mirror of
https://github.com/salsa-rs/salsa.git
synced 2024-12-04 21:45:55 +00:00
factor out ChangedAt
to record when something changed
This commit is contained in:
parent
4efbd411fa
commit
296d33aae7
4 changed files with 71 additions and 35 deletions
11
src/input.rs
11
src/input.rs
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@ -1,3 +1,4 @@
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use crate::runtime::ChangedAt;
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use crate::runtime::QueryDescriptorSet;
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use crate::runtime::Revision;
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use crate::runtime::StampedValue;
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@ -66,7 +67,7 @@ where
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Ok(StampedValue {
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value: <Q::Value>::default(),
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changed_at: Revision::ZERO,
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changed_at: ChangedAt::Revision(Revision::ZERO),
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})
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}
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}
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@ -109,10 +110,10 @@ where
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map_read
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.get(key)
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.map(|v| v.changed_at)
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.unwrap_or(Revision::ZERO)
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.unwrap_or(ChangedAt::Revision(Revision::ZERO))
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};
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changed_at > revision
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changed_at.changed_since(revision)
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}
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}
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@ -131,7 +132,7 @@ where
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// racing with somebody else to modify this same cell.
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// (Otherwise, someone else might write a *newer* revision
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// into the same cell while we block on the lock.)
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let changed_at = db.salsa_runtime().increment_revision();
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let changed_at = ChangedAt::Revision(db.salsa_runtime().increment_revision());
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map_write.insert(key, StampedValue { value, changed_at });
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}
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@ -150,7 +151,7 @@ where
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// Unlike with `set`, here we use the **current revision** and
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// do not create a new one.
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let changed_at = db.salsa_runtime().current_revision();
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let changed_at = ChangedAt::Revision(db.salsa_runtime().current_revision());
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map_write.insert(key, StampedValue { value, changed_at });
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}
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@ -1,3 +1,4 @@
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use crate::runtime::ChangedAt;
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use crate::runtime::QueryDescriptorSet;
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use crate::runtime::Revision;
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use crate::runtime::StampedValue;
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@ -91,7 +92,7 @@ where
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{
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/// Last time the value has actually changed.
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/// changed_at can be less than verified_at.
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changed_at: Revision,
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changed_at: ChangedAt,
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/// The result of the query, if we decide to memoize it.
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value: Option<Q::Value>,
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@ -184,12 +185,7 @@ where
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// first things first, let's walk over each of our previous
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// inputs and check whether they are out of date.
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if let Some(QueryState::Memoized(old_memo)) = &mut old_value {
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if old_memo.value.is_some() {
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if old_memo
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.inputs
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.iter()
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.all(|old_input| !old_input.maybe_changed_since(db, old_memo.changed_at))
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{
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if old_memo.validate_memoized_value(db) {
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debug!("{:?}({:?}): inputs still valid", Q::default(), key);
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// If none of out inputs have changed since the last time we refreshed
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// our value, then our value must still be good. We'll just patch
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@ -203,7 +199,6 @@ where
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return Ok(StampedValue { value, changed_at });
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}
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}
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}
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// Query was not previously executed, or value is potentially
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// stale, or value is absent. Let's execute!
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@ -318,14 +313,14 @@ where
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// If our memo is still up to date, then check if we've
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// changed since the revision.
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if memo.verified_at == revision_now {
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return memo.changed_at > revision;
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return memo.changed_at.changed_since(revision);
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}
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if memo.value.is_some() {
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// Otherwise, if we cache values, fall back to the full read to compute the result.
