[3/N] Add update function in backend interface

runtime/backend/backend_options.h

@@ -10,6 +10,8 @@
 #include <executorch/runtime/core/error.h>
 #include <cstddef>
 #include <cstring>
+#include <executorch/runtime/core/error.h>
+#include <executorch/runtime/core/array_ref.h>
 
 namespace executorch {
 namespace runtime {
@@ -120,6 +122,10 @@ class BackendOptions {
     return err;
   }
 
+  executorch::runtime::ArrayRef<BackendOption> view() const {
+    return executorch::runtime::ArrayRef<BackendOption>(options_, size_);
+  }
+
  private:
   BackendOption options_[MaxCapacity]{};
   size_t size_;

runtime/backend/interface.h

@@ -12,6 +12,8 @@
 
 #include <executorch/runtime/backend/backend_execution_context.h>
 #include <executorch/runtime/backend/backend_init_context.h>
+#include <executorch/runtime/backend/backend_update_context.h>
+#include <executorch/runtime/backend/backend_options.h>
 #include <executorch/runtime/core/array_ref.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/evalue.h>
@@ -99,6 +101,20 @@ class BackendInterface {
       DelegateHandle* handle,
       EValue** args) const = 0;
 
+  /**
+   * Responsible update the backend status, if any. The backend options are passed in
+   * by users, and the backend can update its internal status based on the options.
+   *
+   * @param[in] context Runtime context if any. Currently it's not used.
+   * @param[in] args A list of BackendOptions passed in by users.
+   * @retval Error::Ok if successful.
+   */
+   ET_NODISCARD virtual Error update(
+    BackendUpdateContext& context,
+    const executorch::runtime::ArrayRef<BackendOption>& backend_options) const {
+        return Error::Ok;
+      };
+
   /**
    * Responsible for destroying a handle, if it's required for some backend.
    * It may be needed for some backends. For example, resources associated with

