fn read()

in neqo-transport/src/recv_stream.rs [334:373]

• 35 lines of code
• 6 McCabe index (conditional complexity)

    fn read(&mut self, buf: &mut [u8]) -> usize {
        qtrace!("Reading {} bytes, {} available", buf.len(), self.buffered());
        let mut copied = 0;

        for (&range_start, range_data) in &mut self.data_ranges {
            let mut keep = false;
            if self.retired >= range_start {
                // Frame data has new contiguous bytes.
                let copy_offset = usize::try_from(max(range_start, self.retired) - range_start)
                    .expect("u64 fits in usize");
                assert!(range_data.len() >= copy_offset);
                let available = range_data.len() - copy_offset;
                let space = buf.len() - copied;
                let copy_bytes = if available > space {
                    keep = true;
                    space
                } else {
                    available
                };

                if copy_bytes > 0 {
                    let copy_slc = &range_data[copy_offset..copy_offset + copy_bytes];
                    buf[copied..copied + copy_bytes].copy_from_slice(copy_slc);
                    copied += copy_bytes;
                    self.retired += u64::try_from(copy_bytes).expect("usize fits in u64");
                }
            } else {
                // The data in the buffer isn't contiguous.
                keep = true;
            }
            if keep {
                let mut keep = self.data_ranges.split_off(&range_start);
                mem::swap(&mut self.data_ranges, &mut keep);
                return copied;
            }
        }

        self.data_ranges.clear();
        copied
    }