1# 使用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
2Node-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。
3
4## 函数说明
5
6```cpp
7napi_status napi_call_threadsafe_function_with_priority(napi_threadsafe_function func,
8                                                        void *data,
9                                                        napi_task_priority priority,
10                                                        bool isTail);
11```
12
13| 参数            | 说明          |
14| :------------- | :----------------------------- |
15| func           | 线程安全方法                   |
16| data           | 异步线程期望传递给主线程的数据  |
17| priority       | 指定任务的优先级[napi_task_priority](napi-data-types-interfaces.md#线程安全任务优先级) |
18| 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。 |
19
20## 场景介绍
21异步线程向ArkTS主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。
22
23## 调用异步的ArkTS接口示例
24
25### 示例代码
26
27- 模块注册
28
29   ```c++
30    // napi_init.cpp
31    #include "napi/native_api.h"
32    #include <string.h>
33    #include <stdlib.h>
34
35    struct CallbackData {
36        napi_threadsafe_function tsfn;
37        napi_async_work work;
38    };
39    // ArkTS线程的回调实现
40    static void CallJs(napi_env env, napi_value jsCb, void *context, void *data) {
41        if (env == nullptr) {
42            return;
43        }
44        napi_value resultNumber = nullptr;
45        napi_value undefined = nullptr;
46        napi_get_undefined(env, &undefined);
47        napi_value number1 = nullptr;
48        napi_create_int32(env, 12, &number1);
49        napi_value number2 = nullptr;
50        napi_create_int32(env, 15, &number2);
51        napi_value argv[2] = {number1, number2};
52        napi_call_function(env, undefined, jsCb, 2, argv, &resultNumber);
53        int32_t res = 0;
54        napi_get_value_int32(env, resultNumber, &res);
55    }
56
57    // 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
58    static void ExecuteWork(napi_env env, void *data) {
59        CallbackData *callbackData = reinterpret_cast<CallbackData *>(data);
60        // 执行任务为napi_priority_idle优先级,入队方式为队列尾部入队
61        napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_idle, true);
62        napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_low, true);
63        napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_high, true);
64        napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_immediate, true);
65        // 执行任务为napi_priority_high优先级,入队方式为队列头部入队
66        napi_call_threadsafe_function_with_priority(callbackData->tsfn, nullptr, napi_priority_high, false);
67    }
68
69    static void WorkComplete(napi_env env, napi_status status, void *data) {
70        CallbackData *callbackData = reinterpret_cast<CallbackData *>(data);
71        napi_release_threadsafe_function(callbackData->tsfn, napi_tsfn_release);
72        napi_delete_async_work(env, callbackData->work);
73        callbackData->work = nullptr;
74        callbackData->tsfn = nullptr;
75    }
76
77    static napi_value CallThreadSafeWithPriority(napi_env env, napi_callback_info info) {
78        size_t argc = 1;
79        napi_value jsCb = nullptr;
80        CallbackData *callbackData = nullptr;
81        napi_get_cb_info(env, info, &argc, &jsCb, nullptr, reinterpret_cast<void **>(&callbackData));
82        napi_value resourceName = nullptr;
83        napi_create_string_utf8(env, "Thread-safe Function Demo", NAPI_AUTO_LENGTH, &resourceName);
84        napi_create_threadsafe_function(env, jsCb, nullptr, resourceName, 0, 1, callbackData, nullptr, callbackData, CallJs,
85                                        &callbackData->tsfn);
86        napi_create_async_work(env, nullptr, resourceName, ExecuteWork, WorkComplete, callbackData, &callbackData->work);
87        napi_queue_async_work(env, callbackData->work);
88        return nullptr;
89    }
90
91    // 注册模块接口
92    EXTERN_C_START
93    static napi_value Init(napi_env env, napi_value exports)
94    {
95        CallbackData *callbackData = new CallbackData();
96        napi_property_descriptor desc[] = {
97            { "callThreadSafeWithPriority", nullptr, CallThreadSafeWithPriority, nullptr, nullptr, nullptr, napi_default, callbackData }
98        };
99        napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
100        return exports;
101    }
102    EXTERN_C_END
103
104    static napi_module nativeModule = {
105        .nm_version = 1,
106        .nm_flags = 0,
107        .nm_filename = nullptr,
108        .nm_register_func = Init,
109        .nm_modname = "entry",
110        .nm_priv = nullptr,
111        .reserved = { 0 },
112    };
113
114    extern "C" __attribute__((constructor)) void RegisterEntryModule()
115    {
116        napi_module_register(&nativeModule);
117    }
118   ```
119
120- 接口声明
121
122    ```ts
123    // index.d.ts
124    export const callThreadSafeWithPriority: (cb: (a: number, b: number) => number) => void;
125    ```
126
127- 编译配置
128
129  CMakeLists.txt文件需要按照如下配置
130
131    ```
132    // CMakeLists.txt
133    # the minimum version of CMake.
134    cmake_minimum_required(VERSION 3.4.1)
135    project(myapplication)
136
137    set(NATIVERENDER_ROOT_PATH ${CMAKE_CURRENT_SOURCE_DIR})
138
139    if(DEFINED PACKAGE_FIND_FILE)
140        include(${PACKAGE_FIND_FILE})
141    endif()
142
143    include_directories(${NATIVERENDER_ROOT_PATH}
144                        ${NATIVERENDER_ROOT_PATH}/include)
145    add_library(entry SHARED hello.cpp)
146    target_link_libraries(entry PUBLIC libace_napi.z.so)
147    ```
148
149- ArkTS代码示例
150
151    ```ts
152    // index.ets
153    import testNapi from 'libentry.so'
154
155    let callback = (a: number, b: number) : number => {
156        console.info('result is ' + (a + b))
157        return a + b;
158    }
159    testNapi.callThreadSafeWithPriority(callback);
160    ```