Add uncached tree hashing

eth2/utils/tree_hash/src/cached_tree_hash.rs

@@ -1,4 +1,129 @@
 use super::*;
+use hashing::hash;
+use int_to_bytes::int_to_bytes32;
+use std::ops::Range;
+
+pub mod btree_overlay;
+pub mod impls;
+pub mod resize;
+
+pub use btree_overlay::BTreeOverlay;
+
+#[derive(Debug, PartialEq, Clone)]
+pub enum Error {
+    ShouldNotProduceBTreeOverlay,
+    NoFirstNode,
+    NoBytesForRoot,
+    UnableToObtainSlices,
+    UnableToGrowMerkleTree,
+    UnableToShrinkMerkleTree,
+    ShouldNeverBePacked(ItemType),
+    BytesAreNotEvenChunks(usize),
+    NoModifiedFieldForChunk(usize),
+    NoBytesForChunk(usize),
+}
+
+pub trait CachedTreeHash<T>: CachedTreeHashSubTree<T> + Sized {
+    fn update_internal_tree_hash_cache(self, old: T) -> Result<(Self, Self), Error>;
+
+    fn cached_tree_hash_root(&self) -> Option<Vec<u8>>;
+
+    fn clone_without_tree_hash_cache(&self) -> Self;
+}
+
+pub trait CachedTreeHashSubTree<Item> {
+    fn item_type() -> ItemType;
+
+    fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error>;
+
+    fn packed_encoding(&self) -> Result<Vec<u8>, Error>;
+
+    fn packing_factor() -> usize;
+
+    fn new_cache(&self) -> Result<TreeHashCache, Error>;
+
+    fn update_cache(
+        &self,
+        other: &Item,
+        cache: &mut TreeHashCache,
+        chunk: usize,
+    ) -> Result<usize, Error>;
+}
+
+fn children(parent: usize) -> (usize, usize) {
+    ((2 * parent + 1), (2 * parent + 2))
+}
+
+fn node_range_to_byte_range(node_range: &Range<usize>) -> Range<usize> {
+    node_range.start * HASHSIZE..node_range.end * HASHSIZE
+}
+
+/// Split `values` into a power-of-two, identical-length chunks (padding with `0`) and merkleize
+/// them, returning the entire merkle tree.
+///
+/// The root hash is `merkleize(values)[0..BYTES_PER_CHUNK]`.
+pub fn merkleize(values: Vec<u8>) -> Vec<u8> {
+    let values = sanitise_bytes(values);
+
+    let leaves = values.len() / HASHSIZE;
+
+    if leaves == 0 {
+        panic!("No full leaves");
+    }
+
+    if !leaves.is_power_of_two() {
+        panic!("leaves is not power of two");
+    }
+
+    let mut o: Vec<u8> = vec![0; (num_nodes(leaves) - leaves) * HASHSIZE];
+    o.append(&mut values.to_vec());
+
+    let mut i = o.len();
+    let mut j = o.len() - values.len();
+
+    while i >= MERKLE_HASH_CHUNCK {
+        i -= MERKLE_HASH_CHUNCK;
+        let hash = hash(&o[i..i + MERKLE_HASH_CHUNCK]);
+
+        j -= HASHSIZE;
+        o[j..j + HASHSIZE].copy_from_slice(&hash);
+    }
+
+    o
+}
+
+pub fn sanitise_bytes(mut bytes: Vec<u8>) -> Vec<u8> {
+    let present_leaves = num_unsanitized_leaves(bytes.len());
+    let required_leaves = present_leaves.next_power_of_two();
+
+    if (present_leaves != required_leaves) | last_leaf_needs_padding(bytes.len()) {
+        bytes.resize(num_bytes(required_leaves), 0);
+    }
+
+    bytes
+}
+
+fn pad_for_leaf_count(num_leaves: usize, bytes: &mut Vec<u8>) {
+    let required_leaves = num_leaves.next_power_of_two();
+
+    bytes.resize(
+        bytes.len() + (required_leaves - num_leaves) * BYTES_PER_CHUNK,
+        0,
+    );
+}
+
+fn last_leaf_needs_padding(num_bytes: usize) -> bool {
+    num_bytes % HASHSIZE != 0
+}
+
+/// Rounds up
+fn num_unsanitized_leaves(num_bytes: usize) -> usize {
+    (num_bytes + HASHSIZE - 1) / HASHSIZE
+}
+
+fn num_bytes(num_leaves: usize) -> usize {
+    num_leaves * HASHSIZE
+}
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct TreeHashCache {

