Provide ignore mechanism for TracerContext.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/ContextManager.java

@@ -86,7 +86,7 @@ public class ContextManager implements TracerContextListener, BootService, Ignor
     @Override
     public void bootUp() {
         TracerContext.ListenerManager.add(this);
-        IgnoreTracerContext.ListenerManager.add(this);
+        IgnoredTracerContext.ListenerManager.add(this);
     }
 
     @Override
@@ -95,7 +95,7 @@ public class ContextManager implements TracerContextListener, BootService, Ignor
     }
 
     @Override
-    public void afterFinished(IgnoreTracerContext traceSegment) {
+    public void afterFinished(IgnoredTracerContext traceSegment) {
         CONTEXT.remove();
     }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/IgnoreTracerContextListener.java

@@ -5,5 +5,5 @@ package org.skywalking.apm.agent.core.context;
  * @author wusheng
  */
 public interface IgnoreTracerContextListener {
-    void afterFinished(IgnoreTracerContext traceSegment);
+    void afterFinished(IgnoredTracerContext traceSegment);
 }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/IgnoreTracerContext.java → apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/IgnoredTracerContext.java

@@ -3,20 +3,21 @@ package org.skywalking.apm.agent.core.context;
 import java.util.LinkedList;
 import java.util.List;
 import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.NoopSpan;
 
 /**
- * The <code>IgnoreTracerContext</code> represent a context should be ignored.
+ * The <code>IgnoredTracerContext</code> represent a context should be ignored.
  * So it just maintains the stack with integer depth.
- * All operations through this <code>IgnoreTracerContext</code> will be ignored, with low gc cost.
- *
- * TODO: Can't return null span
+ * All operations through this <code>IgnoredTracerContext</code> will be ignored, with low gc cost.
  *
  * @author wusheng
  */
-public class IgnoreTracerContext implements AbstractTracerContext {
+public class IgnoredTracerContext implements AbstractTracerContext {
+    private static final NoopSpan NOOP_SPAN = new NoopSpan();
+
     private int stackDepth;
 
-    public IgnoreTracerContext(int initStackDepth) {
+    public IgnoredTracerContext(int initStackDepth) {
         this.stackDepth = initStackDepth;
     }
 
@@ -38,7 +39,7 @@ public class IgnoreTracerContext implements AbstractTracerContext {
     @Override
     public AbstractSpan createSpan(String operationName, boolean isLeaf) {
         stackDepth++;
-        return null;
+        return NOOP_SPAN;
     }
 
     @Override
@@ -48,14 +49,14 @@ public class IgnoreTracerContext implements AbstractTracerContext {
 
     @Override
     public AbstractSpan activeSpan() {
-        return null;
+        return NOOP_SPAN;
     }
 
     @Override
     public void stopSpan(AbstractSpan span) {
         stackDepth--;
         if (stackDepth == 0) {
-
+            ListenerManager.notifyFinish(this);
         }
     }
 
@@ -82,15 +83,15 @@ public class IgnoreTracerContext implements AbstractTracerContext {
         }
 
         /**
-         * Notify the {@link IgnoreTracerContext.ListenerManager} about the given {@link IgnoreTracerContext} have
-         * finished. And trigger {@link IgnoreTracerContext.ListenerManager} to notify all {@link #LISTENERS} 's {@link
-         * IgnoreTracerContextListener#afterFinished(IgnoreTracerContext)}
+         * Notify the {@link IgnoredTracerContext.ListenerManager} about the given {@link IgnoredTracerContext} have
+         * finished. And trigger {@link IgnoredTracerContext.ListenerManager} to notify all {@link #LISTENERS} 's {@link
+         * IgnoreTracerContextListener#afterFinished(IgnoredTracerContext)}
          *
-         * @param ignoreTracerContext
+         * @param ignoredTracerContext
          */
-        static void notifyFinish(IgnoreTracerContext ignoreTracerContext) {
+        static void notifyFinish(IgnoredTracerContext ignoredTracerContext) {
             for (IgnoreTracerContextListener listener : LISTENERS) {
-                listener.afterFinished(ignoreTracerContext);
+                listener.afterFinished(ignoredTracerContext);
             }
         }
 

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/TracerContext.java

@@ -59,6 +59,14 @@ public final class TracerContext implements AbstractTracerContext {
         Span parentSpan = peek();
         Span span;
         if (parentSpan == null) {
+            if (operationName != null) {
+                int suffixIdx = operationName.lastIndexOf(".");
+                if (suffixIdx > -1 && Config.Agent.IGNORE_SUFFIX.contains(operationName.substring(suffixIdx))) {
+                    ContextManager.ContextSwitcher.INSTANCE.toNew(new IgnoredTracerContext(1));
+                    return ContextManager.activeSpan();
+                }
+            }
+
             if (isLeaf) {
                 span = new LeafSpan(spanIdGenerator++, operationName, startTime);
             } else {

