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Implement CachedTreeHash for TreeHashVector

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This commit is contained in:
Paul Hauner 2019-04-26 11:15:17 +10:00
parent f1d8224d89
commit 15f81c0907
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7 changed files with 215 additions and 149 deletions
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1
eth2/types/Cargo.toml
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@ -7,6 +7,7 @@ edition = "2018"
[dependencies]
bls = { path = "../utils/bls" }
boolean-bitfield = { path = "../utils/boolean-bitfield" }
cached_tree_hash = { path = "../utils/cached_tree_hash" }
dirs = "1.0"
derivative = "1.0"
ethereum-types = "0.5"

38
eth2/types/src/tree_hash_vector.rs
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@ -1,4 +1,5 @@
use crate::test_utils::{RngCore, TestRandom};
use cached_tree_hash::CachedTreeHash;
use serde_derive::{Deserialize, Serialize};
use ssz::{Decodable, DecodeError, Encodable, SszStream};
use std::ops::{Deref, DerefMut};
@ -54,6 +55,43 @@ where
}
}
impl<T> CachedTreeHash<TreeHashVector<T>> for TreeHashVector<T>
where
T: CachedTreeHash<T> + TreeHash,
{
fn new_tree_hash_cache(
&self,
depth: usize,
) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
let (cache, _overlay) = cached_tree_hash::impls::vec::new_tree_hash_cache(self, depth)?;
Ok(cache)
}
fn num_tree_hash_cache_chunks(&self) -> usize {
cached_tree_hash::BTreeOverlay::new(self, 0, 0)
.and_then(|o| Ok(o.num_chunks()))
.unwrap_or_else(|_| 1)
}
fn tree_hash_cache_overlay(
&self,
chunk_offset: usize,
depth: usize,
) -> Result<cached_tree_hash::BTreeOverlay, cached_tree_hash::Error> {
cached_tree_hash::impls::vec::produce_overlay(self, chunk_offset, depth)
}
fn update_tree_hash_cache(
&self,
cache: &mut cached_tree_hash::TreeHashCache,
) -> Result<(), cached_tree_hash::Error> {
cached_tree_hash::impls::vec::update_tree_hash_cache(self, cache)?;
Ok(())
}
}
impl<T> Encodable for TreeHashVector<T>
where
T: Encodable,

2
eth2/utils/cached_tree_hash/src/impls.rs
View File

@ -1,7 +1,7 @@
use super::*;
use crate::merkleize::merkleize;
mod vec;
pub mod vec;
impl CachedTreeHash<u64> for u64 {
fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {

