From 7b0720a3383ac44de83cd780596702fcd2a78c25 Mon Sep 17 00:00:00 2001
From: Carlos Alberto Cortez <calberto.cortez@gmail.com>
Date: Thu, 17 Aug 2017 16:36:59 +0200
Subject: [PATCH] Add an example of nested callbacks.

'Only' put 3 levels of callbacks, to not
make it too hard to read.
---
 .../nested_callbacks/TestNestedCallbacks.java | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 src/test/java/io/opentracing/contrib/examples/nested_callbacks/TestNestedCallbacks.java

diff --git a/src/test/java/io/opentracing/contrib/examples/nested_callbacks/TestNestedCallbacks.java b/src/test/java/io/opentracing/contrib/examples/nested_callbacks/TestNestedCallbacks.java
new file mode 100644
index 0000000..d05a33e
--- /dev/null
+++ b/src/test/java/io/opentracing/contrib/examples/nested_callbacks/TestNestedCallbacks.java
@@ -0,0 +1,77 @@
+package io.opentracing.contrib.examples.nested_callbacks;
+
+import static com.jayway.awaitility.Awaitility.await;
+import static io.opentracing.contrib.examples.TestUtils.reportedSpansSize;
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.junit.Assert.assertEquals;
+
+import io.opentracing.ActiveSpan;
+import io.opentracing.mock.MockSpan;
+import io.opentracing.mock.MockTracer;
+import io.opentracing.mock.MockTracer.Propagator;
+import io.opentracing.util.ThreadLocalActiveSpanSource;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.TimeUnit;
+import org.junit.Test;
+
+public class TestNestedCallbacks {
+
+  private final MockTracer tracer = new MockTracer(new ThreadLocalActiveSpanSource(),
+      Propagator.TEXT_MAP);
+  private final ExecutorService executor = Executors.newCachedThreadPool();
+
+  @Test
+  public void test() throws Exception {
+
+    try (ActiveSpan span = tracer.buildSpan("one").startActive()) {
+      submitCallbacks(span);
+    }
+
+    await().atMost(15, TimeUnit.SECONDS).until(reportedSpansSize(tracer), equalTo(1));
+
+    List<MockSpan> spans = tracer.finishedSpans();
+    assertEquals(1, spans.size());
+    assertEquals("one", spans.get(0).operationName());
+
+    Map<String, Object> tags = spans.get(0).tags();
+    assertEquals(3, tags.size());
+    for (int i = 1; i <= 3; i++)
+      assertEquals(Integer.toString(i), tags.get("key" + i));
+  }
+
+  void submitCallbacks(ActiveSpan span) {
+    final ActiveSpan.Continuation cont = span.capture();
+
+    executor.submit(new Runnable() {
+      @Override
+      public void run() {
+        try (ActiveSpan span = cont.activate()) {
+          span.setTag("key1", "1");
+          final ActiveSpan.Continuation cont = span.capture();
+
+          executor.submit(new Runnable() {
+            @Override
+            public void run() {
+              try (ActiveSpan span = cont.activate()) {
+                span.setTag("key2", "2");
+                final ActiveSpan.Continuation cont = span.capture();
+
+                executor.submit(new Runnable() {
+                  @Override
+                  public void run() {
+                    try (ActiveSpan span = cont.activate()) {
+                      span.setTag("key3", "3");
+                    }
+                  }
+                });
+              }
+            }
+          });
+        }
+      }
+    });
+  }
+}