sqlx_postgres/message/
data_row.rsuse byteorder::{BigEndian, ByteOrder};
use sqlx_core::bytes::Bytes;
use std::ops::Range;
use crate::error::Error;
use crate::message::{BackendMessage, BackendMessageFormat};
#[derive(Debug)]
pub struct DataRow {
pub(crate) storage: Bytes,
pub(crate) values: Vec<Option<Range<u32>>>,
}
impl DataRow {
#[inline]
pub(crate) fn get(&self, index: usize) -> Option<&'_ [u8]> {
self.values[index]
.as_ref()
.map(|col| &self.storage[(col.start as usize)..(col.end as usize)])
}
}
impl BackendMessage for DataRow {
const FORMAT: BackendMessageFormat = BackendMessageFormat::DataRow;
fn decode_body(buf: Bytes) -> Result<Self, Error> {
if buf.len() < 2 {
return Err(err_protocol!(
"expected at least 2 bytes, got {}",
buf.len()
));
}
let cnt = BigEndian::read_u16(&buf) as usize;
let mut values = Vec::with_capacity(cnt);
let mut offset: u32 = 2;
for _ in 0..cnt {
let value_start = offset
.checked_add(4)
.ok_or_else(|| err_protocol!("next value start out of range (offset: {offset})"))?;
if (buf.len() as u64) < (value_start as u64) {
return Err(err_protocol!(
"expected 4 bytes at offset {offset}, got {}",
(value_start as u64) - (buf.len() as u64)
));
}
#[allow(clippy::cast_possible_truncation)]
let length = BigEndian::read_i32(&buf[(offset as usize)..]);
if let Ok(length) = u32::try_from(length) {
let value_end = value_start.checked_add(length).ok_or_else(|| {
err_protocol!("value_start + length out of range ({offset} + {length})")
})?;
values.push(Some(value_start..value_end));
offset = value_end;
} else {
values.push(None);
offset = value_start;
}
}
Ok(Self {
storage: buf,
values,
})
}
}
#[test]
fn test_decode_data_row() {
const DATA: &[u8] = b"\
\x00\x08\
\xff\xff\xff\xff\
\x00\x00\x00\x04\
\x00\x00\x00\n\
\xff\xff\xff\xff\
\x00\x00\x00\x04\
\x00\x00\x00\x14\
\xff\xff\xff\xff\
\x00\x00\x00\x04\
\x00\x00\x00(\
\xff\xff\xff\xff\
\x00\x00\x00\x04\
\x00\x00\x00P";
let row = DataRow::decode_body(DATA.into()).unwrap();
assert_eq!(row.values.len(), 8);
assert!(row.get(0).is_none());
assert_eq!(row.get(1).unwrap(), &[0_u8, 0, 0, 10][..]);
assert!(row.get(2).is_none());
assert_eq!(row.get(3).unwrap(), &[0_u8, 0, 0, 20][..]);
assert!(row.get(4).is_none());
assert_eq!(row.get(5).unwrap(), &[0_u8, 0, 0, 40][..]);
assert!(row.get(6).is_none());
assert_eq!(row.get(7).unwrap(), &[0_u8, 0, 0, 80][..]);
}
#[cfg(all(test, not(debug_assertions)))]
#[bench]
fn bench_data_row_get(b: &mut test::Bencher) {
const DATA: &[u8] = b"\x00\x08\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00\n\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00\x14\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00(\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00P";
let row = DataRow::decode_body(test::black_box(Bytes::from_static(DATA))).unwrap();
b.iter(|| {
let _value = test::black_box(&row).get(3);
});
}
#[cfg(all(test, not(debug_assertions)))]
#[bench]
fn bench_decode_data_row(b: &mut test::Bencher) {
const DATA: &[u8] = b"\x00\x08\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00\n\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00\x14\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00(\xff\xff\xff\xff\x00\x00\x00\x04\x00\x00\x00P";
b.iter(|| {
let _ = DataRow::decode_body(test::black_box(Bytes::from_static(DATA)));
});
}