NativeArray.CopyFrom() strange behavior

Hi, I just found that if I copy one Native array to another with .CopyFrom() it takes low overhead (for 4*1920*1080 it takes 2ms), but if I copy managed array to Native one it takes x10 longer.

But after some debugging I am able to conclude that when coping one native array to another it is not blocking function and after 2ms when my code is continued only small slice of array was been copied. The problem is, how I can know when whole array is copied and ready?

 

Is there any documentation about this?
https://docs.unity3d.com/2018.1/Documentation/ScriptReference/Unity.Collections.NativeArray_1.html

I cannnot find information what I need from this page.

 

It is maybe problem because I run code in editor. But cannot build and run, it crashes every time, but in editor it works, have to see what is problem, but for now I am focused to editor.

I am using AsyncGPUReadback to take screenshot in OnRenderImage callback.
To receive pixels I have:

//global variables
NativeArray<Color32> mbuffer;
NativeArray<Color32> buffer;

//when data is ready
mbuffer = req.GetData<Color32>();
buffer.CopyFrom(mbuffer);

and after that, sending pointer to buffer to native plugin NativeArrayUnsafeUtility.GetUnsafePtr<Color32>(buffer);
but native plugin get uncompleted frame, if it waits some miliseconds, frame is completed.

Second strange thing, if I don't do copy and instead that I send pointer to mbuffer to native plugin, I got all zeros instead rendered pixels!

 

I don't know about what parameters you are talking... This is my async request. I don't have any parameters, just source.

Code (CSharp):

1.  
2. void OnRenderImage(RenderTexture source, RenderTexture destination)
3.     {
4.         if (_requests.Count < 8)
5.             _requests.Enqueue(AsyncGPUReadback.Request(source));
6.         else
7.             UnityEngine.Debug.Log("Too many requests.");
8.  
9.         Graphics.Blit(source, destination);
10.     }
11.  

 

Yes, there is a problem with synchronization. I got done flag on request even if request is not completed.
How many requests could I have in queue? I am trying to take texture only from peek of queue when I have two requests done, but then I got a lot requests with an error.?

 

First, I didn't know I have to fetch the data at the frame it arrives. It is then clear why I had errors. Here is code snippet which doesn't have errors but it has frames which are not complete rendered:

Code (CSharp):

1. while (_requests.Count > 0)
2.             {
3.                 var req = _requests.Peek();
4.  
5.                
6.                 if (req.hasError)
7.                 {
8.                     UnityEngine.Debug.Log("GPU readback error detected.");
9.                     _requests.Dequeue();
10.                 }
11.                 else if (req.done)
12.                 {
13.                                      
14.                     mbuffer = req.GetData<Color32>();
15.  
16.                     buffer[(frameCnt[0]) % 10].CopyFrom(mbuffer);
17.                    
18.  
19.                     frameCnt[0]++;
20.  
21.                     _requests.Dequeue();
22.                 }
23.                 else
24.                 {
25.                     break;
26.                 }
27.             }

Format of my source texture is 1920*1080 but I was not set that from script but from editor game window. Yes, there is equal number of elements.

Will try to make simple example without native plugin to demonstrate the problem.

 

Yes, I am using DX11.
I have installed 18.2 it is nice callback feature but problem is still here. I have new problem, when I press stop in editor, got InvalidOperationException: The NativeArray has been deallocated.... and Unity stopped working. It is probably something with this new callback.. async buffers are deallocated before callback is disabled?

I am still not sure is something wrong with native copy or async request. I have run one test where I have three nativeArray.copy actions one after another, sth like:

mbuffer = req.GetData<Color32>();
buffer[(frameCnt[0]) % 10].CopyFrom(mbuffer);
buffer[(frameCnt[0]) % 10].CopyFrom(nColorRed);
buffer[(frameCnt[0]) % 10].CopyFrom(nColorGreen);

and immediately after that I got this (it was blue color in the buffer before first frame):

 

Tnx for answer, I will.
Is there soulution for second problem: