Fast and robust atproto CAR file processing in rust
custom mst node deserialize
try to put the data into a more walk-friendly shape
oops it made things slower
benches:
huge: +0.36% (within noise margin)
midsize: +3.3%
little: +3.7%
tiny: +4.6%
empty: +6.4%
authored by
phil
and committed by
tangled.org
cc77d06f
483f9d6c
+201
-86
+137
-12
src/mst.rs
+137
-12
src/mst.rs
···
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use cid::Cid;
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use serde::Deserialize;
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use crate::walk::Depth;
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/// The top-level data object in a repository's tree is a signed commit.
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#[derive(Debug, Deserialize)]
···
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pub prev: Option<Cid>,
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/// cryptographic signature of this commit, as raw bytes
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#[serde(with = "serde_bytes")]
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pub sig: Vec<u8>,
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pub sig: serde_bytes::ByteBuf,
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}
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use serde::{de, de::{Deserializer, Visitor, MapAccess, SeqAccess}};
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use std::fmt;
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pub(crate) enum NodeEntry {
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Value(Cid, Vec<u8>), // rkey
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Tree(Cid, u32), // depth
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}
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pub(crate) struct MstNode {
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pub left: Option<Cid>, // a tree but we don't know the depth
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pub entries: Vec<NodeEntry>,
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}
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pub(crate) struct Entries(pub(crate) Vec<NodeEntry>);
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impl<'de> Deserialize<'de> for Entries {
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where
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D: Deserializer<'de>,
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{
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struct EntriesVisitor;
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impl<'de> Visitor<'de> for EntriesVisitor {
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type Value = Entries;
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fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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formatter.write_str("seq MstEntries")
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}
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fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
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where
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S: SeqAccess<'de>,
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{
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let mut children: Vec<NodeEntry> = Vec::with_capacity(seq.size_hint().unwrap_or(5));
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let mut prefix: Vec<u8> = vec![];
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while let Some(entry) = seq.next_element::<Entry>()? {
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let mut rkey: Vec<u8> = vec![];
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let pre_checked = prefix
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.get(..entry.prefix_len)
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// .ok_or(MstError::EntryPrefixOutOfbounds)?;
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.ok_or_else(|| todo!()).unwrap();
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rkey.extend_from_slice(pre_checked);
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rkey.extend_from_slice(&entry.keysuffix);
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let depth = Depth::compute(&rkey);
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prefix = rkey.clone();
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children.push(NodeEntry::Value(entry.value, rkey));
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if let Some(ref tree) = entry.tree {
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children.push(NodeEntry::Tree(*tree, depth));
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}
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}
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Ok(Entries(children))
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}
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}
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deserializer.deserialize_seq(EntriesVisitor)
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}
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}
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impl<'de> Deserialize<'de> for MstNode {
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where
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D: Deserializer<'de>,
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{
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struct NodeVisitor;
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impl<'de> Visitor<'de> for NodeVisitor {
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type Value = MstNode;
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fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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formatter.write_str("struct MstNode")
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}
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fn visit_map<V>(self, mut map: V) -> Result<MstNode, V::Error>
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where
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V: MapAccess<'de>,
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{
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let mut found_left = false;
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let mut left = None;
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let mut found_entries = false;
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let mut entries = Vec::with_capacity(4); // "fanout of 4" so does this make sense????
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while let Some(key) = map.next_key()? {
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match key {
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"l" => {
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if found_left {
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return Err(de::Error::duplicate_field("l"));
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}
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found_left = true;
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left = map.next_value()?;
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}
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"e" => {
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if found_entries {
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return Err(de::Error::duplicate_field("e"));
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}
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found_entries = true;
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let mut child_entries: Entries = map.next_value()?;
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entries.append(&mut child_entries.0);
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},
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f => return Err(de::Error::unknown_field(f, NODE_FIELDS))
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}
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}
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if !found_left {
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return Err(de::Error::missing_field("l"));
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}
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if !found_entries {
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return Err(de::Error::missing_field("e"));
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}
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Ok(MstNode { left, entries })
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}
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}
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const NODE_FIELDS: &[&str] = &["l", "e"];
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deserializer.deserialize_struct("MstNode", NODE_FIELDS, NodeVisitor)
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}
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}
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impl MstNode {
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pub(crate) fn is_empty(&self) -> bool {
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self.left.is_none() && self.entries.is_empty()
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}
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}
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/// MST node data schema
···
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/// so if a block *could be* a node, any record converter must postpone
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/// processing. if it turns out it happens to be a very node-looking record,
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/// well, sorry, it just has to only be processed later when that's known.
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#[inline(always)]
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pub(crate) fn could_be(bytes: impl AsRef<[u8]>) -> bool {
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const NODE_FINGERPRINT: [u8; 3] = [
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0xA2, // map length 2 (for "l" and "e" keys)
···
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.unwrap_or(false)
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}
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/// Check if a node has any entries
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///
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/// An empty repository with no records is represented as a single MST node
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/// with an empty array of entries. This is the only situation in which a
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/// tree may contain an empty leaf node which does not either contain keys
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/// ("entries") or point to a sub-tree containing entries.
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pub(crate) fn is_empty(&self) -> bool {
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self.left.is_none() && self.entries.is_empty()
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}
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// /// Check if a node has any entries
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// ///
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// /// An empty repository with no records is represented as a single MST node
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// /// with an empty array of entries. This is the only situation in which a
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// /// tree may contain an empty leaf node which does not either contain keys
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// /// ("entries") or point to a sub-tree containing entries.
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// pub(crate) fn is_empty(&self) -> bool {
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// self.left.is_none() && self.entries.is_empty()
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// }
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}
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/// TreeEntry object
···
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#[serde(rename = "p")]
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pub prefix_len: usize,
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/// remainder of key for this TreeEntry, after "prefixlen" have been removed
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#[serde(rename = "k", with = "serde_bytes")]
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pub keysuffix: Vec<u8>, // can we String this here?
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#[serde(rename = "k")]
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pub keysuffix: serde_bytes::ByteBuf,
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/// link to the record data (CBOR) for this entry
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#[serde(rename = "v")]
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pub value: Cid,
+64
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src/walk.rs
+64
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src/walk.rs
···
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//! Depth-first MST traversal
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use crate::mst::NodeEntry;
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use crate::mst::MstNode;
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use crate::Bytes;
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use crate::HashMap;
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use crate::disk::DiskStore;
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use crate::drive::MaybeProcessedBlock;
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use crate::mst::Node;
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use cid::Cid;
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use sha2::{Digest, Sha256};
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use std::convert::Infallible;
···
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}
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#[derive(Debug, Clone, Copy, PartialEq)]
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enum Depth {
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pub enum Depth {
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Root,
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Depth(u32),
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}
···
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Self::Root => Ok(None),
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Self::Depth(d) => d.checked_sub(1).ok_or(MstError::DepthUnderflow).map(Some),
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}
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}
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pub fn compute(key: &[u8]) -> u32 {
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let Depth::Depth(d) = Self::from_key(key) else {
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panic!("errr");
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};
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d
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}
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}
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fn push_from_node(stack: &mut Vec<Need>, node: &Node, parent_depth: Depth) -> Result<(), MstError> {
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fn push_from_node(stack: &mut Vec<Need>, node: &MstNode, parent_depth: Depth) -> Result<(), MstError> {
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// empty nodes are not allowed in the MST except in an empty MST
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if node.is_empty() {
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if parent_depth == Depth::Root {
···
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}
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}
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let mut entries = Vec::with_capacity(node.entries.len());
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let mut prefix = vec![];
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let mut this_depth = parent_depth.next_expected()?;
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for entry in &node.entries {
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let mut rkey = vec![];
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let pre_checked = prefix
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.get(..entry.prefix_len)
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.ok_or(MstError::EntryPrefixOutOfbounds)?;
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rkey.extend_from_slice(pre_checked);
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rkey.extend_from_slice(&entry.keysuffix);
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let Depth::Depth(key_depth) = Depth::from_key(&rkey) else {
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return Err(MstError::WrongDepth);
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};
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// this_depth is `none` if we are the deepest child (directly below root)
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// in that case we accept whatever highest depth is claimed
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let expected_depth = match this_depth {
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Some(d) => d,
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None => {
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this_depth = Some(key_depth);
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key_depth
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for entry in node.entries.iter().rev() {
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// ok this loop sucks now esp with depth checking
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// should keep the entries together with a shared depth on the rkey
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// ...maybe. skipping the absent trees is nice?
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match entry {
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NodeEntry::Value(cid, rkey) => {
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stack.push(Need::Record {
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rkey: String::from_utf8(rkey.to_vec())?,
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cid: *cid,
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});
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}
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NodeEntry::Tree(cid, depth) => {
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if let Some(expected) = this_depth {
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if *depth != expected {
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return Err(MstError::WrongDepth);
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}
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} else {
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// this_depth is `none` if we are the deepest child (directly below root)
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// in that case we accept whatever highest depth is claimed
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this_depth = Some(*depth);
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}
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stack.push(Need::Node {
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depth: Depth::Depth(*depth),
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cid: *cid,
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});
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}
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};
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// all keys we find should be this depth
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if key_depth != expected_depth {
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return Err(MstError::DepthUnderflow);
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}
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prefix = rkey.clone();
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entries.push(Need::Record {
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rkey: String::from_utf8(rkey)?,
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cid: entry.value,
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});
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if let Some(ref tree) = entry.tree {
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entries.push(Need::Node {
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depth: Depth::Depth(key_depth),
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cid: *tree,
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});
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}
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}
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entries.reverse();
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stack.append(&mut entries);
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let d = this_depth.ok_or(MstError::LostDepth)?;
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if let Some(tree) = node.left {
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stack.push(Need::Node {
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depth: Depth::Depth(d),
···
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let MaybeProcessedBlock::Raw(data) = block else {
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return Err(WalkError::BadCommitFingerprint);
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};
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let node = serde_ipld_dagcbor::from_slice::<Node>(&data)
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let node = serde_ipld_dagcbor::from_slice::<crate::mst::MstNode>(&data)
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.map_err(WalkError::BadCommit)?;
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// found node, make sure we remember
···
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let MaybeProcessedBlock::Raw(data) = block else {
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return Err(WalkError::BadCommitFingerprint);
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};
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let node = serde_ipld_dagcbor::from_slice::<Node>(&data)
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let node = serde_ipld_dagcbor::from_slice::<MstNode>(&data)
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.map_err(WalkError::BadCommit)?;
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// found node, make sure we remember
···
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}
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}
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#[test]
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fn test_push_empty_fails() {
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let empty_node = Node {
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left: None,
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entries: vec![],
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};
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let mut stack = vec![];
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let err = push_from_node(&mut stack, &empty_node, Depth::Depth(4));
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assert_eq!(err, Err(MstError::EmptyNode));
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}
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// #[test]
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// fn test_push_empty_fails() {
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// let empty_node = Node {
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// left: None,
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// entries: vec![],
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// };
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// let mut stack = vec![];
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// let err = push_from_node(&mut stack, &empty_node, Depth::Depth(4));
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// assert_eq!(err, Err(MstError::EmptyNode));
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// }
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#[test]
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fn test_push_one_node() {
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let node = Node {
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left: Some(cid1()),
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entries: vec![],
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};
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let mut stack = vec![];
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push_from_node(&mut stack, &node, Depth::Depth(4)).unwrap();
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assert_eq!(
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stack.last(),
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Some(Need::Node {
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depth: Depth::Depth(3),
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cid: cid1()
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})
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.as_ref()
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);
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}
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// #[test]
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// fn test_push_one_node() {
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// let node = Node {
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// left: Some(cid1()),
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// entries: vec![],
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// };
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// let mut stack = vec![];
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// push_from_node(&mut stack, &node, Depth::Depth(4)).unwrap();
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// assert_eq!(
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// stack.last(),
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// Some(Need::Node {
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// depth: Depth::Depth(3),
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// cid: cid1()
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// })
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// .as_ref()
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// );
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// }
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}