Add Android standalone log target (#6590)

Summary:

Add a standalone Android log target to enable ExecuTorch logging to logcat when not using JNI bindings.

Reviewed By: kirklandsign

Differential Revision: D65268257

Author: GregoryComer

extension/android/BUCK

@@ -1,4 +1,5 @@
 load("@fbsource//tools/build_defs/android:fb_android_library.bzl", "fb_android_library")
+load("@fbsource//tools/build_defs:fb_xplat_cxx_library.bzl", "fb_xplat_cxx_library")
 
 oncall("executorch")
 
@@ -39,3 +40,17 @@ fb_android_library(
         "//fbandroid/libraries/soloader/java/com/facebook/soloader/nativeloader:nativeloader",
     ],
 )
+
+fb_xplat_cxx_library(
+    name = "log_provider",
+    srcs = ["jni/log.cpp"],
+    compiler_flags = [
+        "-frtti",
+        "-fexceptions",
+        "-Wno-unused-variable",
+    ],
+    deps = [
+        "//xplat/executorch/runtime/platform:platform",
+    ],
+    visibility = ["PUBLIC"],
+)

extension/android/CMakeLists.txt

@@ -64,7 +64,7 @@ set(executorch_DIR ${CMAKE_CURRENT_BINARY_DIR}/../../lib/cmake/ExecuTorch)
 find_package(executorch CONFIG REQUIRED)
 target_link_options_shared_lib(executorch)
 
-add_library(executorch_jni SHARED jni/jni_layer.cpp)
+add_library(executorch_jni SHARED jni/jni_layer.cpp jni/log.cpp)
 
 set(link_libraries)
 list(
@@ -146,7 +146,7 @@ if(EXECUTORCH_JNI_CUSTOM_LIBRARY)
 endif()
 
 if(EXECUTORCH_BUILD_LLAMA_JNI)
-  target_sources(executorch_jni PRIVATE jni/jni_layer_llama.cpp)
+  target_sources(executorch_jni PRIVATE jni/jni_layer_llama.cpp log.cpp)
   list(APPEND link_libraries llama_runner llava_runner)
   target_compile_definitions(executorch_jni PUBLIC EXECUTORCH_BUILD_LLAMA_JNI=1)
   add_subdirectory(

extension/android/jni/BUCK

@@ -25,7 +25,7 @@ executorch_generated_lib(
 
 fb_android_cxx_library(
     name = "executorch_jni",
-    srcs = ["jni_layer.cpp"],
+    srcs = ["jni_layer.cpp", "log.cpp"],
     headers = ["jni_layer_constants.h"],
     allow_jni_merging = False,
     compiler_flags = [
@@ -49,7 +49,7 @@ fb_android_cxx_library(
 
 fb_android_cxx_library(
     name = "executorch_jni_full",
-    srcs = ["jni_layer.cpp"],
+    srcs = ["jni_layer.cpp", "log.cpp"],
     headers = ["jni_layer_constants.h"],
     allow_jni_merging = False,
     compiler_flags = [

extension/android/jni/jni_layer.cpp

@@ -36,76 +36,6 @@
 using namespace executorch::extension;
 using namespace torch::executor;
 
-#ifdef __ANDROID__
-#include <android/log.h>
-#include <mutex>
-#include <sstream>
-
-// Number of entries to store in the in-memory log buffer.
-const size_t log_buffer_length = 16;
-
-struct log_entry {
-  et_timestamp_t timestamp;
-  et_pal_log_level_t level;
-  std::string filename;
-  std::string function;
-  size_t line;
-  std::string message;
-
-  log_entry(
-      et_timestamp_t timestamp,
-      et_pal_log_level_t level,
-      const char* filename,
-      const char* function,
-      size_t line,
-      const char* message,
-      size_t length)
-      : timestamp(timestamp),
-        level(level),
-        filename(filename),
-        function(function),
-        line(line),
-        message(message, length) {}
-};
-
-namespace {
-std::vector<log_entry> log_buffer_;
-std::mutex log_buffer_mutex_;
-} // namespace
-
-// For Android, write to logcat
-void et_pal_emit_log_message(
-    et_timestamp_t timestamp,
-    et_pal_log_level_t level,
-    const char* filename,
-    const char* function,
-    size_t line,
-    const char* message,
-    size_t length) {
-  std::lock_guard<std::mutex> guard(log_buffer_mutex_);
-
-  while (log_buffer_.size() >= log_buffer_length) {
-    log_buffer_.erase(log_buffer_.begin());
-  }
-
-  log_buffer_.emplace_back(
-      timestamp, level, filename, function, line, message, length);
-
-  int android_log_level = ANDROID_LOG_UNKNOWN;
-  if (level == 'D') {
-    android_log_level = ANDROID_LOG_DEBUG;
-  } else if (level == 'I') {
-    android_log_level = ANDROID_LOG_INFO;
-  } else if (level == 'E') {
-    android_log_level = ANDROID_LOG_ERROR;
-  } else if (level == 'F') {
-    android_log_level = ANDROID_LOG_FATAL;
-  }
-
-  __android_log_print(android_log_level, "ExecuTorch", "%s", message);
-}
-#endif
-
 namespace executorch::extension {
 class TensorHybrid : public facebook::jni::HybridClass<TensorHybrid> {
  public:
@@ -437,24 +367,26 @@ class ExecuTorchJni : public facebook::jni::HybridClass<ExecuTorchJni> {
   facebook::jni::local_ref<facebook::jni::JArrayClass<jstring>>
   readLogBuffer() {
 #ifdef __ANDROID__
-    std::lock_guard<std::mutex> guard(log_buffer_mutex_);
 
     const auto size = log_buffer_.size();
     facebook::jni::local_ref<facebook::jni::JArrayClass<jstring>> ret =
         facebook::jni::JArrayClass<jstring>::newArray(size);
 