316
eth2/utils/cached_tree_hash/src/impls/vec.rs
View File

@ -6,23 +6,7 @@ where
T: CachedTreeHash<T> + TreeHash,
{
fn new_tree_hash_cache(&self, depth: usize) -> Result<TreeHashCache, Error> {
let overlay = self.tree_hash_cache_overlay(0, depth)?;
let mut cache = match T::tree_hash_type() {
TreeHashType::Basic => TreeHashCache::from_bytes(
merkleize(get_packed_leaves(self)?),
false,
Some(overlay.clone()),
),
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
let subtrees = self
.iter()
.map(|item| TreeHashCache::new(item, depth + 1))
.collect::<Result<Vec<TreeHashCache>, _>>()?;
TreeHashCache::from_leaves_and_subtrees(self, subtrees, depth)
}
}?;
let (mut cache, overlay) = new_tree_hash_cache(self, depth)?;
cache.add_length_nodes(overlay.chunk_range(), self.len())?;
@ -33,7 +17,7 @@ where
BTreeOverlay::new(self, 0, 0)
.and_then(|o| Ok(o.num_chunks()))
.unwrap_or_else(|_| 1)
+ 2
+ 2 // Add two extra nodes to cater for the length.
}
fn tree_hash_cache_overlay(
@ -41,139 +25,15 @@ where
chunk_offset: usize,
depth: usize,
) -> Result<BTreeOverlay, Error> {
let lengths = match T::tree_hash_type() {
TreeHashType::Basic => {
// Ceil division.
let num_leaves = (self.len() + T::tree_hash_packing_factor() - 1)
/ T::tree_hash_packing_factor();
// Disallow zero-length as an empty list still has one all-padding node.
vec![1; std::cmp::max(1, num_leaves)]
}
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
let mut lengths = vec![];
for item in self {
lengths.push(item.num_tree_hash_cache_chunks())
}
// Disallow zero-length as an empty list still has one all-padding node.
if lengths.is_empty() {
lengths.push(1);
}
lengths
}
};
BTreeOverlay::from_lengths(chunk_offset, self.len(), depth, lengths)
produce_overlay(self, chunk_offset, depth)
}
fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
// Skip the length-mixed-in root node.
cache.chunk_index += 1;
let old_overlay = cache.get_overlay(cache.overlay_index, cache.chunk_index)?;
let new_overlay = BTreeOverlay::new(self, cache.chunk_index, old_overlay.depth)?;
cache.replace_overlay(cache.overlay_index, cache.chunk_index, new_overlay.clone())?;
cache.overlay_index += 1;
match T::tree_hash_type() {
TreeHashType::Basic => {
let mut buf = vec![0; HASHSIZE];
let item_bytes = HASHSIZE / T::tree_hash_packing_factor();
// Iterate through each of the leaf nodes.
for i in 0..new_overlay.num_leaf_nodes() {
// Iterate through the number of items that may be packing into the leaf node.
for j in 0..T::tree_hash_packing_factor() {
// Create a mut slice that can be filled with either a serialized item or
// padding.
let buf_slice = &mut buf[j * item_bytes..(j + 1) * item_bytes];
// Attempt to get the item for this portion of the chunk. If it exists,
// update `buf` with it's serialized bytes. If it doesn't exist, update
// `buf` with padding.
match self.get(i * T::tree_hash_packing_factor() + j) {
Some(item) => {
buf_slice.copy_from_slice(&item.tree_hash_packed_encoding());
}
None => buf_slice.copy_from_slice(&vec![0; item_bytes]),
}
}
// Update the chunk if the generated `buf` is not the same as the cache.
let chunk = new_overlay.first_leaf_node() + i;
cache.maybe_update_chunk(chunk, &buf)?;
}
}
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
for i in 0..new_overlay.num_leaf_nodes() {
// Adjust `i` so it is a leaf node for each of the overlays.
let old_i = i + old_overlay.num_internal_nodes();
let new_i = i + new_overlay.num_internal_nodes();
match (
old_overlay.get_leaf_node(old_i)?,
new_overlay.get_leaf_node(new_i)?,
) {
// The item existed in the previous list and exists in the current list.
(Some(_old), Some(new)) => {
cache.chunk_index = new.start;
self[i].update_tree_hash_cache(cache)?;
}
// The item did not exist in the previous list but does exist in this list.
//
// Viz., the list has been lengthened.
(None, Some(new)) => {
let (bytes, mut bools, overlays) =
TreeHashCache::new(&self[i], new_overlay.depth + 1)?
.into_components();
// Record the number of overlays, this will be used later in the fn.
let num_overlays = overlays.len();
// Flag the root node of the new tree as dirty.
bools[0] = true;
cache.splice(new.start..new.start + 1, bytes, bools);
cache
.overlays
.splice(cache.overlay_index..cache.overlay_index, overlays);
cache.overlay_index += num_overlays;
}
// The item existed in the previous list but does not exist in this list.
//
// Viz., the list has been shortened.
(Some(old), None) => {
if new_overlay.num_items == 0 {
// In this case, the list has been made empty and we should make
// this node padding.
cache.maybe_update_chunk(new_overlay.root(), &[0; HASHSIZE])?;
} else {
// In this case, there are some items in the new list and we should
// splice out the entire tree of the removed node, replacing it
// with a single padding node.
cache.splice(old, vec![0; HASHSIZE], vec![true]);
}
}
// The item didn't exist in the old list and doesn't exist in the new list,
// nothing to do.
(None, None) => {}
}
}
// Clean out any excess overlays that may or may not be remaining if the list was
// shortened.
cache.remove_proceeding_child_overlays(cache.overlay_index, new_overlay.depth);
}
}
cache.update_internal_nodes(&new_overlay)?;
// Update the cache, returning the new overlay.
let new_overlay = update_tree_hash_cache(self, cache)?;
// Mix in length
cache.mix_in_length(new_overlay.chunk_range(), self.len())?;
@ -185,6 +45,172 @@ where
}
}
pub fn new_tree_hash_cache<T: CachedTreeHash<T>>(
vec: &Vec<T>,
depth: usize,
) -> Result<(TreeHashCache, BTreeOverlay), Error> {
let overlay = vec.tree_hash_cache_overlay(0, depth)?;
let cache = match T::tree_hash_type() {
