Merge pull request #826 from HailongWen/noop-span-store

Add NoopRunningSpanStore and NoopSampledSpanStore.

Author: HailongWen

api/src/main/java/io/opencensus/trace/TraceComponent.java

@@ -29,7 +29,6 @@
  * <p>Unless otherwise noted all methods (on component) results are cacheable.
  */
 public abstract class TraceComponent {
-  private static final NoopTraceComponent noopTraceComponent = new NoopTraceComponent();
 
   /**
    * Returns the {@link Tracer} with the provided implementations. If no implementation is provided
@@ -75,11 +74,13 @@ public abstract class TraceComponent {
    *
    * @return an instance that contains no-op implementations for all the instances.
    */
-  static TraceComponent getNoopTraceComponent() {
-    return noopTraceComponent;
+  static TraceComponent newNoopTraceComponent() {
+    return new NoopTraceComponent();
   }
 
   private static final class NoopTraceComponent extends TraceComponent {
+    private final ExportComponent noopExportComponent = ExportComponent.newNoopExportComponent();
+
     @Override
     public Tracer getTracer() {
       return Tracer.getNoopTracer();
@@ -97,7 +98,7 @@ public Clock getClock() {
 
     @Override
     public ExportComponent getExportComponent() {
-      return ExportComponent.getNoopExportComponent();
+      return noopExportComponent;
     }
 
     @Override

api/src/main/java/io/opencensus/trace/Tracing.java

@@ -103,7 +103,7 @@ static TraceComponent loadTraceComponent(ClassLoader classLoader) {
               + "default implementation for TraceComponent.",
           e);
     }
-    return TraceComponent.getNoopTraceComponent();
+    return TraceComponent.newNoopTraceComponent();
   }
 
   // No instance of this class.

api/src/main/java/io/opencensus/trace/export/ExportComponent.java

@@ -17,7 +17,6 @@
 package io.opencensus.trace.export;
 
 import io.opencensus.trace.TraceOptions;
-import javax.annotation.Nullable;
 
 /**
  * Class that holds the implementation instances for {@link SpanExporter}, {@link RunningSpanStore}
@@ -27,15 +26,13 @@
  */
 public abstract class ExportComponent {
 
-  private static final NoopExportComponent NOOP_EXPORT_COMPONENT = new NoopExportComponent();
-
   /**
    * Returns the no-op implementation of the {@code ExportComponent}.
    *
    * @return the no-op implementation of the {@code ExportComponent}.
    */
-  public static ExportComponent getNoopExportComponent() {
-    return NOOP_EXPORT_COMPONENT;
+  public static ExportComponent newNoopExportComponent() {
+    return new NoopExportComponent();
   }
 
   /**
@@ -51,36 +48,35 @@ public static ExportComponent getNoopExportComponent() {
    * Returns the {@link RunningSpanStore} that can be used to get useful debugging information about
    * all the current active spans.
    *
-   * @return the {@code RunningSpanStore} or {@code null} if not supported.
+   * @return the {@code RunningSpanStore}.
    */
-  @Nullable
   public abstract RunningSpanStore getRunningSpanStore();
 
   /**
    * Returns the {@link SampledSpanStore} that can be used to get useful debugging information, such
    * as latency based sampled spans, error based sampled spans.
    *
-   * @return the {@code SampledSpanStore} or {@code null} if not supported.
+   * @return the {@code SampledSpanStore}.
    */
-  @Nullable
   public abstract SampledSpanStore getSampledSpanStore();
 
   private static final class NoopExportComponent extends ExportComponent {
+    private final SampledSpanStore noopSampledSpanStore =
+        SampledSpanStore.newNoopSampledSpanStore();
+
     @Override
     public SpanExporter getSpanExporter() {
       return SpanExporter.getNoopSpanExporter();
     }
 
-    @Nullable
     @Override
     public RunningSpanStore getRunningSpanStore() {
-      return null;
+      return RunningSpanStore.getNoopRunningSpanStore();
     }
 
-    @Nullable
     @Override
     public SampledSpanStore getSampledSpanStore() {
-      return null;
+      return noopSampledSpanStore;
     }
   }
 }

api/src/main/java/io/opencensus/trace/export/RunningSpanStore.java

@@ -37,8 +37,19 @@
 @ThreadSafe
 public abstract class RunningSpanStore {
 
+  private static final RunningSpanStore NOOP_RUNNING_SPAN_STORE = new NoopRunningSpanStore();
+
   protected RunningSpanStore() {}
 
