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Refactor CachedTreeHash into owned bytes

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Instead of slices
This commit is contained in:
Paul Hauner 2019-03-28 09:33:44 +11:00
parent acb1dd47cd
commit b05787207f
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GPG Key ID: D362883A9218FCC6
1 changed files with 77 additions and 73 deletions
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150
eth2/utils/ssz/src/cached_tree_hash.rs
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@ -6,43 +6,29 @@ const BYTES_PER_CHUNK: usize = 32;
const HASHSIZE: usize = 32;
const MERKLE_HASH_CHUNCK: usize = 2 * BYTES_PER_CHUNK;
pub struct TreeHashCache<'a> {
chunk_offset: usize,
cache: &'a mut [u8],
chunk_modified: &'a mut [bool],
hash_count: &'a mut usize,
pub struct TreeHashCache {
cache: Vec<u8>,
chunk_modified: Vec<bool>,
}
impl<'a> TreeHashCache<'a> {
pub fn build_changes_vec(bytes: &[u8]) -> Vec<bool> {
vec![false; bytes.len() / BYTES_PER_CHUNK]
impl Into<Vec<u8>> for TreeHashCache {
fn into(self) -> Vec<u8> {
self.cache
}
}
pub fn from_mut_slice(
bytes: &'a mut [u8],
changes: &'a mut [bool],
hash_count: &'a mut usize,
) -> Option<Self> {
impl TreeHashCache {
pub fn from_bytes(bytes: Vec<u8>) -> Option<Self> {
if bytes.len() % BYTES_PER_CHUNK > 0 {
return None;
}
Some(Self {
chunk_offset: 0,
chunk_modified: vec![false; bytes.len() / BYTES_PER_CHUNK],
cache: bytes,
chunk_modified: changes,
hash_count,
})
}
pub fn increment(&mut self) {
self.chunk_offset += 1
}
pub fn modify_current_chunk(&mut self, to: &[u8]) -> Option<()> {
self.modify_chunk(self.chunk_offset, to)
}
pub fn modify_chunk(&mut self, chunk: usize, to: &[u8]) -> Option<()> {
let start = chunk * BYTES_PER_CHUNK;
let end = start + BYTES_PER_CHUNK;
@ -72,28 +58,6 @@ impl<'a> TreeHashCache<'a> {
Some(hash(&self.cache.get(start..end)?))
}
pub fn just_the_leaves(&mut self, leaves: usize) -> Option<TreeHashCache> {
let nodes = num_nodes(leaves);
let internal = nodes - leaves;
let leaves_start = (self.chunk_offset + internal) * BYTES_PER_CHUNK;
let leaves_end = leaves_start + leaves * BYTES_PER_CHUNK;
let modified_start = self.chunk_offset + internal;
let modified_end = modified_start + leaves;
Some(TreeHashCache {
chunk_offset: 0,
cache: self.cache.get_mut(leaves_start..leaves_end)?,
chunk_modified: self.chunk_modified.get_mut(modified_start..modified_end)?,
hash_count: self.hash_count,
})
}
pub fn into_slice(self) -> &'a [u8] {
self.cache
}
}
fn children(parent: usize) -> (usize, usize) {
@ -107,7 +71,16 @@ fn num_nodes(num_leaves: usize) -> usize {
pub trait CachedTreeHash {
fn build_cache_bytes(&self) -> Vec<u8>;
fn cached_hash_tree_root(&self, other: &Self, cache: &mut TreeHashCache) -> Option<()>;
fn num_bytes(&self) -> usize;
fn max_num_leaves(&self) -> usize;
fn cached_hash_tree_root(
&self,
other: &Self,
cache: &mut TreeHashCache,
chunk: usize,
) -> Option<usize>;
}
impl CachedTreeHash for u64 {
@ -115,15 +88,25 @@ impl CachedTreeHash for u64 {
merkleize(&int_to_bytes32(*self))
}
