zPages: zPages tracez basic example (open-telemetry#268)

examples/zpages/BUILD

@@ -0,0 +1,31 @@
+# Copyright 2020, OpenTelemetry 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(default_visibility = ["//visibility:public"])
+
+cc_binary(
+    name = "zpages_example",
+    srcs = [
+        "zpages_example.cc",
+    ],
+    linkopts = select({
+        "//bazel:windows": [],
+        "//conditions:default": ["-pthread"],
+    }),
+    deps = [
+        "//ext:headers",
+        "//ext/src/zpages",
+        "//sdk/src/trace",
+    ],
+)

examples/zpages/zpages_example.cc

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+/**
+ * This is a basic example for zpages that helps users get familiar with how to
+ * use this feature in OpenTelemetery
+ */
+#include <chrono>
+#include <iostream>
+#include <string>
+#include "opentelemetry/context/threadlocal_context.h"
+
+#include "opentelemetry/ext/zpages/zpages.h"  // Required file include for zpages
+
+using opentelemetry::core::SteadyTimestamp;
+
+int main(int argc, char *argv[])
+{
+
+  /**
+   * The following line initializes zPages and starts a webserver at
+   * http://localhost:30000/tracez/ where spans that are created in the application
+   * can be viewed.
+   * Note that the webserver is destroyed after the application ends execution.
+   */
+  ZPages::Initialize();
+  auto tracer = opentelemetry::trace::Provider::GetTracerProvider()->GetTracer("");
+
+  std::cout << "This example for zPages creates a few types of spans and then "
+            << "creates a span every second for the duration of the application"
+            << "\n";
+
+  // Error span
+  std::map<std::string, opentelemetry::common::AttributeValue> attribute_map;
+  attribute_map["completed_search_for"] = "Unknown user";
+  tracer->StartSpan("find user", attribute_map)
+      ->SetStatus(opentelemetry::trace::CanonicalCode::NOT_FOUND, "User not found");
+
+  // Long time duration span
+  std::map<std::string, opentelemetry::common::AttributeValue> attribute_map2;
+  attribute_map2["completed_search_for"] = "John Doe";
+  opentelemetry::trace::StartSpanOptions start;
+  start.start_steady_time = SteadyTimestamp(nanoseconds(1));
+  opentelemetry::trace::EndSpanOptions end;
+  end.end_steady_time = SteadyTimestamp(nanoseconds(1000000000000));
+  tracer->StartSpan("find user", attribute_map2, start)->End(end);
+
+  // Running(deadlock) span
+  std::map<std::string, opentelemetry::common::AttributeValue> attribute_map3;
+  attribute_map3["searching_for"] = "Deleted user";
+  auto running_span               = tracer->StartSpan("find user", attribute_map3);
+
+  // Create a completed span every second till user stops the loop
+  std::cout << "Presss CTRL+C to stop...\n";
+  while (true)
+  {
+    std::this_thread::sleep_for(seconds(1));
+    tracer->StartSpan("ping user")->End();
+  }
+}