+  /**
+   * Returns the no-op implementation of the {@code RunningSpanStore}.
+   *
+   * @return the no-op implementation of the {@code RunningSpanStore}.
+   */
+  static RunningSpanStore getNoopRunningSpanStore() {
+    return NOOP_RUNNING_SPAN_STORE;
+  }
+
   /**
    * Returns the summary of all available data such, as number of running spans.
    *
@@ -151,4 +162,21 @@ public static Filter create(String spanName, int maxSpansToReturn) {
      */
     public abstract int getMaxSpansToReturn();
   }
+
+  private static final class NoopRunningSpanStore extends RunningSpanStore {
+
+    private static final Summary EMPTY_SUMMARY =
+        Summary.create(Collections.<String, PerSpanNameSummary>emptyMap());
+
+    @Override
+    public Summary getSummary() {
+      return EMPTY_SUMMARY;
+    }
+
+    @Override
+    public Collection<SpanData> getRunningSpans(Filter filter) {
+      checkNotNull(filter, "filter");
+      return Collections.<SpanData>emptyList();
+    }
+  }
 }

api/src/main/java/io/opencensus/trace/export/SampledSpanStore.java

@@ -21,6 +21,8 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
 import io.opencensus.trace.Span;
 import io.opencensus.trace.Status;
 import io.opencensus.trace.Status.CanonicalCode;
@@ -31,6 +33,7 @@
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.Immutable;
 import javax.annotation.concurrent.ThreadSafe;
 
@@ -48,6 +51,17 @@ public abstract class SampledSpanStore {
 
   protected SampledSpanStore() {}
 
+  /**
+   * Returns a {@code SampledSpanStore} that maintains a set of span names, but always returns an
+   * empty list of {@link SpanData}.
+   *
+   * @return a {@code SampledSpanStore} that maintains a set of span names, but always returns an
+   *     empty list of {@code SpanData}.
+   */
+  static SampledSpanStore newNoopSampledSpanStore() {
+    return new NoopSampledSpanStore();
+  }
+
   /**
    * Returns the summary of all available data, such as number of sampled spans in the latency based
    * samples or error based samples.
@@ -370,4 +384,61 @@ public static ErrorFilter create(
      */
     public abstract int getMaxSpansToReturn();
   }
+
+  @ThreadSafe
+  private static final class NoopSampledSpanStore extends SampledSpanStore {
+    private static final PerSpanNameSummary EMPTY_PER_SPAN_NAME_SUMMARY =
+        PerSpanNameSummary.create(
+            Collections.<SampledSpanStore.LatencyBucketBoundaries, Integer>emptyMap(),
+            Collections.<CanonicalCode, Integer>emptyMap());
+
+    @GuardedBy("registeredSpanNames")
+    private final Set<String> registeredSpanNames = Sets.newHashSet();
+
+    @Override
+    public Summary getSummary() {
+      Map<String, PerSpanNameSummary> result = Maps.newHashMap();
+      synchronized (registeredSpanNames) {
+        for (String registeredSpanName : registeredSpanNames) {
+          result.put(registeredSpanName, EMPTY_PER_SPAN_NAME_SUMMARY);
+        }
+      }
+      return Summary.create(result);
+    }
+
+    @Override
+    public Collection<SpanData> getLatencySampledSpans(LatencyFilter filter) {
+      checkNotNull(filter, "latencyFilter");
+      return Collections.<SpanData>emptyList();
+    }
+
+    @Override
+    public Collection<SpanData> getErrorSampledSpans(ErrorFilter filter) {
+      checkNotNull(filter, "errorFilter");
+      return Collections.<SpanData>emptyList();
+    }
+
+    @Override
+    public void registerSpanNamesForCollection(Collection<String> spanNames) {
+      checkNotNull(spanNames, "spanNames");
+      synchronized (registeredSpanNames) {
+        registeredSpanNames.addAll(spanNames);
+      }
+    }
+
+    @Override
+    public void unregisterSpanNamesForCollection(Collection<String> spanNames) {
+      checkNotNull(spanNames);
+      synchronized (registeredSpanNames) {
+        registeredSpanNames.removeAll(spanNames);
+      }
+    }
+
+    @Override
+    public Set<String> getRegisteredSpanNamesForCollection() {
+      synchronized (registeredSpanNames) {
+        return Collections.<String>unmodifiableSet(Sets.newHashSet(registeredSpanNames));
+      }
+    }
+  }
 }

api/src/test/java/io/opencensus/trace/TraceComponentTest.java

@@ -31,29 +31,29 @@
 public class TraceComponentTest {
   @Test
   public void defaultTracer() {
-    assertThat(TraceComponent.getNoopTraceComponent().getTracer()).isSameAs(Tracer.getNoopTracer());
+    assertThat(TraceComponent.newNoopTraceComponent().getTracer()).isSameAs(Tracer.getNoopTracer());
   }
 
