等待所有请求继续 [英] Wait for all requests to continue

问题描述

请，此代码可以异步完成吗?我遇到了问题，因为所有请求都必须在代码可以继续之前终止，我看到了如何等待一个孤立的请求，但是后来我无法使用循环，如果有人可以的话，我已经尝试解决了一段时间.帮我，那太好了.

Please, can this code be done async? I have problems because all requests must be terminated before the code can continue, I saw something about how wait an isolated request, but then i couldn't use the loop, I've been trying to solve this for a while, if anyone can help me it would e great.

StartCoroutine(GetTexture());    

IEnumerator GetTexture() {

    for (int i = 0; i < 10; i++)
    {
        string url = string.Format("https://galinha.webhost.com/img/{0}.jpg", words[i]);
        UnityWebRequest www = UnityWebRequestTexture.GetTexture(url);
        yield return www.SendWebRequest();

        if(www.isNetworkError || www.isHttpError) {
            selectionSprites.Add(sprites[i]);
        }
        else {
            Texture2D myTexture = ((DownloadHandlerTexture)www.downloadHandler).texture;
            Sprite spriteFromWeb = Sprite.Create(myTexture, new Rect(0, 0, myTexture.width, myTexture.height), new Vector2(0, 0));
            selectionSprites.Add(spriteFromWeb);  
        }

    }//for

推荐答案

此代码可以异步完成吗?

can this code be done async?

请注意， async 是一个关键字，这里有点误导.当然，您可以执行Web请求等操作，但由于大多数Unity API不能在线程上使用，因此代码将完全不同.

note that async is a keyword and a bit misleading here. Ofcourse you can do web requests etc async but the code would be completely different since most of the Unity API can't be used on threads...

协程从不async，但仍在主线程中运行，就像它们是临时的Update方法.实际上，MoveNext对协程的调用是在Update之后立即进行的.

Coroutines are never async but still run in the main thread like if they were temporary Update methods. In fact the MoveNext call for Coroutines is done right after the Update.

所以我想您的意思是

可以并行等待这些请求吗?

can these requests be awaited parallel?

最理想的解决方案是，我可以想象您无需太多更改代码结构的地方就是存储所有 UnityWebRequestAsyncOperation s( SendWebRequest 排列成一个数组，然后yield直到所有它们都是 isDone 例如

Esiest solution I can imagine where you wouldn't have to change your code structure too much would be to store all UnityWebRequestAsyncOperations (what is returned by SendWebRequest in an array and yield until all of them are isDone like e.g.

using System.Linq;

...

IEnumerator GetTexture() 
{
    var requests = new UnityWebRequestAsyncOperation[10];

    // Start all requests
    for (var i = 0; i < 10; i++)
    {
        var url = string.Format("https://galinha.webhost.com/img/{0}.jpg", words[i]);
        var www = UnityWebRequestTexture.GetTexture(url);

        // starts the request but doesn't wait for it for now
        requests[i] = www.SendWebRequest();
    }

    // Now wait for all requests parallel
    yield return new WaitUntil(() => AllRequestsDone(requests));

    // Now evaluate all results
    HandleAllRequestsWhenFinished(requests);
}

private void HandleAllRequestsWhenFinished(UnityWebRequestAsyncOperation[] requests)
{
    for(var i = 0; i < 10; i++)
    {
        var www = requests[i].webRequest;
        if(www.isNetworkError || www.isHttpError) 
        {
            selectionSprites.Add(sprites[i]);
        }
        else 
        {
            Texture2D myTexture = ((DownloadHandlerTexture)www.downloadHandler).texture;
            Sprite spriteFromWeb = Sprite.Create(myTexture, new Rect(0, 0, myTexture.width, myTexture.height), new Vector2(0, 0));
            selectionSprites.Add(spriteFromWeb);  
        }
    }
}

private bool AllRequestsDone(UnityWebRequestAsyncOperation[] requests)
{
    // A little Linq magic
    // returns true if All requests are done
    return requests.All(r => r.isDone);

    // Ofcourse you could do the same using a loop
    //foreach(var r in requests)
    //{
    //    if(!r.isDone) return false;
    //}
    //return true;
} 

出于完整性考虑: WaitUntil 和

For completeness: WaitUntil and Linq All

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