Move salsa fork in-tree

crates/salsa/src/debug.rs

@@ -0,0 +1,66 @@
+//! Debugging APIs: these are meant for use when unit-testing or
+//! debugging your application but aren't ordinarily needed.
+
+use crate::durability::Durability;
+use crate::plumbing::QueryStorageOps;
+use crate::Query;
+use crate::QueryTable;
+use std::iter::FromIterator;
+
+/// Additional methods on queries that can be used to "peek into"
+/// their current state. These methods are meant for debugging and
+/// observing the effects of garbage collection etc.
+pub trait DebugQueryTable {
+    /// Key of this query.
+    type Key;
+
+    /// Value of this query.
+    type Value;
+
+    /// Returns a lower bound on the durability for the given key.
+    /// This is typically the minimum durability of all values that
+    /// the query accessed, but we may return a lower durability in
+    /// some cases.
+    fn durability(&self, key: Self::Key) -> Durability;
+
+    /// Get the (current) set of the entries in the query table.
+    fn entries<C>(&self) -> C
+    where
+        C: FromIterator<TableEntry<Self::Key, Self::Value>>;
+}
+
+/// An entry from a query table, for debugging and inspecting the table state.
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
+#[non_exhaustive]
+pub struct TableEntry<K, V> {
+    /// key of the query
+    pub key: K,
+    /// value of the query, if it is stored
+    pub value: Option<V>,
+}
+
+impl<K, V> TableEntry<K, V> {
+    pub(crate) fn new(key: K, value: Option<V>) -> TableEntry<K, V> {
+        TableEntry { key, value }
+    }
+}
+
+impl<Q> DebugQueryTable for QueryTable<'_, Q>
+where
+    Q: Query,
+    Q::Storage: QueryStorageOps<Q>,
+{
+    type Key = Q::Key;
+    type Value = Q::Value;
+
+    fn durability(&self, key: Q::Key) -> Durability {
+        self.storage.durability(self.db, &key)
+    }
+
+    fn entries<C>(&self) -> C
+    where
+        C: FromIterator<TableEntry<Self::Key, Self::Value>>,
+    {
+        self.storage.entries(self.db)
+    }
+}