Add example for Logs ostream exporter (#1992)

Author: MrSparc

examples/CMakeLists.txt

@@ -21,6 +21,9 @@ endif()
 if(WITH_PROMETHEUS)
   add_subdirectory(prometheus)
 endif()
+if(WITH_LOGS_PREVIEW)
+  add_subdirectory(logs_simple)
+endif()
 add_subdirectory(plugin)
 add_subdirectory(simple)
 add_subdirectory(batch)

examples/logs_simple/BUILD

@@ -0,0 +1,19 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+cc_binary(
+    name = "example_logs_simple",
+    srcs = [
+        "main.cc",
+    ],
+    tags = [
+        "examples",
+        "ostream",
+    ],
+    deps = [
+        "//api",
+        "//examples/common/logs_foo_library:common_logs_foo_library",
+        "//exporters/ostream:ostream_log_record_exporter",
+        "//exporters/ostream:ostream_span_exporter",
+    ],
+)

examples/logs_simple/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+if(DEFINED OPENTELEMETRY_BUILD_DLL)
+  add_definitions(-DOPENTELEMETRY_BUILD_IMPORT_DLL)
+endif()
+
+include_directories(${CMAKE_SOURCE_DIR}/exporters/ostream/include)
+
+if(WITH_LOGS_PREVIEW)
+  add_executable(example_logs_simple main.cc)
+  target_link_libraries(example_logs_simple ${CMAKE_THREAD_LIBS_INIT}
+                        common_logs_foo_library)
+
+  if(DEFINED OPENTELEMETRY_BUILD_DLL)
+    target_link_libraries(example_logs_simple opentelemetry_cpp)
+  else()
+    target_link_libraries(
+      example_logs_simple opentelemetry_trace opentelemetry_logs
+      opentelemetry_exporter_ostream_span opentelemetry_exporter_ostream_logs)
+  endif()
+endif()

examples/logs_simple/README.md

@@ -0,0 +1,16 @@
+
+# Simple Logs Example
+
+In this example, the application in `main.cc` initializes an
+`OStreamLogRecordExporter` instance and registers a logger
+provider, as well as initializes a `StdoutSpanExporter` instance and registers a
+tracer provider from the [OpenTelemetry
+SDK](https://github.com/open-telemetry/opentelemetry-cpp).
+
+The application then calls a `logs_foo_library` which has been instrumented
+using the [OpenTelemetry
+API](https://github.com/open-telemetry/opentelemetry-cpp/tree/main/api).
+Resulting logs and traces are directed to stdout.
+
+See [CONTRIBUTING.md](../../CONTRIBUTING.md) for instructions on building and
+running the example.

examples/logs_simple/main.cc

@@ -0,0 +1,83 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#ifdef ENABLE_LOGS_PREVIEW
+#  include "opentelemetry/exporters/ostream/span_exporter_factory.h"
+#  include "opentelemetry/sdk/trace/simple_processor_factory.h"
+#  include "opentelemetry/sdk/trace/tracer_provider_factory.h"
+#  include "opentelemetry/trace/provider.h"
+
+#  include "opentelemetry/exporters/ostream/log_record_exporter.h"
+#  include "opentelemetry/logs/provider.h"
+#  include "opentelemetry/sdk/logs/logger_provider_factory.h"
+#  include "opentelemetry/sdk/logs/simple_log_record_processor_factory.h"
+
+#  ifdef BAZEL_BUILD
+#    include "examples/common/logs_foo_library/foo_library.h"
+#  else
+#    include "logs_foo_library/foo_library.h"
+#  endif
+
+namespace logs_api      = opentelemetry::logs;
+namespace logs_sdk      = opentelemetry::sdk::logs;
+namespace logs_exporter = opentelemetry::exporter::logs;
+
+namespace trace_api      = opentelemetry::trace;
+namespace trace_sdk      = opentelemetry::sdk::trace;
+namespace trace_exporter = opentelemetry::exporter::trace;
+
+namespace
+{
+void InitTracer()
+{
+  // Create ostream span exporter instance
+  auto exporter  = trace_exporter::OStreamSpanExporterFactory::Create();
+  auto processor = trace_sdk::SimpleSpanProcessorFactory::Create(std::move(exporter));
+  std::shared_ptr<trace_api::TracerProvider> provider =
+      trace_sdk::TracerProviderFactory::Create(std::move(processor));
+
+  // Set the global trace provider
+  trace_api::Provider::SetTracerProvider(provider);
+}
+
+void CleanupTracer()
+{
+  std::shared_ptr<trace_api::TracerProvider> none;
+  trace_api::Provider::SetTracerProvider(none);
+}
+
+void InitLogger()
+{
+  // Create ostream log exporter instance
+  auto exporter =
+      std::unique_ptr<logs_sdk::LogRecordExporter>(new logs_exporter::OStreamLogRecordExporter);
+  auto processor = logs_sdk::SimpleLogRecordProcessorFactory::Create(std::move(exporter));
+  std::shared_ptr<logs_api::LoggerProvider> provider(
+      logs_sdk::LoggerProviderFactory::Create(std::move(processor)));
+
+  // Set the global logger provider
+  logs_api::Provider::SetLoggerProvider(provider);
+}
+
+void CleanupLogger()
+{
+  std::shared_ptr<logs_api::LoggerProvider> none;
+  logs_api::Provider::SetLoggerProvider(none);
+}
+
+}  // namespace
+
+int main()
+{
+  InitTracer();
+  InitLogger();
+  foo_library();
+  CleanupTracer();
+  CleanupLogger();
+}
+#else
+int main()
+{
+  return 0;
+}
+#endif  // ENABLE_LOGS_PREVIEW