ArkTs学习之ArkTS装饰器@Concurrent装饰器（十）

一、概述

在使用TaskPool时，执行的并发函数需要使用该装饰器修饰，否则无法通过相关校验。

说明：从API version 9开始，该装饰器支持在ArkTS卡片中使用。

二、装饰器说明

说明：并发函数中返回Promise的表现需关注，其中并发同步函数会处理返回该Promise并返回结果。

🌰 1. 示例一：

import taskpool from '@ohos.taskpool';
 
@Concurrent
function testPromise(args1: number, args2: number): Promise<number> {
  return new Promise<number>((testFuncA, testFuncB)=>{
    testFuncA(args1 + args2);
  });
}
 
@Concurrent
async function testPromise1(args1: number, args2: number): Promise<number> {
  return new Promise<number>((testFuncA, testFuncB)=>{
    testFuncA(args1 + args2);
  });
}
 
@Concurrent
async function testPromise2(args1: number, args2: number): Promise<number> {
  return await new Promise<number>((testFuncA, testFuncB)=>{
    testFuncA(args1 + args2)
  });
}
 
@Concurrent
function testPromise3() {
  return Promise.resolve(1);
}
 
@Concurrent
async function testPromise4(): Promise<number> {
  return 1;
}
 
@Concurrent
async function testPromise5(): Promise<string> {
  return await new Promise((resolve) => {
    setTimeout(()=>{
      resolve("Promise setTimeout after resolve");
    }, 1000)
  });
}
 
async function testConcurrentFunc() {
  let task1: taskpool.Task = new taskpool.Task(testPromise, 1, 2);
  let task2: taskpool.Task = new taskpool.Task(testPromise1, 1, 2);
  let task3: taskpool.Task = new taskpool.Task(testPromise2, 1, 2);
  let task4: taskpool.Task = new taskpool.Task(testPromise3);
  let task5: taskpool.Task = new taskpool.Task(testPromise4);
  let task6: taskpool.Task = new taskpool.Task(testPromise5);
 
  taskpool.execute(task1).then((d:object)=>{
    console.info("task1 res is: " + d)
  }).catch((e:object)=>{
    console.info("task1 catch e: " + e)
  })
  taskpool.execute(task2).then((d:object)=>{
    console.info("task2 res is: " + d)
  }).catch((e:object)=>{
    console.info("task2 catch e: " + e)
  })
  taskpool.execute(task3).then((d:object)=>{
    console.info("task3 res is: " + d)
  }).catch((e:object)=>{
    console.info("task3 catch e: " + e)
  })
  taskpool.execute(task4).then((d:object)=>{
    console.info("task4 res is: " + d)
  }).catch((e:object)=>{
    console.info("task4 catch e: " + e)
  })
  taskpool.execute(task5).then((d:object)=>{
    console.info("task5 res is: " + d)
  }).catch((e:object)=>{
    console.info("task5 catch e: " + e)
  })
  taskpool.execute(task6).then((d:object)=>{
    console.info("task6 res is: " + d)
  }).catch((e:object)=>{
    console.info("task6 catch e: " + e)
  })
}
 
testConcurrentFunc();

输出结果如下所示：

task1 res is: 3
task2 catch e: Error: Can't return Promise in pending state
task3 res is: 3
task4 res is: 1
task5 res is: 1
task6 res is: Promise setTimeout after resolve

说明：并发异步方法中如果使用Promise，建议搭配await使用捕获Promise中可能发生的异常。推荐使用示例如下。

🌰 2. 示例二：

@Concurrent
async function testPromiseError() {
  await new Promise<number>((resolve, reject) => {
    resolve(1);
  }).then(()=>{
    throw new Error("testPromise Error");
  })
}
 
@Concurrent
async function testPromiseError1() {
  await new Promise<string>((resolve, reject) => {
    reject("testPromiseError1 Error msg");
  })
}
 
@Concurrent
function testPromiseError2() {
  return new Promise<string>((resolve, reject) => {
    reject("testPromiseError2 Error msg");
  })
}
 
async function testConcurrentFunc() {
  let task1: taskpool.Task = new taskpool.Task(testPromiseError);
  let task2: taskpool.Task = new taskpool.Task(testPromiseError1);
  let task3: taskpool.Task = new taskpool.Task(testPromiseError2);
 
  taskpool.execute(task1).then((d:object)=>{
    console.info("task1 res is: " + d)
  }).catch((e:object)=>{
    console.info("task1 catch e: " + e)
  })
  taskpool.execute(task2).then((d:object)=>{
    console.info("task2 res is: " + d)
  }).catch((e:object)=>{
    console.info("task2 catch e: " + e)
  })
  taskpool.execute(task3).then((d:object)=>{
    console.info("task3 res is: " + d)
  }).catch((e:object)=>{
    console.info("task3 catch e: " + e)
  })
}
 
testConcurrentFunc()

输出结果如下所示：

task1 catch e: Error: testPromise Error
task2 catch e: testPromiseError1 Error msg
task3 catch e: testPromiseError2 Error msg