[TEST] Expand api singleton test to cover explicit dlopen().

api/test/singleton/BUILD

@@ -117,11 +117,60 @@ cc_library(
     ],
 )
 
+# no cc_shared_library in bazel 4.2
+cc_binary(
+    name = "component_g",
+    srcs = [
+        "component_g.cc",
+    ],
+    copts = select({
+        "//bazel:windows": DEFAULT_WIN_COPTS,
+        "//conditions:default": DEFAULT_NOWIN_COPTS,
+    }),
+    linkshared = True,
+    deps = [
+        "//api",
+    ],
+)
+
+# no cc_shared_library in bazel 4.2
+cc_binary(
+    name = "component_h",
+    srcs = [
+        "component_h.cc",
+    ],
+    copts = select({
+        "//bazel:windows": HIDDEN_WIN_COPTS,
+        "//conditions:default": HIDDEN_NOWIN_COPTS,
+    }),
+    linkshared = True,
+    deps = [
+        "//api",
+    ],
+)
+
+#
+# To build this test alone:
+# - bazel build //api/test/singleton:singleton_test
+# - bazel build //api/test/singleton:component_g
+# - bazel build //api/test/singleton:component_h
+#
+# Note that singleton_test does not depend on
+# component_g and component_h, on purpose.
+#
+# To run this test:
+# bazel test //api/test/singleton:singleton_test
+#
+
 cc_test(
     name = "singleton_test",
     srcs = [
         "singleton_test.cc",
     ],
+    defines = ["BAZEL_BUILD"],
+    linkopts = [
+        "-ldl",
+    ],
     linkstatic = False,
     tags = [
         "api",

api/test/singleton/CMakeLists.txt

@@ -29,8 +29,17 @@ if(NOT WIN32)
   set_target_properties(component_f PROPERTIES CXX_VISIBILITY_PRESET hidden)
   target_link_libraries(component_f opentelemetry_api)
 
+  add_library(component_g SHARED component_g.cc)
+  set_target_properties(component_g PROPERTIES CXX_VISIBILITY_PRESET default)
+  target_link_libraries(component_g opentelemetry_api)
+
+  add_library(component_h SHARED component_h.cc)
+  set_target_properties(component_h PROPERTIES CXX_VISIBILITY_PRESET hidden)
+  target_link_libraries(component_h opentelemetry_api)
+
   add_executable(singleton_test singleton_test.cc)
 
+  # Not linking with component_g and component_h on purpose
   target_link_libraries(
     singleton_test
     component_a
@@ -41,6 +50,7 @@ if(NOT WIN32)
     component_f
     ${GTEST_BOTH_LIBRARIES}
     ${CMAKE_THREAD_LIBS_INIT}
+    ${CMAKE_DL_LIBS}
     opentelemetry_api)
 
   gtest_add_tests(

api/test/singleton/component_c.h

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #if defined(_MSC_VER)
-// component_c is a DDL
+// component_c is a DLL
 
 #  ifdef BUILD_COMPONENT_C
 __declspec(dllexport)

api/test/singleton/component_d.h

@@ -4,7 +4,7 @@
 // Make the entry point visible, loaded dynamically
 
 #if defined(_MSC_VER)
-// component_d is a DDL
+// component_d is a DLL
 
 #  ifdef BUILD_COMPONENT_D
 __declspec(dllexport)

api/test/singleton/component_e.h

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #if defined(_MSC_VER)
-// component_e is a DDL
+// component_e is a DLL
 
 #  ifdef BUILD_COMPONENT_E
 __declspec(dllexport)

api/test/singleton/component_f.h

@@ -4,7 +4,7 @@
 // Make the entry point visible, loaded dynamically
 
 #if defined(_MSC_VER)
-// component_f is a DDL
+// component_f is a DLL
 
 #  ifdef BUILD_COMPONENT_F
 __declspec(dllexport)

api/test/singleton/component_g.cc

@@ -0,0 +1,42 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "opentelemetry/nostd/shared_ptr.h"
+#include "opentelemetry/trace/provider.h"
+#include "opentelemetry/version.h"
+
+namespace trace = opentelemetry::trace;
+namespace nostd = opentelemetry::nostd;
+
+static nostd::shared_ptr<trace::Tracer> get_tracer()
+{
+  auto provider = trace::Provider::GetTracerProvider();
+  return provider->GetTracer("G", "70.7");
+}
+
+static void f1()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("G::f1"));
+}
+
+static void f2()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("G::f2"));
+
+  f1();
+  f1();
+}
+
+extern "C"
+
+#if defined(_MSC_VER)
+    // component_g is a DLL
+    __declspec(dllexport)
+#endif
+
+        void do_something_in_g()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("G::library"));
+
+  f2();
+}

api/test/singleton/component_h.cc

@@ -0,0 +1,48 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "opentelemetry/nostd/shared_ptr.h"
+#include "opentelemetry/trace/provider.h"
+#include "opentelemetry/version.h"
+
+namespace trace = opentelemetry::trace;
+namespace nostd = opentelemetry::nostd;
+
+static nostd::shared_ptr<trace::Tracer> get_tracer()
+{
+  auto provider = trace::Provider::GetTracerProvider();
+  return provider->GetTracer("H", "80.8");
+}
+
+static void f1()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("H::f1"));
+}
+
+static void f2()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("H::f2"));
+
+  f1();
+  f1();
+}
+
+extern "C"
+
+#if defined(_MSC_VER)
+    // component_h is a DLL
+
+    __declspec(dllexport)
+
+#else
+// component_h is a shared library (*.so)
+// component_h is compiled with visibility("hidden"),
+__attribute__((visibility("default")))
+#endif
+
+        void do_something_in_h()
+{
+  auto scoped_span = trace::Scope(get_tracer()->StartSpan("H::library"));
+
+  f2();
+}

api/test/singleton/singleton_test.cc

@@ -3,7 +3,15 @@
 
 #include <gtest/gtest.h>
 
-#include <assert.h>
+/*
+  TODO:
+  Once singleton are supported for windows,
+  expand this test to use ::LoadLibrary, ::GetProcAddress, ::FreeLibrary
+*/
+#ifndef _WIN32
+#  include <dlfcn.h>
+#endif
+
 #include <iostream>
 