eth2/utils/tree_hash/src/lib.rs

@@ -1,33 +1,10 @@
-use hashing::hash;
-use int_to_bytes::int_to_bytes32;
-use std::ops::Range;
-
-mod btree_overlay;
-mod cached_tree_hash;
-mod impls;
-mod resize;
-
-pub use btree_overlay::BTreeOverlay;
-pub use cached_tree_hash::TreeHashCache;
+pub mod cached_tree_hash;
+pub mod standard_tree_hash;
 
 pub const BYTES_PER_CHUNK: usize = 32;
 pub const HASHSIZE: usize = 32;
 pub const MERKLE_HASH_CHUNCK: usize = 2 * BYTES_PER_CHUNK;
 
-#[derive(Debug, PartialEq, Clone)]
-pub enum Error {
-    ShouldNotProduceBTreeOverlay,
-    NoFirstNode,
-    NoBytesForRoot,
-    UnableToObtainSlices,
-    UnableToGrowMerkleTree,
-    UnableToShrinkMerkleTree,
-    ShouldNeverBePacked(ItemType),
-    BytesAreNotEvenChunks(usize),
-    NoModifiedFieldForChunk(usize),
-    NoBytesForChunk(usize),
-}
-
 #[derive(Debug, PartialEq, Clone)]
 pub enum ItemType {
     Basic,
@@ -35,114 +12,11 @@ pub enum ItemType {
     Composite,
 }
 
-pub trait CachedTreeHash<T>: CachedTreeHashSubTree<T> + Sized {
-    fn update_internal_tree_hash_cache(self, old: T) -> Result<(Self, Self), Error>;
-
-    fn cached_tree_hash_root(&self) -> Option<Vec<u8>>;
-
-    fn clone_without_tree_hash_cache(&self) -> Self;
-}
-
-pub trait CachedTreeHashSubTree<Item> {
-    fn item_type() -> ItemType;
-
-    fn btree_overlay(&self, chunk_offset: usize) -> Result<BTreeOverlay, Error>;
-
-    fn packed_encoding(&self) -> Result<Vec<u8>, Error>;
-
-    fn packing_factor() -> usize;
-
-    fn new_cache(&self) -> Result<TreeHashCache, Error>;
-
-    fn update_cache(
-        &self,
-        other: &Item,
-        cache: &mut TreeHashCache,
-        chunk: usize,
-    ) -> Result<usize, Error>;
-}
-
-fn children(parent: usize) -> (usize, usize) {
-    ((2 * parent + 1), (2 * parent + 2))
-}
-
-fn num_nodes(num_leaves: usize) -> usize {
-    2 * num_leaves - 1
-}
-
-fn node_range_to_byte_range(node_range: &Range<usize>) -> Range<usize> {
-    node_range.start * HASHSIZE..node_range.end * HASHSIZE
-}
-
-/// Split `values` into a power-of-two, identical-length chunks (padding with `0`) and merkleize
-/// them, returning the entire merkle tree.
-///
-/// The root hash is `merkleize(values)[0..BYTES_PER_CHUNK]`.
-pub fn merkleize(values: Vec<u8>) -> Vec<u8> {
-    let values = sanitise_bytes(values);
-
-    let leaves = values.len() / HASHSIZE;
-
-    if leaves == 0 {
-        panic!("No full leaves");
-    }
-
-    if !leaves.is_power_of_two() {
-        panic!("leaves is not power of two");
-    }
-
-    let mut o: Vec<u8> = vec![0; (num_nodes(leaves) - leaves) * HASHSIZE];
-    o.append(&mut values.to_vec());
-
-    let mut i = o.len();
-    let mut j = o.len() - values.len();
-
-    while i >= MERKLE_HASH_CHUNCK {
-        i -= MERKLE_HASH_CHUNCK;
-        let hash = hash(&o[i..i + MERKLE_HASH_CHUNCK]);
-
-        j -= HASHSIZE;
-        o[j..j + HASHSIZE].copy_from_slice(&hash);
-    }
-
-    o
-}
-
-pub fn sanitise_bytes(mut bytes: Vec<u8>) -> Vec<u8> {
-    let present_leaves = num_unsanitized_leaves(bytes.len());
-    let required_leaves = present_leaves.next_power_of_two();
-
-    if (present_leaves != required_leaves) | last_leaf_needs_padding(bytes.len()) {
-        bytes.resize(num_bytes(required_leaves), 0);
-    }
-
-    bytes
-}
-
-fn pad_for_leaf_count(num_leaves: usize, bytes: &mut Vec<u8>) {
-    let required_leaves = num_leaves.next_power_of_two();
-
-    bytes.resize(
-        bytes.len() + (required_leaves - num_leaves) * BYTES_PER_CHUNK,
-        0,
-    );
-}
-
-fn last_leaf_needs_padding(num_bytes: usize) -> bool {
-    num_bytes % HASHSIZE != 0
-}
-
-/// Rounds up
-fn num_unsanitized_leaves(num_bytes: usize) -> usize {
-    (num_bytes + HASHSIZE - 1) / HASHSIZE
-}
-
-/// Rounds up
 fn num_sanitized_leaves(num_bytes: usize) -> usize {
     let leaves = (num_bytes + HASHSIZE - 1) / HASHSIZE;
     leaves.next_power_of_two()
 }
 
