AsyncEnumerableExtensions.cs z

最新推荐文章于 2024-12-23 14:58:26 发布

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最新推荐文章于 2024-12-23 14:58:26 发布

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本文介绍了一个实用的C#扩展方法，用于异步遍历集合，并支持任务并行处理。通过三种不同的实现方式，展示了如何在异步操作中有效利用观察者模式和任务并行库(Task Parallel Library)来提高程序的执行效率。

public static class Extensions
{
public static async Task ForEachAsync<T, U>(this IEnumerable<T> collection, Func<T, Task<U>> body, IObserver<U> observer = null)
{
foreach (var item in collection)
{
var res = await body(item);
if (null != observer)
{
observer.OnNext(res);
}
}
}
 
public static async Task ForEachAsyncPerformance<T, U>(this IEnumerable<T> collection, Func<T, Task<U>> body, IObserver<U> observer = null)
{
var enumerator = collection.GetEnumerator();
 
Task<U> task = null;
if (enumerator.MoveNext())
{
task = body(enumerator.Current);
}
while (enumerator.MoveNext())
{
var item = enumerator.Current;
var res = await task;
task = body(item);
if (null != observer)
{
observer.OnNext(res);
}
}
if (null != task)
{
var res = await task;
if (null != observer)
{
observer.OnNext(res);
}
}
}
 
public static async Task ForEachAsync<T, U>(this IEnumerable<T> collection, int parallelism, Func<T, Task<U>> body, IObserver<U> observer = null)
{
int inFlight = 0;
var tasks = new HashSet<Task<U>>();
 
foreach (var item in collection)
{
if (inFlight >= parallelism)
{
var task = await Task.WhenAny(tasks);
tasks.Remove(task);
inFlight--;
if (null != observer)
{
observer.OnNext(task.Result);
}
}
 
inFlight++;
tasks.Add(body(item));
}
 
while (inFlight > 0)
{
var task = await Task.WhenAny(tasks);
tasks.Remove(task);
inFlight--;
if (null != observer)
{
observer.OnNext(task.Result);
}
}
}
}