推荐|HarmonyOS Next开发学习手册——Node-API接口从异步线程向ArkTS线程投递指定优先级和入队方式的的任务

Node-API中的napi_call_threadsafe_function_with_priority接口的功能是从异步线程向ArkTS线程投递任务，底层队列会根据任务的优先级和入队方式来处理任务。

函数说明

napi_status napi_call_threadsafe_function_with_priority(napi_threadsafe_function func,
                                                        void *data,
                                                        napi_task_priority priority,
                                                        bool isTail);

参数	说明
func	线程安全方法
data	异步线程期望传递给主线程的数据
priority	指定任务的优先级 napi_task_priority
isTail	指定任务的入队方式, true代表任务从队列的尾部入队，false代表任务从队列的头部入队。

场景介绍

异步线程向ArkTS线程投递的任务需要根据任务指定的优先级和入队方式进行处理。

调用异步的ArkTS接口示例

示例代码

模块注册

 // hello.cpp
 #include "napi/native_api.h"
 #include 
 #include 

 struct CallbackData {
     napi_threadsafe_function tsfn;
     napi_async_work work;
 };
 // ArkTS线程的回调实现
 static void CallJs(napi_env env, napi_value jsCb, void *context, void *data) {
     if (env == nullptr) {
         return;
     }
     napi_value resultNumber = nullptr;
     napi_value undefined = nullptr;
     napi_get_undefined(env, &undefined);
     napi_value number1 = nullptr;
     napi_create_int32(env, 12, &number1);
     napi_value number2 = nullptr;
     napi_create_int32(env, 15, &number2);
     napi_value argv[2] = {number1, number2};
     napi_call_function(env, undefined, jsCb, 2, argv, &resultNumber);
     int32_t res = 0;
     napi_get_value_int32(env, resultNumber, &res);
 }

 // 异步线程中调用该接口向ArkTS线程投递指定优先级和入队方式的任务
 static void ExecuteWork(napi_env env, void *data) {
     CallbackData *callbackData = reinterpret_cast(data);
     // 执行任务为napi_priority_idle优先级，入队方式为队列尾部入队
     napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_idle, true);
     napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_low, true);
     napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_high, true);
     napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_immediate, true);
     // 执行任务为napi_priority_high优先级，入队方式为队列头部入队
     napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_high, false);
 }

 static void WorkComplete(napi_env env, napi_status status, void *data) {
     CallbackData *callbackData = reinterpret_cast(data);
     napi_release_threadsafe_function(callbackData->tsfn, napi_tsfn_release);
     napi_delete_async_work(env, callbackData->work);
     callbackData->work = nullptr;
     callbackData->tsfn = nullptr;
 }

 static napi_value CallThreadSafeWithPriority(napi_env env, napi_callback_info info) {
     size_t argc = 1;
     napi_value jsCb = nullptr;
     CallbackData *callbackData = nullptr;
     napi_get_cb_info(env, info, &argc, &jsCb, nullptr, reinterpret_cast(&callbackData));
     napi_value resourceName = nullptr;
     napi_create_string_utf8(env, "Thread-safe Function Demo", NAPI_AUTO_LENGTH, &resourceName);
     napi_create_threadsafe_function(env, jsCb, nullptr, resourceName, 0, 1, callbackData, nullptr, callbackData, CallJs,
                                     &callbackData->tsfn);
     napi_create_async_work(env, nullptr, resourceName, ExecuteWork, WorkComplete, callbackData, &callbackData->work);
     napi_queue_async_work(env, callbackData->work);
     return nullptr;
 }

 // 注册模块接口
 EXTERN_C_START
 static napi_value Init(napi_env env, napi_value exports)
 {
     CallbackData *callbackData = new CallbackData();
     napi_property_descriptor desc[] = {
         { "callThreadSafeWithPriority", nullptr, CallThreadSafeWithPriority, nullptr, nullptr, nullptr, napi_default, callbackData }
     };
     napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
     return exports;
 }
 EXTERN_C_END

 static napi_module nativeModule = {
     .nm_version = 1,
     .nm_flags = 0,
     .nm_filename = nullptr,
     .nm_register_func = Init,
     .nm_modname = "entry",
     .nm_priv = nullptr,
     .reserved = { 0 },
 };

 extern "C" __attribute__((constructor)) void RegisterEntryModule()
 {
     napi_module_register(&nativeModule);
 }

接口声明

// index.d.ts
export const callThreadSafeWithPriority: (cb: (a: number, b: number) => number) => void;

编译配置

CMakeLists.txt文件需要按照如下配置

// CMakeLists.txt
# the minimum version of CMake.
cmake_minimum_required(VERSION 3.4.1)
project(myapplication)

set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})

if(DEFINED PACKAGE_FIND_FILE)
    include(${PACKAGE_FIND_FILE})
endif()

include_directories(${NATIVERENDER_ROOT_PATH}
                    ${NATIVERENDER_ROOT_PATH}/include)
add_library(entry SHARED hello.cpp)
target_link_libraries(entry PUBLIC libace_napi.z.so)

ArkTS代码示例

// index.ets
import testNapi from 'libentry.so'

let callback = (a: number, b: number) : number => {
    console.info('result is ' + (a + b))
    return a + b;
}
testNapi.callThreadSafeWithPriority(callback);

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