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OpHeadsStore: when merging ops, also remove ancestor op from disk early

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This is more code, but I think it's clearer because the code for
removing the ancestors from the set of parents and from disk is now
close. I hope this will also help prepare for some further changes.
This commit is contained in:
Martin von Zweigbergk 2021-03-11 23:30:06 -08:00
parent d4c39d399f
commit eac0c9f579
1 changed files with 21 additions and 12 deletions
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33
lib/src/op_heads_store.rs
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@ -25,6 +25,7 @@ use std::path::PathBuf;
use std::sync::Arc;
use crate::store::CommitId;
use std::collections::HashSet;
use thiserror::Error;
/// Manages the very set of current heads of the operation log. The store is
@ -153,24 +154,32 @@ impl OpHeadsStore {
Operation::new(op_store.clone(), op_id.clone(), data)
})
.collect();
let op_heads = self.handle_ancestor_ops(op_heads);
let (merge_operation_id, merge_operation, merged_view) =
merge_op_heads(store, op_store, index_store, op_heads)?;
self.add_op_head(&merge_operation_id);
for old_op_head_id in &merge_operation.parents {
self.remove_op_head(old_op_head_id);
}
Ok((merge_operation_id, merge_operation, merged_view))
}
/// Removes operations in the input that are ancestors of other operations
/// in the input. The ancestors are removed both from the list and from
/// disk.
fn handle_ancestor_ops(&self, op_heads: Vec<Operation>) -> Vec<Operation> {
let op_head_ids_before: HashSet<_> = op_heads.iter().map(|op| op.id().clone()).collect();
let neighbors_fn = |op: &Operation| op.parents();
// Remove ancestors so we don't create merge operation with an operation and its
// ancestor
let op_heads =
dag_walk::unreachable(op_heads, &neighbors_fn, &|op: &Operation| op.id().clone());
let op_heads: Vec<_> = op_heads.into_iter().collect();
let (merge_operation_id, merge_operation, merged_view) =
merge_op_heads(store, op_store, index_store, op_heads)?;
self.add_op_head(&merge_operation_id);
for old_op_head_id in op_head_ids {
// The merged one will be in the input to the merge if it's a "fast-forward"
// merge.
if old_op_head_id != merge_operation_id {
self.remove_op_head(&old_op_head_id);
}
let op_head_ids_after: HashSet<_> = op_heads.iter().map(|op| op.id().clone()).collect();
for removed_op_head in op_head_ids_before.difference(&op_head_ids_after) {
self.remove_op_head(&removed_op_head);
}
Ok((merge_operation_id, merge_operation, merged_view))
op_heads.into_iter().collect()
}
}