-    for (auto i = 0u; i < size; i++) {
-      const auto& entry = log_buffer_[i];
-      // Format the log entry as "[TIMESTAMP FUNCTION FILE:LINE] LEVEL MESSAGE".
-      std::stringstream ss;
-      ss << "[" << entry.timestamp << " " << entry.function << " "
-         << entry.filename << ":" << entry.line << "] "
-         << static_cast<char>(entry.level) << " " << entry.message;
-
-      facebook::jni::local_ref<facebook::jni::JString> jstr_message =
-          facebook::jni::make_jstring(ss.str().c_str());
-      (*ret)[i] = jstr_message;
-    }
+    access_log_buffer([&](std::vector<log_entry>& buffer) {
+      for (auto i = 0u; i < size; i++) {
+        const auto& entry = buffer[i];
+        // Format the log entry as "[TIMESTAMP FUNCTION FILE:LINE] LEVEL
+        // MESSAGE".
+        std::stringstream ss;
+        ss << "[" << entry.timestamp << " " << entry.function << " "
+           << entry.filename << ":" << entry.line << "] "
+           << static_cast<char>(entry.level) << " " << entry.message;
+
+        facebook::jni::local_ref<facebook::jni::JString> jstr_message =
+            facebook::jni::make_jstring(ss.str().c_str());
+        (*ret)[i] = jstr_message;
+      }
+    });
 
     return ret;
 #else
@@ -468,10 +400,7 @@ class ExecuTorchJni : public facebook::jni::HybridClass<ExecuTorchJni> {
         makeNativeMethod("forward", ExecuTorchJni::forward),
         makeNativeMethod("execute", ExecuTorchJni::execute),
         makeNativeMethod("loadMethod", ExecuTorchJni::load_method),
-
-#ifdef __ANDROID__
         makeNativeMethod("readLogBuffer", ExecuTorchJni::readLogBuffer),
-#endif
     });
   }
 };

extension/android/jni/log.cpp

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <executorch/extension/android/jni/log.h>
+
+#include <android/log.h>
+#include <functional>
+#include <mutex>
+#include <sstream>
+
+// Number of entries to store in the in-memory log buffer.
+const size_t log_buffer_length = 16;
+
+namespace {
+std::vector<log_entry> log_buffer_;
+std::mutex log_buffer_mutex_;
+} // namespace
+
+// For Android, write to logcat
+void et_pal_emit_log_message(
+    et_timestamp_t timestamp,
+    et_pal_log_level_t level,
+    const char* filename,
+    const char* function,
+    size_t line,
+    const char* message,
+    size_t length) {
+  std::lock_guard<std::mutex> guard(log_buffer_mutex_);
+
+  while (log_buffer_.size() >= log_buffer_length) {
+    log_buffer_.erase(log_buffer_.begin());
+  }
+
+  log_buffer_.emplace_back(
+      timestamp, level, filename, function, line, message, length);
+
+  int android_log_level = ANDROID_LOG_UNKNOWN;
+  if (level == 'D') {
+    android_log_level = ANDROID_LOG_DEBUG;
+  } else if (level == 'I') {
+    android_log_level = ANDROID_LOG_INFO;
+  } else if (level == 'E') {
+    android_log_level = ANDROID_LOG_ERROR;
+  } else if (level == 'F') {
+    android_log_level = ANDROID_LOG_FATAL;
+  }
+
+  __android_log_print(android_log_level, "ExecuTorch", "%s", message);
+}
+
+namespace executorch::extension {
+
+void access_log_buffer(std::function<void(std::vector<log_entry>&)> accessor) {
+  std::lock_guard<std::mutex> guard(log_buffer_mutex_);
+  accessor(log_buffer_);
+}
+
+} // namespace executorch::extension

extension/android/jni/log.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <functional>
+#include <vector>
+
+#include <executorch/runtime/platform/log.h>
+#include <executorch/runtime/platform/platform.h>
+#include <executorch/runtime/platform/runtime.h>
+
+namespace executorch::extension {
+struct log_entry {
+  et_timestamp_t timestamp;
+  et_pal_log_level_t level;
+  std::string filename;
+  std::string function;
+  size_t line;
+  std::string message;
+
+  log_entry(
+      et_timestamp_t timestamp,
+      et_pal_log_level_t level,
+      const char* filename,
+      const char* function,
+      size_t line,
+      const char* message,
+      size_t length)
+      : timestamp(timestamp),
+        level(level),
+        filename(filename),
+        function(function),
+        line(line),
+        message(message, length) {}
+};
+
+void access_log_buffer(std::function<void(std::vector<log_entry>&)> accessor);
+} // namespace executorch::extension