c# - 调用 API 20 次来生成列表，最佳实践？

Question

情况是，我调用一次 API 来获取租户列表，然后对于每个租户，我必须再次调用以获取租户的使用情况列表。遗憾的是，无法通过一次调用获取所有租户的使用情况。

现在我希望尝试通过使这些调用并发来节省时间。然后在最后一个到达后将它们全部放在一起。到目前为止，我的尝试如下:

public async Task<List<Usage>> GetUsagesAsync2(Task<List<Tenant>> tenants)
{
    List<Usage> usages = new List<Usage>();

    foreach (var tenant in await tenants)
    {
        //Generate request
        RestRequest request = new RestRequest("tenants/{tenantID}/usages", Method.Get);
        request.AddParameter("tenantID", tenant.id, ParameterType.UrlSegment);
        request.AddHeader("Authorization", $"Bearer {Token.access_token}");

        //Get response
        RestResponse response = await _client.ExecuteAsync(request)
            .ConfigureAwait(false);

        //Validate response
        if (response.StatusCode != HttpStatusCode.OK)
            throw new Exception("Failed at Getting usages for a tenant: ");

        //Add to list
        var t_usage = JsonConvert.DeserializeObject<Wrapper<Usage>>(response.Content);
        usages.AddRange(t_usage.items);
    }
    return usages;
}

代码运行并执行预期的操作，但我不确定它实际上是异步运行的。运行大约需要 7-8 秒，我发现在网页上等待的时间有点长。

Answer 1

这是并行实现:

.NET 6

public async Task<ConcurrentBag<Usage>> GetUsagesAsync2(Task<List<Tenant>> tenants)
{
    ConcurrentBag<Usage> usages = new ConcurrentBag<Usage>();

    await Parallel.ForEachAsync(await tenants, async (tenant) =>
    {
        //Generate request
        RestRequest request = new RestRequest("tenants/{tenantID}/usages", Method.Get);
        request.AddParameter("tenantID", tenant.id, ParameterType.UrlSegment);
        request.AddHeader("Authorization", $"Bearer {Token.access_token}");

        //Get response
        RestResponse response = await _client.ExecuteAsync(request).ConfigureAwait(false);

        //Validate response
        if (response.StatusCode != HttpStatusCode.OK)
            throw new Exception("Failed at Getting usages for a tenant: ");

        //Add to list
        var t_usage = JsonConvert.DeserializeObject<Wrapper<Usage>>(response.Content);
        usages.AddRange(t_usage.items);
    });

    return usages;
}

.Net 6 之前的版本

public async Task<ConcurrentBag<Usage>> GetUsagesAsync2(Task<List<Tenant>> tenants)
{
    ConcurrentBag<Usage> usages = new ConcurrentBag<Usage>();
    var tasks = new List<Task>();

    foreach (var tenant in await tenants)
    {
        tasks.Add(Task.Run(async () =>
        {
            //Generate request
            RestRequest request = new RestRequest("tenants/{tenantID}/usages", Method.Get);
            request.AddParameter("tenantID", tenant.id, ParameterType.UrlSegment);
            request.AddHeader("Authorization", $"Bearer {Token.access_token}");

            //Get response
            RestResponse response = await _client.ExecuteAsync(request)
                .ConfigureAwait(false);

            //Validate response
            if (response.StatusCode != HttpStatusCode.OK)
                throw new Exception("Failed at Getting usages for a tenant: ");

            //Add to list
            var t_usage = JsonConvert.DeserializeObject<Wrapper<Usage>>(response.Content);
            usages.AddRange(t_usage.items);
        }));
    }

    await Task.WhenAll(tasks);

    return usages;
}

请注意，List 已更改为 ConcurrentBag，因为它不是线程安全的