Reading into BytesMut always returns 0 bytes read

[dharkness]

Reading into BytesMut always returns 0 bytes read

[Thomasdezeeuw]

BytesMut::with_capacity(4096) still creates an empty buffer. So you're effectively passing &[] to the read call.

Try assert_eq!(BytesMut::with_capacity(4096), &[]);. I don't use the bytes crate myself, but the same is true for Vec::with_capacity, you need to use vec![0; 4096] (equivalent) instead. In other words create a zeroed buffer, instead of an uninitialised one.

[Thomasdezeeuw]

You can still use BytesMut. The problem is the std::io::Read trait, it only works with initialised buffers. So you'll have the same problem with Vec.

[dharkness]

Thank you, that makes sense. I thought the point of BytesMut was to create an empty buffer that read() would fill (up to the capacity) on subsequent calls. I'll switch to a vec and give it a go.