1 files changed, 71 insertions, 0 deletions
diff --git a/impl_core/src/main/java/io/opencensus/implcore/trace/export/RunningSpanStoreImpl.java b/impl_core/src/main/java/io/opencensus/implcore/trace/export/RunningSpanStoreImpl.java
new file mode 100644
index 00000000..962f5b01
--- /dev/null
+++ b/impl_core/src/main/java/io/opencensus/implcore/trace/export/RunningSpanStoreImpl.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018, 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.implcore.trace.export;
+
+import io.opencensus.implcore.trace.RecordEventsSpanImpl;
+import io.opencensus.trace.export.RunningSpanStore;
+import io.opencensus.trace.export.SpanData;
+import java.util.Collection;
+import java.util.Collections;
+
+/** Abstract implementation of the {@link RunningSpanStore}. */
+public abstract class RunningSpanStoreImpl extends RunningSpanStore {
+
+  private static final RunningSpanStoreImpl NOOP_RUNNING_SPAN_STORE_IMPL =
+      new NoopRunningSpanStoreImpl();
+
+  /** Returns the no-op implementation of the {@link RunningSpanStoreImpl}. */
+  static RunningSpanStoreImpl getNoopRunningSpanStoreImpl() {
+    return NOOP_RUNNING_SPAN_STORE_IMPL;
+  }
+
+  /**
+   * Adds the {@code Span} into the running spans list when the {@code Span} starts.
+   *
+   * @param span the {@code Span} that started.
+   */
+  public abstract void onStart(RecordEventsSpanImpl span);
+
+  /**
+   * Removes the {@code Span} from the running spans list when the {@code Span} ends.
+   *
+   * @param span the {@code Span} that ended.
+   */
+  public abstract void onEnd(RecordEventsSpanImpl span);
+
+  private static final class NoopRunningSpanStoreImpl extends RunningSpanStoreImpl {
+
+    private static final Summary EMPTY_SUMMARY =
+        RunningSpanStore.Summary.create(Collections.<String, PerSpanNameSummary>emptyMap());
+
+    @Override
+    public void onStart(RecordEventsSpanImpl span) {}
+
+    @Override
+    public void onEnd(RecordEventsSpanImpl span) {}
+
+    @Override
+    public Summary getSummary() {
+      return EMPTY_SUMMARY;
+    }
+
+    @Override
+    public Collection<SpanData> getRunningSpans(Filter filter) {
+      return Collections.<SpanData>emptyList();
+    }
+  }
+}