merge volatile and memoized queries

src/lib.rs

@@ -19,7 +19,6 @@ use std::hash::Hash;
 pub mod input;
 pub mod memoized;
 pub mod runtime;
-pub mod volatile;
 
 /// The base trait which your "query context" must implement. Gives
 /// access to the salsa runtime, which you must embed into your query
@@ -428,7 +427,7 @@ macro_rules! query_group {
     (
         @storage_ty[$DB:ident, $Self:ident, volatile]
     ) => {
-        $crate::volatile::VolatileStorage<$DB, $Self>
+        $crate::memoized::VolatileStorage<$DB, $Self>
     };
 
     (

src/memoized.rs

@@ -31,6 +31,11 @@ pub type MemoizedStorage<DB, Q> = WeakMemoizedStorage<DB, Q, AlwaysMemoizeValue>
 /// storage requirements.
 pub type DependencyStorage<DB, Q> = WeakMemoizedStorage<DB, Q, NeverMemoizeValue>;
 
+/// "Dependency" queries just track their dependencies and not the
+/// actual value (which they produce on demand). This lessens the
+/// storage requirements.
+pub type VolatileStorage<DB, Q> = WeakMemoizedStorage<DB, Q, VolatileValue>;
+
 pub struct WeakMemoizedStorage<DB, Q, MP>
 where
     Q: QueryFunction<DB>,
@@ -47,6 +52,8 @@ where
     DB: Database,
 {
     fn should_memoize_value(key: &Q::Key) -> bool;
+
+    fn is_volatile(key: &Q::Key) -> bool;
 }
 
 pub enum AlwaysMemoizeValue {}
@@ -58,6 +65,10 @@ where
     fn should_memoize_value(_key: &Q::Key) -> bool {
         true
     }
+
+    fn is_volatile(_key: &Q::Key) -> bool {
+        false
+    }
 }
 
 pub enum NeverMemoizeValue {}
@@ -69,6 +80,25 @@ where
     fn should_memoize_value(_key: &Q::Key) -> bool {
         false
     }
+
+    fn is_volatile(_key: &Q::Key) -> bool {
+        false
+    }
+}
+
+pub enum VolatileValue {}
+impl<DB, Q> MemoizationPolicy<DB, Q> for VolatileValue
+where
+    Q: QueryFunction<DB>,
+    DB: Database,
+{
+    fn should_memoize_value(_key: &Q::Key) -> bool {
+        false
+    }
+
+    fn is_volatile(_key: &Q::Key) -> bool {
+        true
+    }
 }
 
 /// Defines the "current state" of query's memoized results.
@@ -97,6 +127,7 @@ where
     /// The result of the query, if we decide to memoize it.
     value: Option<Q::Value>,
 
+    /// The inputs that went into our query, if we are tracking them.
     inputs: QueryDescriptorSet<DB>,
 
     /// Last time that we checked our inputs to see if they have
@@ -202,12 +233,16 @@ where
 
         // Query was not previously executed, or value is potentially
         // stale, or value is absent. Let's execute!
-        let (mut stamped_value, inputs) =
-            db.salsa_runtime()
-                .execute_query_implementation(descriptor, || {
-                    debug!("{:?}({:?}): executing query", Q::default(), key);
-                    Q::execute(db, key.clone())
-                });
+        let runtime = db.salsa_runtime();
+        let (mut stamped_value, inputs) = runtime.execute_query_implementation(descriptor, || {
+            debug!("{:?}({:?}): executing query", Q::default(), key);
+
+            if self.is_volatile(key) {
+                runtime.report_untracked_read();
+            }
+
+            Q::execute(db, key.clone())
+        });
 
         // We assume that query is side-effect free -- that is, does
         // not mutate the "inputs" to the query system. Sanity check
@@ -270,6 +305,10 @@ where
     fn should_memoize_value(&self, key: &Q::Key) -> bool {
         MP::should_memoize_value(key)
     }
+
+    fn is_volatile(&self, key: &Q::Key) -> bool {
+        MP::is_volatile(key)
+    }
 }
 
 impl<DB, Q, MP> QueryStorageOps<DB, Q> for WeakMemoizedStorage<DB, Q, MP>

src/volatile.rs

@@ -1,99 +0,0 @@
-use crate::runtime::ChangedAt;
-use crate::runtime::QueryDescriptorSet;
-use crate::runtime::Revision;
-use crate::runtime::StampedValue;
-use crate::CycleDetected;
-use crate::Database;
-use crate::QueryFunction;
-use crate::QueryStorageOps;
-use crate::QueryTable;
-use log::debug;
-use parking_lot::Mutex;
-use rustc_hash::FxHashSet;
-use std::any::Any;
-use std::cell::RefCell;
-use std::collections::hash_map::Entry;
-use std::fmt::Debug;
-use std::fmt::Display;
-use std::fmt::Write;
-use std::hash::Hash;
-
-/// Volatile Storage is just **always** considered dirty. Any time you
-/// ask for the result of such a query, it is recomputed.
-pub struct VolatileStorage<DB, Q>
-where
-    Q: QueryFunction<DB>,
-    DB: Database,
-{
-    /// We don't store the results of volatile queries,
-    /// but we track in-progress set to detect cycles.
-    in_progress: Mutex<FxHashSet<Q::Key>>,
-}
-
-impl<DB, Q> Default for VolatileStorage<DB, Q>
-where
-    Q: QueryFunction<DB>,
-    DB: Database,
-{
-    fn default() -> Self {
-        VolatileStorage {
-            in_progress: Mutex::new(FxHashSet::default()),
-        }
-    }
-}
-
-impl<DB, Q> QueryStorageOps<DB, Q> for VolatileStorage<DB, Q>
-where
-    Q: QueryFunction<DB>,
-    DB: Database,
-{
-    fn try_fetch<'q>(
-        &self,
-        db: &'q DB,
-        key: &Q::Key,
-        descriptor: &DB::QueryDescriptor,
-    ) -> Result<Q::Value, CycleDetected> {
-        if !self.in_progress.lock().insert(key.clone()) {
-            return Err(CycleDetected);
-        }
-
-        let runtime = db.salsa_runtime();
-
-        let (StampedValue { value, changed_at }, inputs) =
-            runtime.execute_query_implementation(descriptor, || {
-                debug!("{:?}({:?}): executing query", Q::default(), key);
-                runtime.report_untracked_read();
-                Q::execute(db, key.clone())
-            });
-
-        assert!(changed_at == ChangedAt::Revision(db.salsa_runtime().current_revision()));
-        assert!(match inputs {
-            QueryDescriptorSet::Untracked => true,
-            _ => false,
-        });
-
-        let was_in_progress = self.in_progress.lock().remove(key);
-        assert!(was_in_progress);
-
-        db.salsa_runtime().report_query_read(descriptor, changed_at);
-
-        Ok(value)
-    }
-
-    fn maybe_changed_since(
-        &self,
-        _db: &'q DB,
-        revision: Revision,
-        key: &Q::Key,
-        _descriptor: &DB::QueryDescriptor,
-    ) -> bool {
-        debug!(
-            "{:?}({:?})::maybe_changed_since(revision={:?}) ==> true (volatile)",
-            Q::default(),
-            key,
-            revision,
-        );
-
-        true
-    }
-}