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/NoopSpan.java

+package org.skywalking.apm.agent.core.context.trace;
+
+import java.util.Map;
+import org.skywalking.apm.agent.core.context.IgnoredTracerContext;
+
+/**
+ * The <code>NoopSpan</code> represents a span implementation without any actual operation.
+ * This span implementation is for {@link IgnoredTracerContext}.
+ *
+ * @author wusheng
+ */
+public class NoopSpan implements AbstractSpan {
+    @Override
+    public AbstractSpan setOperationName(String operationName) {
+        return this;
+    }
+
+    @Override
+    public void setPeerHost(String peerHost) {
+
+    }
+
+    @Override
+    public void setPort(int port) {
+
+    }
+
+    @Override
+    public void setPeers(String peers) {
+
+    }
+
+    @Override
+    public AbstractSpan setTag(String key, String value) {
+        return this;
+    }
+
+    @Override
+    public AbstractSpan setTag(String key, boolean value) {
+        return this;
+    }
+
+    @Override
+    public AbstractSpan setTag(String key, Integer value) {
+        return this;
+    }
+
+    @Override
+    public AbstractSpan log(Map<String, String> fields) {
+        return this;
+    }
+
+    @Override
+    public AbstractSpan log(Throwable t) {
+        return this;
+    }
+
+    @Override
+    public AbstractSpan log(String event) {
+        return this;
+    }
+
+}

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/Span.java

@@ -13,9 +13,6 @@ import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
-import org.skywalking.apm.agent.core.conf.Config;
-import org.skywalking.apm.agent.core.context.ContextManager;
-import org.skywalking.apm.agent.core.context.IgnoreTracerContext;
 import org.skywalking.apm.agent.core.context.tag.BooleanTagItem;
 import org.skywalking.apm.agent.core.context.tag.IntTagItem;
 import org.skywalking.apm.agent.core.context.tag.StringTagItem;
@@ -191,22 +188,12 @@ public class Span implements AbstractSpan {
     }
 
     /**
-     * Sets the string name for the logical operation this span represents.
-     * These is one scenario, which trigger context switch.
-     * 1) the operations ends with the defined suffix, see {@link Config.Agent#IGNORE_SUFFIX}
+     * Set the string name for the logical operation this span represents.
      *
      * @return this Span instance, for chaining
      */
     public AbstractSpan setOperationName(String operationName) {
         this.operationName = operationName;
-        if (this.spanId == 0) {
-            if (operationName != null) {
-                int suffixIdx = operationName.lastIndexOf(".");
-                if (suffixIdx > -1 && Config.Agent.IGNORE_SUFFIX.contains(operationName.substring(suffixIdx))) {
-                    ContextManager.ContextSwitcher.INSTANCE.toNew(new IgnoreTracerContext(1));
-                }
-            }
-        }
         return this;
     }
 

apm-sniffer/apm-agent-core/src/test/java/org/skywalking/apm/agent/core/context/ContextManagerTestCase.java

 package org.skywalking.apm.agent.core.context;
 
+import java.lang.reflect.Field;
 import org.junit.After;
 import org.junit.Assert;
 import org.junit.BeforeClass;
@@ -7,6 +8,7 @@ import org.junit.Test;
 import org.skywalking.apm.agent.core.boot.ServiceManager;
 import org.skywalking.apm.agent.core.context.tag.Tags;
 import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
+import org.skywalking.apm.agent.core.context.trace.NoopSpan;
 import org.skywalking.apm.agent.core.context.trace.TraceSegment;
 
 /**
@@ -33,6 +35,35 @@ public class ContextManagerTestCase {
         Assert.assertEquals(span, segment.getSpans().get(0));
     }
 
+    @Test
+    public void testSwitchToIgnoredTracerContext() throws NoSuchFieldException, IllegalAccessException {
+        AbstractSpan span = ContextManager.createSpan("/webresource/jquery.js");
+        Tags.COMPONENT.set(span, "test");
+
+        Assert.assertTrue(span instanceof NoopSpan);
+        Assert.assertTrue(ContextManager.activeSpan() instanceof NoopSpan);
+
+        Field context = ContextManager.class.getDeclaredField("CONTEXT");
+        context.setAccessible(true);
+        AbstractTracerContext tracerContext = ((ThreadLocal<AbstractTracerContext>)context.get(null)).get();
+
+        Assert.assertTrue(tracerContext instanceof IgnoredTracerContext);
+
+        ContextManager.stopSpan();
+        tracerContext = ((ThreadLocal<AbstractTracerContext>)context.get(null)).get();
+        Assert.assertNull(tracerContext);
+
+        // check normal trace again
+        span = ContextManager.createSpan("serviceA");
+        Tags.COMPONENT.set(span, "test");
+
+        tracerContext = ((ThreadLocal<AbstractTracerContext>)context.get(null)).get();
+        Assert.assertTrue(tracerContext instanceof TracerContext);
+        ContextManager.stopSpan();
+        tracerContext = ((ThreadLocal<AbstractTracerContext>)context.get(null)).get();
+        Assert.assertNull(tracerContext);
+    }
+
     @After
     public void reset() {
         TracerContext.ListenerManager.remove(TestTracerContextListener.INSTANCE);