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drop(memo);
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drop(map_read);
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return match self.read(db, key, descriptor) {
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Ok(v) => v.changed_at > revision,
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Ok(v) => v.changed_at.changed_since(revision),
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Err(CycleDetected) => true,
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};
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}
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@ -370,7 +365,8 @@ where
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let mut map_write = self.map.write();
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let changed_at = db.salsa_runtime().current_revision();
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let current_revision = db.salsa_runtime().current_revision();
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let changed_at = ChangedAt::Revision(current_revision);
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map_write.insert(
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key,
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@ -378,8 +374,28 @@ where
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value: Some(value),
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changed_at,
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inputs: QueryDescriptorSet::new(),
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verified_at: changed_at,
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verified_at: current_revision,
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}),
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);
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}
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}
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impl<DB, Q> Memo<DB, Q>
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where
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Q: QueryFunction<DB>,
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DB: Database,
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{
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fn validate_memoized_value(&self, db: &DB) -> bool {
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// If we don't have a memoized value, nothing to validate.
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if !self.value.is_some() {
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return false;
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}
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match self.changed_at {
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ChangedAt::Revision(revision) => self
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.inputs
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.iter()
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.all(|old_input| !old_input.maybe_changed_since(db, revision)),
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}
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}
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}
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@ -136,7 +136,7 @@ where
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/// - `descriptor`: the query whose result was read
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/// - `changed_revision`: the last revision in which the result of that
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/// query had changed
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crate fn report_query_read(&self, descriptor: &DB::QueryDescriptor, changed_at: Revision) {
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crate fn report_query_read(&self, descriptor: &DB::QueryDescriptor, changed_at: ChangedAt) {
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if let Some(top_query) = self.local_state.borrow_mut().query_stack.last_mut() {
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top_query.add_read(descriptor, changed_at);
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}
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@ -178,7 +178,7 @@ struct ActiveQuery<DB: Database> {
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descriptor: DB::QueryDescriptor,
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/// Records the maximum revision where any subquery changed
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changed_at: Revision,
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changed_at: ChangedAt,
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/// Each subquery
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subqueries: QueryDescriptorSet<DB>,
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@ -188,12 +188,12 @@ impl<DB: Database> ActiveQuery<DB> {
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fn new(descriptor: DB::QueryDescriptor) -> Self {
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ActiveQuery {
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descriptor,
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changed_at: Revision::ZERO,
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changed_at: ChangedAt::Revision(Revision::ZERO),
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subqueries: QueryDescriptorSet::new(),
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}
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}
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fn add_read(&mut self, subquery: &DB::QueryDescriptor, changed_at: Revision) {
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fn add_read(&mut self, subquery: &DB::QueryDescriptor, changed_at: ChangedAt) {
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self.subqueries.insert(subquery.clone());
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self.changed_at = self.changed_at.max(changed_at);
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}
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@ -214,6 +214,25 @@ impl std::fmt::Debug for Revision {
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}
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}
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/// Records when a stamped value changed.
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///
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/// Note: the order of variants is significant. We sometimes use `max`
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/// for example to find the "most recent revision" when something
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/// changed.
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#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
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pub enum ChangedAt {
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Revision(Revision),
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}
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impl ChangedAt {
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/// True if this value has changed after `revision`.
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pub fn changed_since(self, revision: Revision) -> bool {
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match self {
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ChangedAt::Revision(r) => r > revision,
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}
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}
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}
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/// An insertion-order-preserving set of queries. Used to track the
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/// inputs accessed during query execution.
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crate struct QueryDescriptorSet<DB: Database> {
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@ -249,5 +268,5 @@ impl<DB: Database> QueryDescriptorSet<DB> {
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#[derive(Clone, Debug)]
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crate struct StampedValue<V> {
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crate value: V,
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crate changed_at: Revision,
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crate changed_at: ChangedAt,
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}
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@ -1,3 +1,4 @@
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use crate::runtime::ChangedAt;
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use crate::runtime::Revision;
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use crate::runtime::StampedValue;
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use crate::CycleDetected;
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@ -68,10 +69,9 @@ where
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let was_in_progress = self.in_progress.lock().remove(key);
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assert!(was_in_progress);
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let revision_now = db.salsa_runtime().current_revision();
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let changed_at = ChangedAt::Revision(db.salsa_runtime().current_revision());
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db.salsa_runtime()
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.report_query_read(descriptor, revision_now);
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db.salsa_runtime().report_query_read(descriptor, changed_at);
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Ok(value)
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}
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