Add a android log implementation

runtime/platform/default/android.cpp

@@ -0,0 +1,190 @@
+/*
+ * 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.
+ */
+
+/**
+ * @file
+ * Default PAL implementations for Android system.
+ */
+
+// This cpp file will provide weak implementations of the symbols declared in
+// Platform.h. Client users can strongly define any or all of the functions to
+// override them.
+#define ET_INTERNAL_PLATFORM_WEAKNESS ET_WEAK
+#include <executorch/runtime/platform/compiler.h>
+#include <executorch/runtime/platform/platform.h>
+
+#include <chrono>
+#include <cstdio>
+#include <cstdlib>
+
+#include <android/log.h>
+
+/**
+ * On debug builds, ensure that `et_pal_init` has been called before
+ * other PAL functions which depend on initialization.
+ */
+#ifdef NDEBUG
+
+/**
+ * Assert that the PAL has been initialized.
+ */
+#define _ASSERT_PAL_INITIALIZED() ((void)0)
+
+#else // NDEBUG
+
+/**
+ * Assert that the PAL has been initialized.
+ */
+#define _ASSERT_PAL_INITIALIZED()                                   \
+  do {                                                              \
+    if (!initialized) {                                             \
+      __android_log_print(                                          \
+          ANDROID_LOG_FATAL,                                        \
+          "ExecuTorch",                                             \
+          "%s",                                                     \
+          "ExecuTorch PAL must be initialized before call to %s()", \
+          ET_FUNCTION);                                             \
+    }                                                               \
+  } while (0)
+
+#endif // NDEBUG
+
+/// Start time of the system (used to zero the system timestamp).
+static std::chrono::time_point<std::chrono::steady_clock> systemStartTime;
+
+/// Flag set to true if the PAL has been successfully initialized.
+static bool initialized = false;
+
+/**
+ * Initialize the platform abstraction layer.
+ *
+ * This function should be called before any other function provided by the PAL
+ * to initialize any global state. Typically overridden by PAL implementer.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_init
+#endif // _MSC_VER
+void et_pal_init(void) {
+  if (initialized) {
+    return;
+  }
+
+  systemStartTime = std::chrono::steady_clock::now();
+  initialized = true;
+}
+
+/**
+ * Immediately abort execution, setting the device into an error state, if
+ * available.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_abort
+#endif // _MSC_VER
+ET_NORETURN void et_pal_abort(void) {
+  std::abort();
+}
+
+/**
+ * Return a monotonically non-decreasing timestamp in system ticks.
+ *
+ * @retval Timestamp value in system ticks.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_current_ticks
+#endif // _MSC_VER
+et_timestamp_t et_pal_current_ticks(void) {
+  _ASSERT_PAL_INITIALIZED();
+  auto systemCurrentTime = std::chrono::steady_clock::now();
+  return std::chrono::duration_cast<std::chrono::nanoseconds>(
+             systemCurrentTime - systemStartTime)
+      .count();
+}
+
+/**
+ * Return the conversion rate from system ticks to nanoseconds, as a fraction.
+ * To convert an interval from system ticks to nanoseconds, multiply the tick
+ * count by the numerator and then divide by the denominator:
+ *   nanoseconds = ticks * numerator / denominator
+ *
+ * @retval The ratio of nanoseconds to system ticks.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_ticks_to_ns_multiplier
+#endif // _MSC_VER
+et_tick_ratio_t et_pal_ticks_to_ns_multiplier(void) {
+  // The system tick interval is 1 nanosecond, so the conversion factor is 1.
+  return {1, 1};
+}
+
+/**
+ * Emit a log message to adb logcat.
+ *
+ * @param[in] timestamp Timestamp of the log event in system ticks since boot.
+ * @param[in] level Severity level of the message. Must be a printable 7-bit
+ *     ASCII uppercase letter.
+ * @param[in] filename Name of the file that created the log event.
+ * @param[in] function Name of the function that created the log event.
+ * @param[in] line Line in the source file where the log event was created.
+ * @param[in] message Message string to log.
+ * @param[in] length Message string length.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_emit_log_message
+#endif // _MSC_VER
+void et_pal_emit_log_message(
+    ET_UNUSED et_timestamp_t timestamp,
+    et_pal_log_level_t level,
+    ET_UNUSED const char* filename,
+    ET_UNUSED const char* function,
+    ET_UNUSED size_t line,
+    const char* message,
+    ET_UNUSED size_t length) {
+  _ASSERT_PAL_INITIALIZED();
+
+  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);
+}
+
+/**
+ * NOTE: Core runtime code must not call this directly. It may only be called by
+ * a MemoryAllocator wrapper.
+ *
+ * Allocates size bytes of memory via malloc.
+ *
+ * @param[in] size Number of bytes to allocate.
+ * @returns the allocated memory, or nullptr on failure. Must be freed using
+ *     et_pal_free().
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_allocate
+#endif // _MSC_VER
+void* et_pal_allocate(size_t size) {
+  return malloc(size);
+}
+
+/**
+ * Frees memory allocated by et_pal_allocate().
+ *
+ * @param[in] ptr Pointer to memory to free. May be nullptr.
+ */
+#ifdef _MSC_VER
+#pragma weak et_pal_free
+#endif // _MSC_VER
+void et_pal_free(void* ptr) {
+  free(ptr);
+}