   @Test
   public void defaultBinaryPropagationHandler() {
-    assertThat(TraceComponent.getNoopTraceComponent().getPropagationComponent())
+    assertThat(TraceComponent.newNoopTraceComponent().getPropagationComponent())
         .isSameAs(PropagationComponent.getNoopPropagationComponent());
   }
 
   @Test
   public void defaultClock() {
-    assertThat(TraceComponent.getNoopTraceComponent().getClock()).isInstanceOf(ZeroTimeClock.class);
+    assertThat(TraceComponent.newNoopTraceComponent().getClock()).isInstanceOf(ZeroTimeClock.class);
   }
 
   @Test
   public void defaultTraceExporter() {
-    assertThat(TraceComponent.getNoopTraceComponent().getExportComponent())
-        .isSameAs(ExportComponent.getNoopExportComponent());
+    assertThat(TraceComponent.newNoopTraceComponent().getExportComponent())
+        .isInstanceOf(ExportComponent.newNoopExportComponent().getClass());
   }
 
   @Test
   public void defaultTraceConfig() {
-    assertThat(TraceComponent.getNoopTraceComponent().getTraceConfig())
+    assertThat(TraceComponent.newNoopTraceComponent().getTraceConfig())
         .isSameAs(TraceConfig.getNoopTraceConfig());
   }
 }

api/src/test/java/io/opencensus/trace/TracingTest.java

@@ -72,7 +72,8 @@ public void defaultBinaryPropagationHandler() {
 
   @Test
   public void defaultTraceExporter() {
-    assertThat(Tracing.getExportComponent()).isSameAs(ExportComponent.getNoopExportComponent());
+    assertThat(Tracing.getExportComponent())
+        .isInstanceOf(ExportComponent.newNoopExportComponent().getClass());
   }
 
   @Test

api/src/test/java/io/opencensus/trace/export/ExportComponentTest.java

@@ -25,7 +25,7 @@
 /** Unit tests for {@link ExportComponent}. */
 @RunWith(JUnit4.class)
 public class ExportComponentTest {
-  private final ExportComponent exportComponent = ExportComponent.getNoopExportComponent();
+  private final ExportComponent exportComponent = ExportComponent.newNoopExportComponent();
 
   @Test
   public void implementationOfSpanExporter() {
@@ -34,11 +34,13 @@ public void implementationOfSpanExporter() {
 
   @Test
   public void implementationOfActiveSpans() {
-    assertThat(exportComponent.getRunningSpanStore()).isNull();
+    assertThat(exportComponent.getRunningSpanStore())
+        .isEqualTo(RunningSpanStore.getNoopRunningSpanStore());
   }
 
   @Test
   public void implementationOfSampledSpanStore() {
-    assertThat(exportComponent.getSampledSpanStore()).isNull();
+    assertThat(exportComponent.getSampledSpanStore())
+        .isInstanceOf(SampledSpanStore.newNoopSampledSpanStore().getClass());
   }
 }

api/src/test/java/io/opencensus/trace/export/NoopRunningSpanStoreTest.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2017, OpenCensus Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.opencensus.trace.export;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.util.Collection;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link NoopRunningSpanStore}. */
+@RunWith(JUnit4.class)
+public final class NoopRunningSpanStoreTest {
+
+  private final RunningSpanStore runningSpanStore =
+      ExportComponent.newNoopExportComponent().getRunningSpanStore();
+
+  @Rule public final ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void noopRunningSpanStore_GetSummary() {
+    RunningSpanStore.Summary summary = runningSpanStore.getSummary();
+    assertThat(summary.getPerSpanNameSummary()).isEmpty();
+  }
+
+  @Test
+  public void noopRunningSpanStore_GetRunningSpans_DisallowsNull() {
+    thrown.expect(NullPointerException.class);
+    runningSpanStore.getRunningSpans(null);
+  }
+
+  @Test
+  public void noopRunningSpanStore_GetRunningSpans() {
+    Collection<SpanData> runningSpans =
+        runningSpanStore.getRunningSpans(RunningSpanStore.Filter.create("TestSpan", 0));
+    assertThat(runningSpans).isEmpty();
+  }
+}