 #include "component_a.h"
@@ -30,6 +38,42 @@ void do_something()
   do_something_in_d();
   do_something_in_e();
   do_something_in_f();
+
+  /*
+    See https://github.com/bazelbuild/bazel/issues/4218
+
+    There is no way to set LD_LIBRARY_PATH in bazel,
+    for dlopen() to find the library.
+
+    Verified manually that dlopen("/full/path/to/libcomponent_g.so") works,
+    and that the test passes in this case.
+  */
+
+#ifndef BAZEL_BUILD
+  /* Call do_something_in_g() */
+
+  void *component_g = dlopen("libcomponent_g.so", RTLD_NOW);
+  EXPECT_NE(component_g, nullptr);
+
+  auto *func_g = (void (*)())dlsym(component_g, "do_something_in_g");
+  EXPECT_NE(func_g, nullptr);
+
+  (*func_g)();
+
+  dlclose(component_g);
+
+  /* Call do_something_in_h() */
+
+  void *component_h = dlopen("libcomponent_h.so", RTLD_NOW);
+  EXPECT_NE(component_h, nullptr);
+
+  auto *func_h = (void (*)())dlsym(component_h, "do_something_in_h");
+  EXPECT_NE(func_h, nullptr);
+
+  (*func_h)();
+
+  dlclose(component_h);
+#endif
 }
 
 int span_a_lib_count   = 0;
@@ -50,6 +94,12 @@ int span_e_f2_count    = 0;
 int span_f_lib_count   = 0;
 int span_f_f1_count    = 0;
 int span_f_f2_count    = 0;
+int span_g_lib_count   = 0;
+int span_g_f1_count    = 0;
+int span_g_f2_count    = 0;
+int span_h_lib_count   = 0;
+int span_h_f1_count    = 0;
+int span_h_f2_count    = 0;
 int unknown_span_count = 0;
 
 void reset_counts()
@@ -72,6 +122,12 @@ void reset_counts()
   span_f_lib_count   = 0;
   span_f_f1_count    = 0;
   span_f_f2_count    = 0;
+  span_g_lib_count   = 0;
+  span_g_f1_count    = 0;
+  span_g_f2_count    = 0;
+  span_h_lib_count   = 0;
+  span_h_f1_count    = 0;
+  span_h_f2_count    = 0;
   unknown_span_count = 0;
 }
 
@@ -162,6 +218,30 @@ class MyTracer : public trace::Tracer
     {
       span_f_f2_count++;
     }
+    else if (name == "G::library")
+    {
+      span_g_lib_count++;
+    }
+    else if (name == "G::f1")
+    {
+      span_g_f1_count++;
+    }
+    else if (name == "G::f2")
+    {
+      span_g_f2_count++;
+    }
+    else if (name == "H::library")
+    {
+      span_h_lib_count++;
+    }
+    else if (name == "H::f1")
+    {
+      span_h_f1_count++;
+    }
+    else if (name == "H::f2")
+    {
+      span_h_f2_count++;
+    }
     else
     {
       unknown_span_count++;
@@ -236,6 +316,12 @@ TEST(SingletonTest, Uniqueness)
   EXPECT_EQ(span_f_lib_count, 0);
   EXPECT_EQ(span_f_f1_count, 0);
   EXPECT_EQ(span_f_f2_count, 0);
+  EXPECT_EQ(span_g_lib_count, 0);
+  EXPECT_EQ(span_g_f1_count, 0);
+  EXPECT_EQ(span_g_f2_count, 0);
+  EXPECT_EQ(span_h_lib_count, 0);
+  EXPECT_EQ(span_h_f1_count, 0);
+  EXPECT_EQ(span_h_f2_count, 0);
   EXPECT_EQ(unknown_span_count, 0);
 
   reset_counts();
@@ -261,6 +347,16 @@ TEST(SingletonTest, Uniqueness)
   EXPECT_EQ(span_f_lib_count, 1);
   EXPECT_EQ(span_f_f1_count, 2);
   EXPECT_EQ(span_f_f2_count, 1);
+
+#ifndef BAZEL_BUILD
+  EXPECT_EQ(span_g_lib_count, 1);
+  EXPECT_EQ(span_g_f1_count, 2);
+  EXPECT_EQ(span_g_f2_count, 1);
+  EXPECT_EQ(span_h_lib_count, 1);
+  EXPECT_EQ(span_h_f1_count, 2);
+  EXPECT_EQ(span_h_f2_count, 1);
+#endif
+
   EXPECT_EQ(unknown_span_count, 0);
 
   reset_counts();
@@ -286,5 +382,11 @@ TEST(SingletonTest, Uniqueness)
   EXPECT_EQ(span_f_lib_count, 0);
   EXPECT_EQ(span_f_f1_count, 0);
   EXPECT_EQ(span_f_f2_count, 0);
+  EXPECT_EQ(span_g_lib_count, 0);
+  EXPECT_EQ(span_g_f1_count, 0);
+  EXPECT_EQ(span_g_f2_count, 0);
+  EXPECT_EQ(span_h_lib_count, 0);
+  EXPECT_EQ(span_h_f1_count, 0);
+  EXPECT_EQ(span_h_f2_count, 0);
   EXPECT_EQ(unknown_span_count, 0);
 }