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Evict and retry if the block hash map is full

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I made this change to one the is_write==true case earlier already, but
the is_write==false codepath needs the same treatment.
This commit is contained in:
Heikki Linnakangas
2025-07-30 21:48:25 +03:00
parent 688990e7ec
commit c0360644a7
1 changed files with 29 additions and 25 deletions
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54
pgxn/neon/communicator/src/integrated_cache.rs
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@@ -477,39 +477,43 @@ impl<'t> IntegratedCacheWriteAccess<'t> {
// FIXME: unpin the block entry on error
// Update the block entry
let entry = self.block_map.entry(key.clone());
assert_eq!(found_existing, matches!(entry, Entry::Occupied(_)));
match entry {
Entry::Occupied(e) => {
let block_entry = e.get();
// Update the cache block
let old_blk = block_entry.cache_block.compare_exchange(
INVALID_CACHE_BLOCK,
cache_block,
Ordering::Relaxed,
Ordering::Relaxed,
);
assert!(old_blk == Ok(INVALID_CACHE_BLOCK) || old_blk == Err(cache_block));
loop {
let entry = self.block_map.entry(key.clone());
assert_eq!(found_existing, matches!(entry, Entry::Occupied(_)));
match entry {
Entry::Occupied(e) => {
let block_entry = e.get();
// Update the cache block
let old_blk = block_entry.cache_block.compare_exchange(
INVALID_CACHE_BLOCK,
cache_block,
Ordering::Relaxed,
Ordering::Relaxed,
);
assert!(old_blk == Ok(INVALID_CACHE_BLOCK) || old_blk == Err(cache_block));
block_entry.lw_lsn.store(lw_lsn);
block_entry.lw_lsn.store(lw_lsn);
block_entry.referenced.store(true, Ordering::Relaxed);
block_entry.referenced.store(true, Ordering::Relaxed);
let pin_count = block_entry.pinned.fetch_sub(1, Ordering::Relaxed);
assert!(pin_count > 0);
}
Entry::Vacant(e) => {
// FIXME: what to do if we run out of memory? Evict other relation entries? Remove
// block entries first?
_ = e
.insert(BlockEntry {
let pin_count = block_entry.pinned.fetch_sub(1, Ordering::Relaxed);
assert!(pin_count > 0);
break;
}
Entry::Vacant(e) => {
if let Ok(_) = e.insert(BlockEntry {
lw_lsn: AtomicLsn::new(lw_lsn.0),
cache_block: AtomicU64::new(cache_block),
pinned: AtomicU64::new(0),
referenced: AtomicBool::new(true),
})
.expect("out of memory");
}) {
break;
} else {
// The hash map was full. Evict an entry and retry.
}
}
}
self.try_evict_block_entry();
}
} else {
// !is_write