-fn num_bytes(num_leaves: usize) -> usize {
-    num_leaves * HASHSIZE
+fn num_nodes(num_leaves: usize) -> usize {
+    2 * num_leaves - 1
 }

eth2/utils/tree_hash/src/standard_tree_hash.rs

@@ -0,0 +1,114 @@
+use super::*;
+use hashing::hash;
+use int_to_bytes::int_to_bytes32;
+use ssz::ssz_encode;
+
+pub trait TreeHash {
+    fn tree_hash_item_type() -> ItemType;
+
+    fn tree_hash_packed_encoding(&self) -> Vec<u8>;
+
+    fn hash_tree_root(&self) -> Vec<u8>;
+}
+
+impl TreeHash for u64 {
+    fn tree_hash_item_type() -> ItemType {
+        ItemType::Basic
+    }
+
+    fn tree_hash_packed_encoding(&self) -> Vec<u8> {
+        ssz_encode(self)
+    }
+
+    fn hash_tree_root(&self) -> Vec<u8> {
+        int_to_bytes32(*self)
+    }
+}
+
+impl<T> TreeHash for Vec<T>
+where
+    T: TreeHash,
+{
+    fn tree_hash_item_type() -> ItemType {
+        ItemType::List
+    }
+
+    fn tree_hash_packed_encoding(&self) -> Vec<u8> {
+        unreachable!("List should never be packed.")
+    }
+
+    fn hash_tree_root(&self) -> Vec<u8> {
+        let leaves = match T::tree_hash_item_type() {
+            ItemType::Basic => {
+                let mut leaves = vec![];
+
+                for item in self {
+                    leaves.append(&mut item.tree_hash_packed_encoding());
+                }
+
+                leaves
+            }
+            ItemType::Composite | ItemType::List => {
+                let mut leaves = Vec::with_capacity(self.len() * HASHSIZE);
+
+                for item in self {
+                    leaves.append(&mut item.hash_tree_root())
+                }
+
+                leaves
+            }
+        };
+
+        // Mix in the length
+        let mut root_and_len = Vec::with_capacity(HASHSIZE * 2);
+        root_and_len.append(&mut efficient_merkleize(&leaves)[0..32].to_vec());
+        root_and_len.append(&mut int_to_bytes32(self.len() as u64));
+
+        hash(&root_and_len)
+    }
+}
+
+pub fn efficient_merkleize(bytes: &[u8]) -> Vec<u8> {
+    let leaves = num_sanitized_leaves(bytes.len());
+    let nodes = num_nodes(leaves);
+    let internal_nodes = nodes - leaves;
+
+    let num_bytes = internal_nodes * HASHSIZE + bytes.len();
+
+    let mut o: Vec<u8> = vec![0; internal_nodes * HASHSIZE];
+    o.append(&mut bytes.to_vec());
+
+    assert_eq!(o.len(), num_bytes);
+
+    let empty_chunk_hash = hash(&[0; MERKLE_HASH_CHUNCK]);
+
+    let mut i = nodes * HASHSIZE;
+    let mut j = internal_nodes * HASHSIZE;
+
