// Omitting the required imports.

void[] ptr;

void main() {
    uint buffer;
    glCreateBuffers(1, &buffer);
    // Filling the buffer with data and such...
    ptr = glMapNamedBufferRange(buffer, 0, 512, GL_MAP_WRITE_BIT | GL_MAP_PERSISTENT_BIT | GL_MAP_COHERENT)[0 .. 512];
}

So the question is: Will the GC scan ptr? As you can see, it is a write-only pointer, so reading from it will cause undefined behavior (such as return data which looks like a pointer to data..), and can potentially be reallly slow.

Do I have to mark it with NO_SCAN each time I call glMapNamedBufferRange?

On 24.04.2016 13:03, Lass Safin wrote:
> // Omitting the required imports.
>
> void[] ptr;
>
> void main() {
>      uint buffer;
>      glCreateBuffers(1, &buffer);
>      // Filling the buffer with data and such...
>      ptr = glMapNamedBufferRange(buffer, 0, 512, GL_MAP_WRITE_BIT |
> GL_MAP_PERSISTENT_BIT | GL_MAP_COHERENT)[0 .. 512];
> }
>
> So the question is: Will the GC scan ptr?
[...]
> Do I have to mark it with NO_SCAN each time I call glMapNamedBufferRange?

I don't think so. The GC generally doesn't care about heap memory that's not been allocated through it. As I understand it, you'd have to state explicitly that that memory should be scanned.

On Sunday, 24 April 2016 at 11:03:11 UTC, Lass Safin wrote:
>
> So the question is: Will the GC scan ptr? As you can see, it is a write-only pointer, so reading from it will cause undefined behavior (such as return data which looks like a pointer to data..), and can potentially be reallly slow.

The GC will see that ptr doesn't point to memory managed by the GC and move on.

> Do I have to mark it with NO_SCAN each time I call glMapNamedBufferRange?

No, calling setAttr on memory not managed by the GC will do nothing.