opentelemetry-cpp/api/include/opentelemetry/plugin/hook.h

52 lines
2.1 KiB
C++

// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "opentelemetry/nostd/unique_ptr.h"
#include "opentelemetry/version.h"
#ifdef _WIN32
/**
* Cross-platform helper macro to declare the symbol used to load an OpenTelemetry implementation
* as a plugin.
*
* Note: The symbols use weak linkage so as to support using an OpenTelemetry both as a regular
* library and a dynamically loaded plugin. The weak linkage allows for multiple implementations to
* be linked in without getting multiple definition errors.
*/
# define OPENTELEMETRY_DEFINE_PLUGIN_HOOK(X) \
extern "C" { \
extern __declspec(dllexport) opentelemetry::plugin::OpenTelemetryHook const \
OpenTelemetryMakeFactoryImpl; \
\
__declspec(selectany) opentelemetry::plugin::OpenTelemetryHook const \
OpenTelemetryMakeFactoryImpl = X; \
} // extern "C"
#else
# define OPENTELEMETRY_DEFINE_PLUGIN_HOOK(X) \
extern "C" { \
__attribute(( \
weak)) extern opentelemetry::plugin::OpenTelemetryHook const OpenTelemetryMakeFactoryImpl; \
\
opentelemetry::plugin::OpenTelemetryHook const OpenTelemetryMakeFactoryImpl = X; \
} // extern "C"
#endif
OPENTELEMETRY_BEGIN_NAMESPACE
namespace plugin
{
struct LoaderInfo;
class FactoryImpl;
using OpenTelemetryHook =
nostd::unique_ptr<Factory::FactoryImpl> (*)(const LoaderInfo &loader_info,
nostd::unique_ptr<char[]> &error_message);
} // namespace plugin
OPENTELEMETRY_END_NAMESPACE