54 lines
1.8 KiB
Rust
54 lines
1.8 KiB
Rust
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// 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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// A trivial interface for extracting information from a transact as it happens.
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// We have two situations in which we need to do this:
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//
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// - InProgress and Conn both have attribute caches. InProgress's is different from Conn's,
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// because it needs to be able to roll back. These wish to see changes in a certain set of
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// attributes in order to synchronously update the cache during a write.
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// - When observers are registered we want to flip some flags as writes occur so that we can
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// notifying them outside the transaction.
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use mentat_core::{
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Entid,
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Schema,
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TypedValue,
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};
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use mentat_tx::entities::{
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OpType,
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};
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use errors::{
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Result,
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};
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pub trait TransactWatcher {
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fn datom(&mut self, op: OpType, e: Entid, a: Entid, v: &TypedValue);
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/// Only return an error if you want to interrupt the transact!
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/// Called with the schema _prior to_ the transact -- any attributes or
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/// attribute changes transacted during this transact are not reflected in
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/// the schema.
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fn done(&mut self, schema: &Schema) -> Result<()>;
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}
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pub struct NullWatcher();
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impl TransactWatcher for NullWatcher {
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fn datom(&mut self, _op: OpType, _e: Entid, _a: Entid, _v: &TypedValue) {
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}
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fn done(&mut self, _schema: &Schema) -> Result<()> {
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Ok(())
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}
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}
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