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shardtree: Preserve flags at positions with multiple checkpoints 

If we have a retained checkpoint at the same position and with the same
flags as a pruned checkpoint, we need to preserve the flags on the node.
The flags are cleared when the last of the checkpoints at the position
is removed.

Co-authored-by: Kris Nuttycombe <kris@nutty.land>
This commit is contained in:
Jack Grigg 2023-07-05 21:36:15 +00:00
parent a54f4e198f
commit 1be68e5c64
1 changed files with 41 additions and 18 deletions
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59
shardtree/src/lib.rs
View File

@ -812,17 +812,26 @@ impl<
if checkpoint_count > self.max_checkpoints {
// Batch removals by subtree & create a list of the checkpoint identifiers that
// will be removed from the checkpoints map.
let remove_count = checkpoint_count - self.max_checkpoints;
let mut checkpoints_to_delete = vec![];
let mut clear_positions: BTreeMap<Address, BTreeMap<Position, RetentionFlags>> =
BTreeMap::new();
self.store
.with_checkpoints(
checkpoint_count - self.max_checkpoints,
|cid, checkpoint| {
checkpoints_to_delete.push(cid.clone());
.with_checkpoints(checkpoint_count, |cid, checkpoint| {
// When removing is true, we are iterating through the range of
// checkpoints being removed. When remove is false, we are
// iterating through the range of checkpoints that are being
// retained.
let removing = checkpoints_to_delete.len() < remove_count;
let mut clear_at = |pos, flags_to_clear| {
let subtree_addr = Self::subtree_addr(pos);
if removing {
checkpoints_to_delete.push(cid.clone());
}
let mut clear_at = |pos, flags_to_clear| {
let subtree_addr = Self::subtree_addr(pos);
if removing {
// Mark flags to be cleared from the given position.
clear_positions
.entry(subtree_addr)
.and_modify(|to_clear| {
@ -832,23 +841,37 @@ impl<
.or_insert(flags_to_clear);
})
.or_insert_with(|| BTreeMap::from([(pos, flags_to_clear)]));
};
// clear the checkpoint leaf
if let TreeState::AtPosition(pos) = checkpoint.tree_state {
clear_at(pos, RetentionFlags::CHECKPOINT)
} else {
// Unmark flags that might have been marked for clearing above
// but which we now know we need to preserve.
if let Some(to_clear) = clear_positions.get_mut(&subtree_addr) {
if let Some(flags) = to_clear.get_mut(&pos) {
*flags &= !flags_to_clear;
}
}
}
};
// clear the leaves that have been marked for removal
for unmark_pos in checkpoint.marks_removed.iter() {
clear_at(*unmark_pos, RetentionFlags::MARKED)
}
// Clear or preserve the checkpoint leaf.
if let TreeState::AtPosition(pos) = checkpoint.tree_state {
clear_at(pos, RetentionFlags::CHECKPOINT)
}
Ok(())
},
)
// Clear or preserve the leaves that have been marked for removal.
for unmark_pos in checkpoint.marks_removed.iter() {
clear_at(*unmark_pos, RetentionFlags::MARKED)
}
Ok(())
})
.map_err(ShardTreeError::Storage)?;
// Remove any nodes that are fully preserved by later checkpoints.
clear_positions.retain(|_, to_clear| {
to_clear.retain(|_, flags| !flags.is_empty());
!to_clear.is_empty()
});
trace!(
"Removing checkpoints {:?}, pruning subtrees {:?}",
checkpoints_to_delete,