runtime/backend/test/backend_interface_update_test.cpp

@@ -0,0 +1,287 @@
+/*
+ * 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/runtime/backend/interface.h>
+ #include <executorch/runtime/platform/runtime.h>
+
+ #include <gtest/gtest.h>
+
+ using namespace ::testing;
+using executorch::runtime::BackendInterface;
+using executorch::runtime::Result;
+using executorch::runtime::DelegateHandle;
+using executorch::runtime::FreeableBuffer;
+using executorch::runtime::BackendInitContext;
+using executorch::runtime::CompileSpec;
+using executorch::runtime::ArrayRef;
+using executorch::runtime::Error;
+using executorch::runtime::BackendExecutionContext;
+using executorch::runtime::EValue;
+using executorch::runtime::BackendUpdateContext;
+using executorch::runtime::BackendOption;
+using executorch::runtime::BackendOptions;
+using executorch::runtime::Backend;
+using executorch::runtime::StrKey;
+using executorch::runtime::IntKey;
+using executorch::runtime::BoolKey;
+using executorch::runtime::get_backend_class;
+using executorch::runtime::OptionType;
+using executorch::runtime::MemoryAllocator;
+
+class MockBackend : public BackendInterface {
+  public:
+      ~MockBackend() override = default;
+
+      bool is_available() const override { return true; }
+
+      Result<DelegateHandle*> init(
+          BackendInitContext& context,
+          FreeableBuffer* processed,
+          ArrayRef<CompileSpec> compile_specs) const override {
+            init_called = true;
+            return nullptr;
+      }
+
+      Error execute(
+          BackendExecutionContext& context,
+          DelegateHandle* handle,
+          EValue** args) const override {
+            execute_count++;
+            return Error::Ok;
+      }
+
+      Error update(
+          BackendUpdateContext& context,
+          const executorch::runtime::ArrayRef<BackendOption>& backend_options) const override {
+          update_count++;
+          int sucess_update = 0;
+          for (const auto& backend_option : backend_options) {
+            if (strcmp(backend_option.key, "Backend") == 0) {
+                if (backend_option.type == OptionType::STRING) {
+                    // Store the value in our member variable
+                    target_backend = backend_option.value.string_value;
+                    sucess_update++;
+                }
+            } else if (strcmp(backend_option.key, "NumberOfThreads") == 0) {
+                if (backend_option.type == OptionType::INT) {
+                  num_threads = backend_option.value.int_value;
+                  sucess_update++;
+                }
+            } else if (strcmp(backend_option.key, "Debug") == 0) {
+              if (backend_option.type == OptionType::BOOL) {
+                debug = backend_option.value.bool_value;
+                sucess_update++;
+              }
+            }
+          }
+          if (sucess_update == backend_options.size()) {
+            return Error::Ok;
+          }
+          return Error::InvalidArgument;
+      }
+
+      // Mutable allows modification in const methods
+      mutable std::optional<std::string> target_backend;
+      mutable int num_threads = 0;
+      mutable bool debug = false;
+
+      // State tracking
+      mutable bool init_called = false;
+      mutable int execute_count = 0;
+      mutable int update_count = 0;
+};
+
+ class BackendInterfaceUpdateTest : public ::testing::Test {
+  protected:
+
+  void SetUp() override {
+     // Since these tests cause ET_LOG to be called, the PAL must be initialized
+     // first.
+     executorch::runtime::runtime_init();
+     mock_backend = std::make_unique<MockBackend>();
+    //  static Error register_success = register_executor_backend();
+    }
+
+  std::unique_ptr<MockBackend> mock_backend;  
+  BackendOptions<5> options;  
+};
+
+TEST_F(BackendInterfaceUpdateTest, HandlesInvalidOption) {
+  BackendUpdateContext context;
+
+  // Test invalid key case
+  BackendOption invalid_option{
+    "InvalidKey",
+    OptionType::STRING,
+    {.string_value = "None"}
+  };
+
+  Error err = mock_backend->update(context, invalid_option);
+  EXPECT_EQ(err, Error::InvalidArgument);
+
+}
+
+ TEST_F(BackendInterfaceUpdateTest, HandlesStringOption) {
+  BackendUpdateContext context;
+  options.set_option(StrKey("Backend"), "GPU");  
+  // // Create a backend option to pass to update
+
+  EXPECT_EQ(mock_backend->target_backend, std::nullopt);
+
+  // Test successful update
+  Error err = mock_backend->update(context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  EXPECT_EQ(mock_backend->target_backend, "GPU");
+}
+
+TEST_F(BackendInterfaceUpdateTest, HandlesIntOption) {
+  // Check the default num_threads value is 0
+  EXPECT_EQ(mock_backend->debug, false);
+  // Create a mock context (needs to be defined or mocked)
+  BackendUpdateContext context;
+
+  int expected_num_threads = 4;
+
+  // Create a backend option to pass to update
+  options.set_option(IntKey("NumberOfThreads"), expected_num_threads);  
+
+  // Test successful update
