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Add safety notes, benchmark. Optimize checksum calculation

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This commit is contained in:
Alexey Kondratov
2022-07-07 19:43:47 +02:00
parent 53b9cb915e
commit 0eca1d19de
12 changed files with 124 additions and 84 deletions
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16
libs/postgres_ffi/src/lib.rs
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@@ -60,13 +60,17 @@ pub fn page_set_lsn(pg: &mut [u8], lsn: Lsn) {
/// Calculate page checksum and stamp it onto the page.
/// NB: this will zero out and ignore any existing checksum.
pub fn page_set_checksum(page: &mut [u8], blkno: u32) {
/// # Safety
/// See safety notes for `pg_checksum_page`
pub unsafe fn page_set_checksum(page: &mut [u8], blkno: u32) {
let checksum = pg_checksum_page(page, blkno);
page[8..10].copy_from_slice(&checksum.to_le_bytes());
}
/// Check if page checksum is valid.
pub fn page_verify_checksum(page: &[u8], blkno: u32) -> bool {
/// # Safety
/// See safety notes for `pg_checksum_page`
pub unsafe fn page_verify_checksum(page: &[u8], blkno: u32) -> bool {
let checksum = pg_checksum_page(page, blkno);
checksum == u16::from_le_bytes(page[8..10].try_into().unwrap())
}
@@ -86,7 +90,7 @@ mod tests {
}
// Calculate the checksum.
let checksum = pg_checksum_page(&page[..], 0);
let checksum = unsafe { pg_checksum_page(&page[..], 0) };
// Sanity check: random bytes in the checksum attribute should not be
// a valid checksum.
@@ -96,12 +100,12 @@ mod tests {
);
// Set the actual checksum.
page_set_checksum(&mut page, 0);
unsafe { page_set_checksum(&mut page, 0) };
// Verify the checksum.
assert!(page_verify_checksum(&page[..], 0));
assert!(unsafe { page_verify_checksum(&page[..], 0) });
// Checksum is not valid with another block number.
assert!(!page_verify_checksum(&page[..], 1));
assert!(!unsafe { page_verify_checksum(&page[..], 1) });
}
}