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Do not set LSN for new FPI page (#1657)

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* Do not set LSN for new FPI page

refer #1656

* Add page_is_new, page_get_lsn, page_set_lsn functions

* Fix page_is_new implementation

* Add comment from XLogReadBufferForRedoExtended
This commit is contained in:
Konstantin Knizhnik
2022-05-11 15:23:17 +03:00
committed by GitHub
parent d710dff975
commit e6e883eb12
2 changed files with 28 additions and 2 deletions
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19
libs/postgres_ffi/src/lib.rs
View File

@@ -8,6 +8,7 @@
#![allow(deref_nullptr)]
use serde::{Deserialize, Serialize};
use utils::lsn::Lsn;
include!(concat!(env!("OUT_DIR"), "/bindings.rs"));
@@ -37,3 +38,21 @@ pub const fn transaction_id_precedes(id1: TransactionId, id2: TransactionId) ->
let diff = id1.wrapping_sub(id2) as i32;
diff < 0
}
// Check if page is not yet initialized (port of Postgres PageIsInit() macro)
pub fn page_is_new(pg: &[u8]) -> bool {
pg[14] == 0 && pg[15] == 0 // pg_upper == 0
}
// ExtractLSN from page header
pub fn page_get_lsn(pg: &[u8]) -> Lsn {
Lsn(
((u32::from_le_bytes(pg[0..4].try_into().unwrap()) as u64) << 32)
| u32::from_le_bytes(pg[4..8].try_into().unwrap()) as u64,
)
}
pub fn page_set_lsn(pg: &mut [u8], lsn: Lsn) {
pg[0..4].copy_from_slice(&((lsn.0 >> 32) as u32).to_le_bytes());
pg[4..8].copy_from_slice(&(lsn.0 as u32).to_le_bytes());
}

11
pageserver/src/walingest.rs
View File

@@ -24,6 +24,7 @@
use anyhow::Context;
use postgres_ffi::nonrelfile_utils::clogpage_precedes;
use postgres_ffi::nonrelfile_utils::slru_may_delete_clogsegment;
use postgres_ffi::{page_is_new, page_set_lsn};
use anyhow::Result;
use bytes::{Buf, Bytes, BytesMut};
@@ -304,8 +305,14 @@ impl<'a, R: Repository> WalIngest<'a, R> {
image.resize(image.len() + blk.hole_length as usize, 0u8);
image.unsplit(tail);
}
image[0..4].copy_from_slice(&((lsn.0 >> 32) as u32).to_le_bytes());
image[4..8].copy_from_slice(&(lsn.0 as u32).to_le_bytes());
//
// Match the logic of XLogReadBufferForRedoExtended:
// The page may be uninitialized. If so, we can't set the LSN because
// that would corrupt the page.
//
if !page_is_new(&image) {
page_set_lsn(&mut image, lsn)
}
assert_eq!(image.len(), pg_constants::BLCKSZ as usize);
self.put_rel_page_image(modification, rel, blk.blkno, image.freeze())?;
} else {