46c2a0801f
This should address #663, by re-inserting type checking in the transactor stack after the entry point used by the term builder. Before this commit, we were using an SQLite UNIQUE index to assert that no `[e a]` pair, with `a` a cardinality one attribute, was asserted more than once. However, that's not in line with Datomic, which treats transaction inputs as a set and allows a single datom like `[e a v]` to appear multiple times. It's both awkward and not particularly efficient to look for _distinct_ repetitions in SQL, so we accept some runtime cost in order to check for repetitions in the transactor. This will allow us to address #532, which is really about whether we treat inputs as sets. A side benefit is that we can provide more helpful error messages when the transactor does detect that the input truly violates the cardinality constraints of the schema. This commit builds a trie while error checking and collecting final terms, which should be fairly efficient. It also allows a simpler expression of input-provided :db/txInstant datoms, which in turn uncovered a small issue with the transaction watcher, where-by the watcher would not see non-input-provided :db/txInstant datoms. This transition to Datomic-like input-as-set semantics allows us to address #532. Previously, two tempids that upserted to the same entid would produce duplicate datoms, and that would have been rejected by the transactor -- correctly, since we did not allow duplicate datoms under the input-as-list semantics. With input-as-set semantics, duplicate datoms are allowed; and that means that we must allow tempids to be equivalent, i.e., to resolve to the same tempid. To achieve this, we: - index the set of tempids - identify tempid indices that share an upsert - map tempids to a dense set of contiguous integer labels We use the well-known union-find algorithm, as implemented by petgraph, to efficiently manage the set of equivalent tempids. Along the way, I've fixed and added tests for two small errors in the transactor. First, don't drop datoms resolved by upsert (#679). Second, ensure that complex upserts are allocated. I don't know quite what happened here. The Clojure implementation correctly kept complex upserts that hadn't resolved as complex upserts (see9a9dfb502a/src/common/datomish/transact.cljc (L436)) and then allocated complex upserts if they didn't resolve (see9a9dfb502a/src/common/datomish/transact.cljc (L509)). Based on the code comments, I think the Rust implementation must have incorrectly tried to optimize by handling all complex upserts in at most a single generation of evolution, and that's just not correct. We're effectively implementing a topological sort, using very specific domain knowledge, and its not true that a node in a topological sort can be considered only once!
85 lines
3.1 KiB
Rust
85 lines
3.1 KiB
Rust
// Copyright 2018 Mozilla
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
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// this file except in compliance with the License. You may obtain a copy of the
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// License at http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed
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// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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// CONDITIONS OF ANY KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations under the License.
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use std::collections::{
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BTreeSet,
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BTreeMap,
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};
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use mentat_core::{
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Entid,
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TypedValue,
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ValueType,
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};
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use errors::{
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CardinalityConflict,
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};
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use internal_types::{
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AEVTrie,
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};
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/// Map from found [e a v] to expected type.
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pub(crate) type TypeDisagreements = BTreeMap<(Entid, Entid, TypedValue), ValueType>;
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/// Ensure that the given terms type check.
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///
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/// We try to be maximally helpful by yielding every malformed datom, rather than only the first.
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/// In the future, we might change this choice, or allow the consumer to specify the robustness of
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/// the type checking desired, since there is a cost to providing helpful diagnostics.
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pub(crate) fn type_disagreements<'schema>(aev_trie: &AEVTrie<'schema>) -> TypeDisagreements {
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let mut errors: TypeDisagreements = TypeDisagreements::default();
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for (&(a, attribute), evs) in aev_trie {
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for (&e, ref ars) in evs {
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for v in ars.add.iter().chain(ars.retract.iter()) {
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if attribute.value_type != v.value_type() {
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errors.insert((e, a, v.clone()), attribute.value_type);
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}
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}
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}
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}
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errors
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}
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/// Ensure that the given terms obey the cardinality restrictions of the given schema.
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///
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/// That is, ensure that any cardinality one attribute is added with at most one distinct value for
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/// any specific entity (although that one value may be repeated for the given entity).
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/// It is an error to:
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///
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/// - add two distinct values for the same cardinality one attribute and entity in a single transaction
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/// - add and remove the same values for the same attribute and entity in a single transaction
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///
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/// We try to be maximally helpful by yielding every malformed set of datoms, rather than just the
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/// first set, or even the first conflict. In the future, we might change this choice, or allow the
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/// consumer to specify the robustness of the cardinality checking desired.
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pub(crate) fn cardinality_conflicts<'schema>(aev_trie: &AEVTrie<'schema>) -> Vec<CardinalityConflict> {
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let mut errors = vec![];
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for (&(a, attribute), evs) in aev_trie {
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for (&e, ref ars) in evs {
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if !attribute.multival && ars.add.len() > 1 {
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let vs = ars.add.clone();
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errors.push(CardinalityConflict::CardinalityOneAddConflict { e, a, vs });
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}
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let vs: BTreeSet<_> = ars.retract.intersection(&ars.add).cloned().collect();
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if !vs.is_empty() {
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errors.push(CardinalityConflict::AddRetractConflict { e, a, vs })
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}
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}
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}
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errors
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}
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