new trie

Cargo.toml

@@ -4,13 +4,12 @@ members = [
 	"memory-db",
 	"hash256-std-hasher",
 	"test-support/keccak-hasher",
+	"test-support/mem-tree-db",
 	"test-support/reference-trie",
 	"test-support/trie-standardmap",
 	"test-support/trie-bench",
 	"trie-db",
 	"trie-db/test",
-	"trie-eip1186",
-	"trie-eip1186/test",
 	"trie-root",
 	"trie-root/test"
 ]

hash-db/src/lib.rs

@@ -16,6 +16,11 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+#[cfg(not(feature = "std"))]
+extern crate alloc;
+
+#[cfg(not(feature = "std"))]
+use alloc::vec::Vec;
 #[cfg(not(feature = "std"))]
 use core::hash;
 #[cfg(feature = "std")]
@@ -73,144 +78,19 @@ pub trait Hasher: Sync + Send {
 	fn hash(x: &[u8]) -> Self::Out;
 }
 
-/// Trait modelling a plain datastore whose key is a fixed type.
-/// The caller should ensure that a key only corresponds to
-/// one value.
-pub trait PlainDB<K, V>: Send + Sync + AsPlainDB<K, V> {
-	/// Look up a given hash into the bytes that hash to it, returning None if the
-	/// hash is not known.
-	fn get(&self, key: &K) -> Option<V>;
-
-	/// Check for the existence of a hash-key.
-	fn contains(&self, key: &K) -> bool;
-
-	/// Insert a datum item into the DB. Insertions are counted and the equivalent
-	/// number of `remove()`s must be performed before the data is considered dead.
-	/// The caller should ensure that a key only corresponds to one value.
-	fn emplace(&mut self, key: K, value: V);
-
-	/// Remove a datum previously inserted. Insertions can be "owed" such that the
-	/// same number of `insert()`s may happen without the data being eventually
-	/// being inserted into the DB. It can be "owed" more than once.
-	/// The caller should ensure that a key only corresponds to one value.
-	fn remove(&mut self, key: &K);
-}
-
-/// Trait for immutable reference of PlainDB.
-pub trait PlainDBRef<K, V> {
-	/// Look up a given hash into the bytes that hash to it, returning None if the
-	/// hash is not known.
-	fn get(&self, key: &K) -> Option<V>;
-
-	/// Check for the existance of a hash-key.
-	fn contains(&self, key: &K) -> bool;
-}
-
-impl<'a, K, V> PlainDBRef<K, V> for &'a dyn PlainDB<K, V> {
-	fn get(&self, key: &K) -> Option<V> {
-		PlainDB::get(*self, key)
-	}
-	fn contains(&self, key: &K) -> bool {
-		PlainDB::contains(*self, key)
-	}
-}
+/// Trait modelling datastore keyed by a hash defined by the `Hasher` and optional location tag.
+pub trait HashDB<H: Hasher, T, L>: Send + Sync {
+	/// Look up a trie node by hash and location.
+	/// Returns the node bytes and the list of children node locations if any.
+	fn get(&self, key: &H::Out, prefix: Prefix, location: L) -> Option<(T, Vec<L>)>;
 
-impl<'a, K, V> PlainDBRef<K, V> for &'a mut dyn PlainDB<K, V> {
-	fn get(&self, key: &K) -> Option<V> {
-		PlainDB::get(*self, key)
+	/// Check for the existence of a hash-key at the location.
+	fn contains(&self, key: &H::Out, prefix: Prefix, location: L) -> bool {
+		self.get(key, prefix, location).is_some()
 	}
-	fn contains(&self, key: &K) -> bool {
-		PlainDB::contains(*self, key)
-	}
-}
-
-/// Trait modelling datastore keyed by a hash defined by the `Hasher`.
-pub trait HashDB<H: Hasher, T>: Send + Sync + AsHashDB<H, T> {
-	/// Look up a given hash into the bytes that hash to it, returning None if the
-	/// hash is not known.
-	fn get(&self, key: &H::Out, prefix: Prefix) -> Option<T>;
-
-	/// Check for the existence of a hash-key.
-	fn contains(&self, key: &H::Out, prefix: Prefix) -> bool;
-
-	/// Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions
-	/// are counted and the equivalent number of `remove()`s must be performed before the data
-	/// is considered dead.
-	fn insert(&mut self, prefix: Prefix, value: &[u8]) -> H::Out;
-
-	/// Like `insert()`, except you provide the key and the data is all moved.
-	fn emplace(&mut self, key: H::Out, prefix: Prefix, value: T);
-
-	/// Remove a datum previously inserted. Insertions can be "owed" such that the same number of
-	/// `insert()`s may happen without the data being eventually being inserted into the DB.
-	/// It can be "owed" more than once.
-	fn remove(&mut self, key: &H::Out, prefix: Prefix);
-}
 
