AGENTS

This file provides guidance for AI agents when working with code in the patch component.

Overview

This directory contains the patch system for the ArkCompiler ECMAScript runtime. The patch system enables runtime code replacement through three main mechanisms:

• Hot Reload: Live code updates during development without restarting the application
• Cold Patch: Loads patch files at application startup instead of the original files

Architecture

Core Components

• patch_loader.h/cpp: Core patch loading/unloading logic
• quick_fix_manager.h/cpp: Manages quick fix lifecycle
• quick_fix_helper.h/cpp: Helper utilities for quick fixes

Key Data Structures

• PatchMethodIndex: Identifies methods to patch (recordName, className, methodName)
• BaseMethodIndex: Identifies original methods (constpoolNum, constpoolIndex, literalIndex)
• PatchInfo: Contains all patch metadata including method literals and constpools
• ReplacedMethod: Tracks which methods have been replaced

Method Replacement Strategy

1. Methods are identified by PatchMethodIndex in the patch file
2. Original method info is saved using BaseMethodIndex
3. ReplaceMethod() updates:
   • Call fields
   • Literal info
   • Code entry points
   • Native pointers
   • Constant pools

Building

This project uses the GN (Generate Ninja) build system, integrated with the larger OpenHarmony/ArkCompiler build infrastructure.

Build Commands

Full OpenHarmony build (from repository root):

# Host tools (Linux x64)
./build.sh --product-name rk3568 --build-target ark_js_host_linux_tools_packages

# Device targets (libark_jsruntime shared object)
./build.sh --product-name rk3568 --build-target libark_jsruntime

# Add --gn-args is_debug=true for debug builds

Testing

Test Structure

Test cases are located in /arkcompiler/ets_runtime/test/quickfix/.

Running Tests

From the ark_standalone_build directory:

cd ark_standalone_build
python ark.py x64.release ark_quickfix_test  # Quick fix tests (release build)