Feature Request? Viewing []Bytes as a single Bytes about bytes HOT 6 CLOSED

Bytes always stores all of its data as a single contiguous slice. So, are you asking for a way to easily allocate a new buffer and copy all the bytes into it?

Or do you mean combine without allocation? In that case, perhaps you'd want to reach for an impl Buf, which doesn't promise to be a single contiguous slice. A simple one exists within the crate, Chain. But new ones can be implemented too.

If you mean a 3rd option of combining specifically in Bytes, but without an allocation, I don't see how that could be possible.

from bytes.

@seanmonstar I meant combine without allocation, so I think Chain is what I'm looking for!

However, re: the 3rd option,

Say I have a big BytesMut that I am splitting off into smaller blocks. At some point I want to grab a range that might span over multiple blocks.

Now, say I have those blocks, I can order them, so technically underneath the hood they are all part of the same contiguous chunk. In this case, would it be feasible to create a Bytes by using the pointer information from the first and last block?

from bytes.

It might be possible, but not with the methods exposed today. And I wouldn't recommend depending on the internal details to do it externally.

from bytes.

The bytes crate has an unsplit method.

I don't think we can otherwise support this, so I will close the feature request.

from bytes.

@seanmonstar definitely, I wouldn't try to hack that together externally.

But I was thinking about how with try_reclaim and unsplit, the original BytesMut is able to know that the reclaimed memory has no more references, so in the other direction would you be able to create a Bytes from the allocated memory space.

(@Darksonn I was hoping to just articulate the idea a bit more, so sorry to comment on a closed issue)

Basically, if I had an imaginary api like:

impl BytesMut {
  fn view_allocated(&self, offset: usize, len: usize) -> Option<Bytes>;
}

Would the owning BytesMut be able to know that all bytes along that range were frozen, such that returning a Bytes for that range would be safe.

from bytes.

No, BytesMut does not know which regions are frozen and which are part of a BytesMut.

from bytes.