-/// Trait for immutable reference of HashDB.
-pub trait HashDBRef<H: Hasher, T> {
-	/// Look up a given hash into the bytes that hash to it, returning None if the
-	/// hash is not known.
-	fn get(&self, key: &H::Out, prefix: Prefix) -> Option<T>;
-
-	/// Check for the existance of a hash-key.
-	fn contains(&self, key: &H::Out, prefix: Prefix) -> bool;
-}
-
-impl<'a, H: Hasher, T> HashDBRef<H, T> for &'a dyn HashDB<H, T> {
-	fn get(&self, key: &H::Out, prefix: Prefix) -> Option<T> {
-		HashDB::get(*self, key, prefix)
-	}
-	fn contains(&self, key: &H::Out, prefix: Prefix) -> bool {
-		HashDB::contains(*self, key, prefix)
-	}
-}
-
-impl<'a, H: Hasher, T> HashDBRef<H, T> for &'a mut dyn HashDB<H, T> {
-	fn get(&self, key: &H::Out, prefix: Prefix) -> Option<T> {
-		HashDB::get(*self, key, prefix)
-	}
-	fn contains(&self, key: &H::Out, prefix: Prefix) -> bool {
-		HashDB::contains(*self, key, prefix)
-	}
-}
-
-/// Upcast trait for HashDB.
-pub trait AsHashDB<H: Hasher, T> {
-	/// Perform upcast to HashDB for anything that derives from HashDB.
-	fn as_hash_db(&self) -> &dyn HashDB<H, T>;
-	/// Perform mutable upcast to HashDB for anything that derives from HashDB.
-	fn as_hash_db_mut<'a>(&'a mut self) -> &'a mut (dyn HashDB<H, T> + 'a);
-}
-
-/// Upcast trait for PlainDB.
-pub trait AsPlainDB<K, V> {
-	/// Perform upcast to PlainDB for anything that derives from PlainDB.
-	fn as_plain_db(&self) -> &dyn PlainDB<K, V>;
-	/// Perform mutable upcast to PlainDB for anything that derives from PlainDB.
-	fn as_plain_db_mut<'a>(&'a mut self) -> &'a mut (dyn PlainDB<K, V> + 'a);
-}
-
-// NOTE: There used to be a `impl<T> AsHashDB for T` but that does not work with generics.
-// See https://stackoverflow.com/questions/48432842/
-// implementing-a-trait-for-reference-and-non-reference-types-causes-conflicting-im
-// This means we need concrete impls of AsHashDB in several places, which somewhat defeats
-// the point of the trait.
-impl<'a, H: Hasher, T> AsHashDB<H, T> for &'a mut dyn HashDB<H, T> {
-	fn as_hash_db(&self) -> &dyn HashDB<H, T> {
-		&**self
-	}
-	fn as_hash_db_mut<'b>(&'b mut self) -> &'b mut (dyn HashDB<H, T> + 'b) {
-		&mut **self
-	}
-}
-
-#[cfg(feature = "std")]
-impl<'a, K, V> AsPlainDB<K, V> for &'a mut dyn PlainDB<K, V> {
-	fn as_plain_db(&self) -> &dyn PlainDB<K, V> {
-		&**self
-	}
-	fn as_plain_db_mut<'b>(&'b mut self) -> &'b mut (dyn PlainDB<K, V> + 'b) {
-		&mut **self
+	/// Compute value hash.
+	fn hash(&self, value: &[u8]) -> H::Out {
+		H::hash(value)
 	}
 }

memory-db/benches/bench.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use hash_db::{HashDB, Hasher, EMPTY_PREFIX};
+use hash_db::{Hasher, EMPTY_PREFIX};
 use keccak_hasher::KeccakHasher;
 use memory_db::{HashKey, MemoryDB};