rust/neon
1
0
Fork 0
mirror of https://github.com/neondatabase/neon.git synced 2026-05-30 03:20:36 +00:00
Code Issues Packages Projects Releases Wiki Activity

Fix comparison routines of OpenSegEntry

Browse Source 
Commit 66929ad6fb added a 'generation' number to open segments stored
in the layer map, to distinguish old layers from layers that were
added to the map during checkpoint processing. But it neglected the
OpenSegEntry::cmp() function.

It seems that the cmp() function is never used by BinaryHeap, so this
didn't cause any user-visible bugs (I tried adding a panic() to the
cmp() function and it didn't fire). But it's clearly wrong and we need
to fix it, anyway.
This commit is contained in:
Heikki Linnakangas
2021-09-07 17:49:15 +03:00
parent 292bdaa6a7
commit 9098f2159d
1 changed files with 9 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
pageserver/src/layered_repository/layer_map.rs
View File

@@ -62,37 +62,33 @@ struct SegEntry {
}
/// Entry held LayerMap.open_segs, with boilerplate comparison
/// routines to implement a min-heap ordered by 'oldest_pending_lsn'
/// routines to implement a min-heap ordered by 'oldest_pending_lsn' and 'generation''
///
/// Each entry also carries a generation number. It can be used to distinguish
/// entries with the same 'oldest_pending_lsn'.
struct OpenSegEntry {
pub oldest_pending_lsn: Lsn,
pub layer: Arc<InMemoryLayer>,
pub generation: u64,
pub layer: Arc<InMemoryLayer>,
}
impl Ord for OpenSegEntry {
fn cmp(&self, other: &Self) -> Ordering {
// BinaryHeap is a max-heap, and we want a min-heap. Reverse the ordering here
// to get that.
other.oldest_pending_lsn.cmp(&self.oldest_pending_lsn)
// to get that. Entries with identical oldest_pending_lsn are ordered by generation
other
.oldest_pending_lsn
.cmp(&self.oldest_pending_lsn)
.then_with(|| other.generation.cmp(&self.generation))
}
}
impl PartialOrd for OpenSegEntry {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
// BinaryHeap is a max-heap, and we want a min-heap. Reverse the ordering here
// to get that. Entries with identical oldest_pending_lsn are ordered by generation
Some(
other
.oldest_pending_lsn
.cmp(&self.oldest_pending_lsn)
.then_with(|| other.generation.cmp(&self.generation)),
)
Some(self.cmp(other))
}
}
impl PartialEq for OpenSegEntry {
fn eq(&self, other: &Self) -> bool {
self.oldest_pending_lsn.eq(&other.oldest_pending_lsn)
self.cmp(&other) == Ordering::Equal
}
}
impl Eq for OpenSegEntry {}