+  Error err = mock_backend->update(context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+  EXPECT_EQ(mock_backend->num_threads, expected_num_threads);
+}
+
+TEST_F(BackendInterfaceUpdateTest, HandlesBoolOption) {
+  // Check the default num_threads value is 0
+  EXPECT_EQ(mock_backend->debug, false);
+  // Create a mock context (needs to be defined or mocked)
+  BackendUpdateContext context;
+
+  options.set_option(BoolKey("Debug"), true);  
+
+  // Test successful update
+  Error err = mock_backend->update(context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  EXPECT_EQ(mock_backend->debug, true);
+}
+
+TEST_F(BackendInterfaceUpdateTest, HandlesMultipleOptions) {
+  // Check the default num_threads value is 0
+  EXPECT_EQ(mock_backend->debug, false);
+  // Create a mock context (needs to be defined or mocked)
+  BackendUpdateContext context;
+
+  options.set_option(BoolKey("Debug"), true);
+  options.set_option(IntKey("NumberOfThreads"), 4);  
+  options.set_option(StrKey("Backend"), "GPU");  
+
+  // Test successful update
+  Error err = mock_backend->update(context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  EXPECT_EQ(mock_backend->debug, true);
+  EXPECT_EQ(mock_backend->num_threads, 4);
+  EXPECT_EQ(mock_backend->target_backend, "GPU");
+}
+
+TEST_F(BackendInterfaceUpdateTest, UpdateBeforeInit) {
+  BackendUpdateContext update_context;
+  MemoryAllocator memory_allocator{MemoryAllocator(0, nullptr)};
+
+  BackendInitContext init_context(&memory_allocator);
+
+  // Create backend option
+  options.set_option(StrKey("Backend"), "GPU");
+
+  // Update before init
+  Error err = mock_backend->update(update_context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  // Now call init
+  FreeableBuffer* processed = nullptr;  // Not used in mock
+  ArrayRef<CompileSpec> compile_specs;  // Empty
+  auto handle_or_error = mock_backend->init(init_context, processed, compile_specs);
+  EXPECT_EQ(handle_or_error.error(), Error::Ok);
+
+  // Verify state
+  EXPECT_TRUE(mock_backend->init_called);
+  EXPECT_EQ(mock_backend->update_count, 1);
+  EXPECT_EQ(mock_backend->execute_count, 0);
+  ASSERT_TRUE(mock_backend->target_backend.has_value());
+  EXPECT_STREQ(mock_backend->target_backend.value().c_str(), "GPU");
+}
+
+TEST_F(BackendInterfaceUpdateTest, UpdateAfterInitBeforeExecute) {
+  BackendUpdateContext update_context;
+  MemoryAllocator init_memory_allocator{MemoryAllocator(0, nullptr)};
+  BackendInitContext init_context(&init_memory_allocator);
+  BackendExecutionContext execute_context;
+
+  // First call init
+  FreeableBuffer* processed = nullptr;
+  ArrayRef<CompileSpec> compile_specs;
+  auto handle_or_error = mock_backend->init(init_context, processed, compile_specs);
+  EXPECT_TRUE(handle_or_error.ok());
+
+  // Verify init called but execute not called
+  EXPECT_TRUE(mock_backend->init_called);
+  EXPECT_EQ(mock_backend->execute_count, 0);
+
+  // Now update
+  options.set_option(StrKey("Backend"), "CPU");
+  Error err = mock_backend->update(update_context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  // Now execute
+  DelegateHandle* handle = handle_or_error.get();
+  EValue** args = nullptr;  // Not used in mock
+  err = mock_backend->execute(execute_context, handle, args);
+  EXPECT_EQ(err, Error::Ok);
+
+  // Verify state
+  EXPECT_EQ(mock_backend->update_count, 1);
+  EXPECT_EQ(mock_backend->execute_count, 1);
+  ASSERT_TRUE(mock_backend->target_backend.has_value());
+  EXPECT_STREQ(mock_backend->target_backend.value().c_str(), "CPU");
+}
+
+TEST_F(BackendInterfaceUpdateTest, UpdateBetweenExecutes) {
+  BackendUpdateContext update_context;
+  MemoryAllocator init_memory_allocator{MemoryAllocator(0, nullptr)};
+  BackendInitContext init_context(&init_memory_allocator);
+  BackendExecutionContext execute_context;
+
+  // Initialize
+  FreeableBuffer* processed = nullptr;
+  ArrayRef<CompileSpec> compile_specs;
+  auto handle_or_error = mock_backend->init(init_context, processed, compile_specs);
+  EXPECT_TRUE(handle_or_error.ok());
+  DelegateHandle* handle = handle_or_error.get();
+
+  // First execute
+  EValue** args = nullptr;
+  Error err = mock_backend->execute(execute_context, handle, args);
+  EXPECT_EQ(err, Error::Ok);
+
+  // Update between executes
+  options.set_option(StrKey("Backend"), "NPU");
+  err = mock_backend->update(update_context, options.view());
+  EXPECT_EQ(err, Error::Ok);
+
+  // Second execute
+  err = mock_backend->execute(execute_context, handle, args);
+  EXPECT_EQ(err, Error::Ok);
+
+  // Verify state
+  EXPECT_EQ(mock_backend->update_count, 1);
+  EXPECT_EQ(mock_backend->execute_count, 2);
+  ASSERT_TRUE(mock_backend->target_backend.has_value());
+  EXPECT_STREQ(mock_backend->target_backend.value().c_str(), "NPU");
+}

runtime/backend/test/targets.bzl

@@ -14,3 +14,12 @@ def define_common_targets():
             "//executorch/runtime/backend:interface",
         ],
     )
+
+    runtime.cxx_test(
+        name = "backend_interface_update_test",
+        srcs = ["backend_interface_update_test.cpp"],
+        deps = [
+            "//executorch/runtime/core:core",
+            "//executorch/runtime/backend:interface",
+        ],
+    )