GZipStream 在 CopyToAsync 的目的地时不调用底层流 *Async 方法

Question

对 GZipStream 使用以下构造，当 GZipStream 是 CopyToAsync 的目标时，它似乎永远不会调用我的自定义流的 *Async 方法。

using (var fs = new System.IO.FileStream(@"C:\BTR\Source\Assemblies\BTR.Rbl.Evolution.Documents.dll", 
        System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.None, 8192, true))
{
    using (var ss = new GZipStream(new MyCustomStream(), CompressionMode.Compress))
    {
        await fs.CopyToAsync(ss);
    }
}

好像只能调用BeginWrite/EndWrite机制。有没有一种方法可以从 GZipStream 派生使其调用 WriteAsync 而不是这样我的自定义流就不必同时实现 WriteAsync 方法和 BeginWrite/EndWrite 方法？

您可以找到此 here

的工作样本

更新：调用初始 Write() 方法时的调用堆栈

SampleStream.Write(buffer, offset, count)
System.IO.Compression.DeflateStream.DoMaintenance(array, offset, count)
System.IO.Compression.DeflateStream.InternalWrite(array, offset, count, isAsync)
System.Runtime.Remoting.Messaging.StackBuilderSink.AsyncProcessMessage(msg, replySink)
System.Runtime.Remoting.Proxies.AgileAsyncWorkerItem.ThreadPoolCallBack(o)
System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(state)
System.Threading.ExecutionContext.RunInternal(executionContext, callback, state, preserveSyncCtx)
System.Threading.ExecutionContext.Run(executionContext, callback, state, preserveSyncCtx)
System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem()
System.Threading._ThreadPoolWaitCallback.PerformWaitCallback()
(Unmanaged code)

Answer 1

您的自定义流实施 BeginWrite/EndWrite（以及 BeginRead/EndRead）会更正确。如果你用我的 AsyncEx.Tasks library:

就不难了

public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count,
    AsyncCallback callback, object state)
{
  var task = WriteAsync(buffer, offset, count);
  return ApmAsyncFactory.ToBegin(task, callback, state);
}

public override void EndWrite(IAsyncResult asyncResult)
{
  ApmAsyncFactory.ToEnd(asyncResult);
}

（ApmAsyncFactory 已添加到 AsyncEx.Tasks 的 1.2.0-alpha-01 版本中）。

GZipStream 在 CopyToAsync 的目的地时不调用底层流 *Async 方法

GZipStream does not call underlying streams *Async methods when destination of CopyToAsync

c#

gzipstream

async-await