runtime/platform/targets.bzl

@@ -41,13 +41,16 @@ def define_common_targets():
     # client defined implementations will overide them.
     runtime.cxx_library(
         name = "platform_private",
-        srcs = _select_pal({
-            "minimal": ["default/minimal.cpp"],
-            "posix": ["default/posix.cpp"],
-        }),
+        srcs = select({
+            "ovr_config//os:android": ["default/android.cpp"],
+            "DEFAULT": _select_pal({
+                "minimal": ["default/minimal.cpp"],
+                "posix": ["default/posix.cpp"],
+        })}),
         deps = [
             ":pal_interface",
         ],
+        external_deps = ["log"],
         visibility = [
             "//executorch/core/...",
         ],

scripts/build_android_library.sh

@@ -39,6 +39,7 @@ build_android_native_library() {
     -DANDROID_ABI="${ANDROID_ABI}" \
     -DANDROID_PLATFORM=android-26 \
     -DBUILD_TESTING=OFF \
+    -DEXECUTORCH_PAL_DEFAULT=android \
     -DEXECUTORCH_ENABLE_LOGGING=ON \
     -DEXECUTORCH_LOG_LEVEL=Info \
     -DEXECUTORCH_BUILD_XNNPACK=ON \

shim_et/xplat/executorch/build/env_interface.bzl

@@ -43,6 +43,7 @@ _EXTERNAL_DEPS = {
     "gtest_aten": "//third-party:gtest_aten",
     "libtorch": "//third-party:libtorch",
     "libtorch_python": "//third-party:libtorch_python",
+    "log": [], # Intentionally not supporting OSS buck build log
     # Huggingface Tokenizer
     "nlohmann_json": [], # Intentionally not supporting OSS buck build HF tokenizer.
     "prettytable": "//third-party:prettytable",

tools/cmake/preset/default.cmake

@@ -31,7 +31,7 @@ define_overridable_option(
 )
 define_overridable_option(
   EXECUTORCH_PAL_DEFAULT
-  "Which PAL default implementation to use. Choices: posix, minimal"
+  "Which PAL default implementation to use. Choices: posix, minimal, android"
   STRING "posix"
 )
 define_overridable_option(
@@ -276,7 +276,7 @@ define_overridable_option(
 # At this point all the options should be configured with their final value.
 
 if(NOT EXISTS ${EXECUTORCH_PAL_DEFAULT_FILE_PATH})
-  message(FATAL_ERROR "PAL default implementation (EXECUTORCH_PAL_DEFAULT=${EXECUTORCH_PAL_DEFAULT}) file not found: ${EXECUTORCH_PAL_DEFAULT_FILE_PATH}. Choices: posix, minimal")
+  message(FATAL_ERROR "PAL default implementation (EXECUTORCH_PAL_DEFAULT=${EXECUTORCH_PAL_DEFAULT}) file not found: ${EXECUTORCH_PAL_DEFAULT_FILE_PATH}. Choices: posix, minimal, android")
 endif()