JS Worker 在继续之前等待消息

Question

我的工人向主脚本发送消息，然后主脚本响应。我想在继续工作之前等待响应，因为响应包含我需要的信息 (memoryAvailable)。

Main.js

export function convert(){
let managingWorker = new Worker("managingWorker.js");
let fileNode = document.querySelector('.fileInput');
managingWorker.postMessage({fileList:fileNode.files, msgType:"processData", options:{delimiter: 
document.querySelector('#specifyDelimiter').value.trim() || ","}});

managingWorker.onmessage = function(e){
    switch(e.data.msgType){
        case "memoryInfoRequested":
            let memAvail = performance.memory.jsHeapSizeLimit - performance.memory.totalJSHeapSize;
            managingWorker.postMessage({msgType:"memoryInfoReceived", memoryAvailable: memAvail});
            break;
     //Other cases for updating the UI
   }

managingWorker.js
 
 let memoryAvailable = 0;

 onmessage = function(e){
    switch(e.data.msgType){
    case "processData":
            workerStuff(e)
    break;
    case "memoryInfoReceived":
        memoryAvailable = e.data.memoryAvailable
    break;
    }
 }

function workerStuff(f){
    //do stuff
    postMessage({msgType:"memoryInfoRequested"})
    //do more stuff if there is enough memory available, else wait

}

我已经尝试过：在 worker 中放置一个 while 循环 while(memoryAvailable < 5){//什么都不做} 但随后工作人员陷入 while 循环，永远没有机会收到消息。

我目前在想我可以使用 async await 和 setTimeout 暂停 x 毫秒，然后在 promise 被解决时，消息应该被传递，但即使我让它工作，它也不是最优解。 *我现在脑子有点炸了，所以也许晚饭后我会尝试这样的事情。

Answer 1

所以，我还没有测试过这个，但我认为我会这样处理它：

managingWorker.js
 

 let waitForMemoryResolve = () => {};

 onmessage = function(e){
    switch(e.data.msgType){
    case "processData":
            workerStuff(e)
    break;
    case "memoryInfoReceived":
        memoryAvailable = e.data.memoryAvailable;
        waitForMemoryResolve(memoryAvailable);
    break;
    }
 }

function workerStuff(f){
    //do stuff
    let memoryAvailable = await waitForMemory();
    while (memoryAvailable < 2000) { // or whatever memory you want
         await new Promise(r => setTimeout(r, 500)); // wait a half second and check again
         memoryAvailable = await waitForMemory();
    }
    
   // once here, we have > 2000 memory, so begin work

}

async function waitForMemory() {
    return new Promise((resolve, reject) => {
      waitForMemoryResolve = resolve;
      postMessage({msgType:"memoryInfoRequested"})
    })   
}

您可以从其他地方的 promise 内部传递 'resolve' 函数，并允许代码的其他部分解析您的 promise。我会这样使用它。

同样，还没有测试过，但我认为这个想法是合理的

JS Worker 在继续之前等待消息

JS Worker await message before continuing

javascript

worker