ class TraceInterceptorTest extends Specification {
     tags["thread.id"] != null
     tags.size() == 6
   }
+
+  def "register interceptor through bridge" () {
+    setup:
+    GlobalTracer.registerIfAbsent(tracer)
+    def interceptor = new TraceInterceptor() {
+      @Override
+      Collection<? extends MutableSpan> onTraceComplete(Collection<? extends MutableSpan> trace) {
+        return trace
+      }
+
+      @Override
+      int priority() {
+        return 38
+      }
+    }
+
+    expect:
+    GlobalTracer.get().addTraceInterceptor(interceptor)
+    tracer.interceptors.contains(interceptor)
+  }
 }