TreeHashType::Basic => TreeHashCache::from_bytes(
merkleize(get_packed_leaves(vec)?),
false,
Some(overlay.clone()),
),
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
let subtrees = vec
.iter()
.map(|item| TreeHashCache::new(item, depth + 1))
.collect::<Result<Vec<TreeHashCache>, _>>()?;
TreeHashCache::from_leaves_and_subtrees(vec, subtrees, depth)
}
}?;
Ok((cache, overlay))
}
pub fn produce_overlay<T: CachedTreeHash<T>>(
vec: &Vec<T>,
chunk_offset: usize,
depth: usize,
) -> Result<BTreeOverlay, Error> {
let lengths = match T::tree_hash_type() {
TreeHashType::Basic => {
// Ceil division.
let num_leaves =
(vec.len() + T::tree_hash_packing_factor() - 1) / T::tree_hash_packing_factor();
// Disallow zero-length as an empty list still has one all-padding node.
vec![1; std::cmp::max(1, num_leaves)]
}
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
let mut lengths = vec![];
for item in vec {
lengths.push(item.num_tree_hash_cache_chunks())
}
// Disallow zero-length as an empty list still has one all-padding node.
if lengths.is_empty() {
lengths.push(1);
}
lengths
}
};
BTreeOverlay::from_lengths(chunk_offset, vec.len(), depth, lengths)
}
pub fn update_tree_hash_cache<T: CachedTreeHash<T>>(
vec: &Vec<T>,
cache: &mut TreeHashCache,
) -> Result<BTreeOverlay, Error> {
let old_overlay = cache.get_overlay(cache.overlay_index, cache.chunk_index)?;
let new_overlay = BTreeOverlay::new(vec, cache.chunk_index, old_overlay.depth)?;
cache.replace_overlay(cache.overlay_index, cache.chunk_index, new_overlay.clone())?;
cache.overlay_index += 1;
match T::tree_hash_type() {
TreeHashType::Basic => {
let mut buf = vec![0; HASHSIZE];
let item_bytes = HASHSIZE / T::tree_hash_packing_factor();
// Iterate through each of the leaf nodes.
for i in 0..new_overlay.num_leaf_nodes() {
// Iterate through the number of items that may be packing into the leaf node.
for j in 0..T::tree_hash_packing_factor() {
// Create a mut slice that can be filled with either a serialized item or
// padding.
let buf_slice = &mut buf[j * item_bytes..(j + 1) * item_bytes];
// Attempt to get the item for this portion of the chunk. If it exists,
// update `buf` with it's serialized bytes. If it doesn't exist, update
// `buf` with padding.
match vec.get(i * T::tree_hash_packing_factor() + j) {
Some(item) => {
buf_slice.copy_from_slice(&item.tree_hash_packed_encoding());
}
None => buf_slice.copy_from_slice(&vec![0; item_bytes]),
}
}
// Update the chunk if the generated `buf` is not the same as the cache.
let chunk = new_overlay.first_leaf_node() + i;
cache.maybe_update_chunk(chunk, &buf)?;
}
}
TreeHashType::Container | TreeHashType::List | TreeHashType::Vector => {
for i in 0..new_overlay.num_leaf_nodes() {
// Adjust `i` so it is a leaf node for each of the overlays.
let old_i = i + old_overlay.num_internal_nodes();
let new_i = i + new_overlay.num_internal_nodes();
match (
old_overlay.get_leaf_node(old_i)?,
new_overlay.get_leaf_node(new_i)?,
) {
// The item existed in the previous list and exists in the current list.
(Some(_old), Some(new)) => {
cache.chunk_index = new.start;
vec[i].update_tree_hash_cache(cache)?;
}
// The item did not exist in the previous list but does exist in this list.
//
// Viz., the list has been lengthened.
(None, Some(new)) => {
let (bytes, mut bools, overlays) =
TreeHashCache::new(&vec[i], new_overlay.depth + 1)?.into_components();
// Record the number of overlays, this will be used later in the fn.
let num_overlays = overlays.len();
// Flag the root node of the new tree as dirty.
bools[0] = true;
cache.splice(new.start..new.start + 1, bytes, bools);
cache
.overlays
.splice(cache.overlay_index..cache.overlay_index, overlays);
cache.overlay_index += num_overlays;
}
// The item existed in the previous list but does not exist in this list.
//
// Viz., the list has been shortened.
(Some(old), None) => {
if new_overlay.num_items == 0 {
// In this case, the list has been made empty and we should make
// this node padding.
cache.maybe_update_chunk(new_overlay.root(), &[0; HASHSIZE])?;
} else {
// In this case, there are some items in the new list and we should
// splice out the entire tree of the removed node, replacing it
// with a single padding node.
cache.splice(old, vec![0; HASHSIZE], vec![true]);
}
}
// The item didn't exist in the old list and doesn't exist in the new list,
// nothing to do.
(None, None) => {}
}
}
// Clean out any excess overlays that may or may not be remaining if the list was
// shortened.
cache.remove_proceeding_child_overlays(cache.overlay_index, new_overlay.depth);
}
}
cache.update_internal_nodes(&new_overlay)?;
Ok(new_overlay)
}
fn get_packed_leaves<T>(vec: &Vec<T>) -> Result<Vec<u8>, Error>
where
T: CachedTreeHash<T>,

2
eth2/utils/cached_tree_hash/src/lib.rs
View File

@ -4,7 +4,7 @@ use tree_hash::{TreeHash, TreeHashType, BYTES_PER_CHUNK, HASHSIZE};
mod btree_overlay;
mod errors;
mod impls;
pub mod impls;
pub mod merkleize;
mod resize;
mod tree_hash_cache;

4
eth2/utils/tree_hash/src/impls.rs
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@ -56,11 +56,11 @@ impl TreeHash for [u8; 4] {
}
fn tree_hash_packed_encoding(&self) -> Vec<u8> {
panic!("bytesN should never be packed.")
unreachable!("bytesN should never be packed.")
}
fn tree_hash_packing_factor() -> usize {
panic!("bytesN should never be packed.")
unreachable!("bytesN should never be packed.")
}
fn tree_hash_root(&self) -> Vec<u8> {

1
eth2/utils/tree_hash/src/lib.rs
View File

@ -49,6 +49,7 @@ macro_rules! tree_hash_ssz_encoding_as_vector {
}
};
}
#[macro_export]
macro_rules! tree_hash_ssz_encoding_as_list {
($type: ident) => {