Add cross-platform logging

Author: kraenhansen

packages/react-native-node-api-modules/android/CMakeLists.txt

@@ -17,6 +17,7 @@ target_include_directories(weak-node-api INTERFACE
 
 add_library(node-api-host SHARED
   src/main/cpp/OnLoad.cpp
+  ../cpp/Logger.cpp
   ../cpp/CxxNodeApiHostModule.cpp
   ../cpp/WeakNodeApiInjector.cpp
 )
@@ -27,9 +28,10 @@ target_include_directories(node-api-host PRIVATE
 
 target_link_libraries(node-api-host
   # android
+  log
   ReactAndroid::reactnative
   ReactAndroid::jsi
   hermes-engine::libhermes
   weak-node-api
   # react_codegen_NodeApiHostSpec
-)
+)

packages/react-native-node-api-modules/cpp/AddonLoaders.hpp

@@ -1,20 +1,25 @@
 #pragma once
+#include "Logger.hpp"
+
 #include <assert.h>
 
 #if defined(__APPLE__) || defined(__ANDROID__)
 #include <dlfcn.h>
 #include <stdio.h>
 
+using callstack::nodeapihost::log_debug;
+
 struct PosixLoader {
   using Module = void *;
   using Symbol = void *;
 
   static Module loadLibrary(const char *filePath) {
     assert(NULL != filePath);
+
     Module result = dlopen(filePath, RTLD_NOW | RTLD_LOCAL);
     if (NULL == result) {
-      fprintf(stderr, "NapiHost: Failed to load library '%s': %s", filePath,
-              dlerror());
+      log_debug("NapiHost: Failed to load library '%s': %s", filePath,
+                dlerror());
     }
     return result;
   }

packages/react-native-node-api-modules/cpp/CxxNodeApiHostModule.cpp

@@ -1,4 +1,5 @@
 #include "CxxNodeApiHostModule.hpp"
+#include "Logger.hpp"
 
 using namespace facebook;
 
@@ -58,10 +59,14 @@ bool CxxNodeApiHostModule::loadNodeAddon(NodeAddon &addon,
   abort()
 #endif
 
+  log_debug("[%s] Loading addon by '%s'", libraryName.c_str(),
+            libraryPath.c_str());
+
   typename LoaderPolicy::Symbol initFn = NULL;
   typename LoaderPolicy::Module library =
       LoaderPolicy::loadLibrary(libraryPath.c_str());
   if (NULL != library) {
+    log_debug("[%s] Loaded addon", libraryName.c_str());
     addon.moduleHandle = library;
 
     // Generate a name allowing us to reference the exports object from JSI
@@ -73,12 +78,20 @@ bool CxxNodeApiHostModule::loadNodeAddon(NodeAddon &addon,
 
     initFn = LoaderPolicy::getSymbol(library, "napi_register_module_v1");
     if (NULL != initFn) {
+      log_debug("[%s] Found napi_register_module_v1 (%p)", libraryName.c_str(),
+                initFn);
       addon.init = (napi_addon_register_func)initFn;
+    } else {
+      log_debug("[%s] Failed to find napi_register_module_v1. Expecting the "
+                "addon to call napi_module_register to register itself.",
+                libraryName.c_str());
     }
     // TODO: Read "node_api_module_get_api_version_v1" to support the addon
     // declaring its Node-API version
     // @see
     // https://github.com/callstackincubator/react-native-node-api-modules/issues/4
+  } else {
+    log_debug("[%s] Failed to load library", libraryName.c_str());
   }
   return NULL != initFn;
 }

packages/react-native-node-api-modules/cpp/Logger.cpp

@@ -0,0 +1,35 @@
+#include "Logger.hpp"
+#include <cstdarg>
+#include <cstdio>
+
+#if defined(__ANDROID__)
+#include <android/log.h>
+#define LOG_TAG "NodeApiHost"
+#elif defined(__APPLE__)
+#include <TargetConditionals.h>
+#endif
+
+namespace callstack::nodeapihost {
+void log_debug(const char *format, ...) {
+  // TODO: Disable logging in release builds
+
+  va_list args;
+  va_start(args, format);
+
+#if defined(__ANDROID__)
+  __android_log_vprint(ANDROID_LOG_DEBUG, LOG_TAG, format, args);
+#elif defined(__APPLE__)
+  // iOS or macOS
+  fprintf(stderr, "[NodeApiHost] ");
+  vfprintf(stderr, format, args);
+  fprintf(stderr, "\n");
+#else
+  // Fallback for other platforms
+  fprintf(stderr, "[NodeApiHost] ");
+  vfprintf(stdout, format, args);
+  fprintf(stdout, "\n");
+#endif
+
+  va_end(args);
+}
+} // namespace callstack::nodeapihost

packages/react-native-node-api-modules/cpp/Logger.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <string>
+
+namespace callstack::nodeapihost {
+void log_debug(const char *format, ...);
+}

packages/react-native-node-api-modules/scripts/generate-weak-node-api-injector.ts

@@ -12,12 +12,14 @@ export const CPP_SOURCE_PATH = path.join(__dirname, "../cpp");
 export function generateSource(functions: FunctionDecl[]) {
   return [
     "// This file is generated by react-native-node-api-modules",
+    `#include <Logger.hpp>`,
     `#include <weak_node_api.hpp>`,
     "namespace callstack::nodeapihost {",
     "using node_api::internal::inject_host;",
     "using node_api::internal::NodeApiHost;",
     "void injectIntoWeakNodeApi() {",
-    "  inject_host(node_api::internal::NodeApiHost {",
+    `  log_debug("Injecting WeakNodeApiHost");`,
+    "  inject_host(NodeApiHost {",
     ...functions
       .filter(({ kind }) => kind === "engine")
       .flatMap(({ name }) => {