fn cached_hash_tree_root(&self, other: &Self, cache: &mut TreeHashCache) -> Option<()> {
fn num_bytes(&self) -> usize {
8
}
fn max_num_leaves(&self) -> usize {
1
}
fn cached_hash_tree_root(
&self,
other: &Self,
cache: &mut TreeHashCache,
chunk: usize,
) -> Option<usize> {
if self != other {
*cache.hash_count += 1;
cache.modify_current_chunk(&merkleize(&int_to_bytes32(*self)))?;
cache.modify_chunk(chunk, &merkleize(&int_to_bytes32(*self)))?;
}
cache.increment();
Some(())
Some(chunk + 1)
}
}
@ -147,28 +130,52 @@ impl CachedTreeHash for Inner {
merkleize(&leaves)
}
fn cached_hash_tree_root(&self, other: &Self, cache: &mut TreeHashCache) -> Option<()> {
let num_leaves = 4;
fn max_num_leaves(&self) -> usize {
let mut leaves = 0;
leaves += self.a.max_num_leaves();
leaves += self.b.max_num_leaves();
leaves += self.c.max_num_leaves();
leaves += self.d.max_num_leaves();
leaves
}
fn num_bytes(&self) -> usize {
let mut bytes = 0;
bytes += self.a.num_bytes();
bytes += self.b.num_bytes();
bytes += self.c.num_bytes();
bytes += self.d.num_bytes();
bytes
}
fn cached_hash_tree_root(
&self,
other: &Self,
cache: &mut TreeHashCache,
chunk: usize,
) -> Option<usize> {
let num_leaves = self.max_num_leaves();
let num_nodes = num_nodes(num_leaves);
let num_internal_nodes = num_nodes - num_leaves;
// Skip past the internal nodes and update any changed leaf nodes.
{
let mut leaf_cache = cache.just_the_leaves(num_leaves)?;
self.a.cached_hash_tree_root(&other.a, &mut leaf_cache)?;
self.b.cached_hash_tree_root(&other.b, &mut leaf_cache)?;
self.c.cached_hash_tree_root(&other.c, &mut leaf_cache)?;
self.d.cached_hash_tree_root(&other.d, &mut leaf_cache)?;
let chunk = chunk + num_internal_nodes;
let chunk = self.a.cached_hash_tree_root(&other.a, cache, chunk)?;
let chunk = self.b.cached_hash_tree_root(&other.b, cache, chunk)?;
let chunk = self.c.cached_hash_tree_root(&other.c, cache, chunk)?;
let _chunk = self.d.cached_hash_tree_root(&other.d, cache, chunk)?;
}
let nodes = num_nodes(num_leaves);
let internal_chunks = nodes - num_leaves;
for chunk in (0..internal_chunks).into_iter().rev() {
// Iterate backwards through the internal nodes, rehashing any node where it's children
// have changed.
for chunk in (0..num_internal_nodes).into_iter().rev() {
if cache.children_modified(chunk)? {
*cache.hash_count += 1;
cache.modify_chunk(chunk, &cache.hash_children(chunk)?)?;
}
}
Some(())
Some(chunk + num_nodes)
}
}
@ -243,18 +250,15 @@ mod tests {
_ => panic!("bad index"),
};
let mut changes = TreeHashCache::build_changes_vec(&cache);
let mut hash_count = 0;
let mut cache_struct =
TreeHashCache::from_mut_slice(&mut cache, &mut changes, &mut hash_count).unwrap();
let mut cache_struct = TreeHashCache::from_bytes(cache.clone()).unwrap();
changed_inner
.cached_hash_tree_root(&inner, &mut cache_struct)
.cached_hash_tree_root(&inner, &mut cache_struct, 0)
.unwrap();
assert_eq!(*cache_struct.hash_count, 3);
// assert_eq!(*cache_struct.hash_count, 3);
let new_cache = cache_struct.into_slice();
let new_cache: Vec<u8> = cache_struct.into();
let data1 = int_to_bytes32(1);
let data2 = int_to_bytes32(2);