+    while i >= MERKLE_HASH_CHUNCK {
+        i -= MERKLE_HASH_CHUNCK;
+
+        j -= HASHSIZE;
+        let hash = match o.get(i..i + MERKLE_HASH_CHUNCK) {
+            // All bytes are available, hash as ususal.
+            Some(slice) => hash(slice),
+            // Unable to get all the bytes.
+            None => {
+                match o.get(i..) {
+                    // Able to get some of the bytes, pad them out.
+                    Some(slice) => {
+                        let mut bytes = slice.to_vec();
+                        bytes.resize(MERKLE_HASH_CHUNCK, 0);
+                        hash(&bytes)
+                    }
+                    // Unable to get any bytes, use the empty-chunk hash.
+                    None => empty_chunk_hash.clone(),
+                }
+            }
+        };
+
+        o[j..j + HASHSIZE].copy_from_slice(&hash);
+    }
+
+    o
+}

eth2/utils/tree_hash/tests/tests.rs

@@ -1,5 +1,7 @@
 use hashing::hash;
 use int_to_bytes::{int_to_bytes32, int_to_bytes8};
+use tree_hash::cached_tree_hash::*;
+use tree_hash::standard_tree_hash::*;
 use tree_hash::*;
 
 #[derive(Clone, Debug)]
@@ -131,6 +133,27 @@ pub struct Inner {
     pub d: u64,
 }
 
+impl TreeHash for Inner {
+    fn tree_hash_item_type() -> ItemType {
+        ItemType::Composite
+    }
+
+    fn tree_hash_packed_encoding(&self) -> Vec<u8> {
+        unreachable!("Struct should never be packed.")
+    }
+
+    fn hash_tree_root(&self) -> Vec<u8> {
+        let mut leaves = Vec::with_capacity(4 * HASHSIZE);
+
+        leaves.append(&mut self.a.hash_tree_root());
+        leaves.append(&mut self.b.hash_tree_root());
+        leaves.append(&mut self.c.hash_tree_root());
+        leaves.append(&mut self.d.hash_tree_root());
+
+        efficient_merkleize(&leaves)[0..32].to_vec()
+    }
+}
+
 impl CachedTreeHashSubTree<Inner> for Inner {
     fn item_type() -> ItemType {
         ItemType::Composite
@@ -458,6 +481,7 @@ fn test_u64_vec_modifications(original: Vec<u64>, modified: Vec<u64>) {
     mix_in_length(&mut expected[0..HASHSIZE], modified.len());
 
     assert_eq!(expected, modified_cache);
+    assert_eq!(&expected[0..32], &modified.hash_tree_root()[..]);
 }
 
 #[test]
@@ -580,6 +604,7 @@ fn test_inner_vec_modifications(original: Vec<Inner>, modified: Vec<Inner>, refe
 
     // Compare the cached tree to the reference tree.
     assert_trees_eq(&expected, &modified_cache);
+    assert_eq!(&expected[0..32], &modified.hash_tree_root()[..]);
 }
 
 #[test]