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-rw-r--r--src/table/merkle.rs352
1 files changed, 352 insertions, 0 deletions
diff --git a/src/table/merkle.rs b/src/table/merkle.rs
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+use std::convert::TryInto;
+use std::sync::Arc;
+use std::time::Duration;
+
+use futures::select;
+use futures_util::future::*;
+use log::{info, warn};
+use serde::{Deserialize, Serialize};
+use sled::transaction::{
+ ConflictableTransactionError, ConflictableTransactionResult, TransactionalTree,
+};
+use tokio::sync::{watch, Notify};
+
+use garage_util::background::BackgroundRunner;
+use garage_util::data::*;
+use garage_util::error::Error;
+
+// This modules partitions the data in 2**16 partitions, based on the top
+// 16 bits (two bytes) of item's partition keys' hashes.
+// It builds one Merkle tree for each of these 2**16 partitions.
+
+pub(crate) struct MerkleUpdater {
+ table_name: String,
+ background: Arc<BackgroundRunner>,
+
+ // Content of the todo tree: items where
+ // - key = the key of an item in the main table, ie hash(partition_key)+sort_key
+ // - value = the hash of the full serialized item, if present,
+ // or an empty vec if item is absent (deleted)
+ pub(crate) todo: sled::Tree,
+ pub(crate) todo_notify: Notify,
+
+ // Content of the merkle tree: items where
+ // - key = .bytes() for MerkleNodeKey
+ // - value = serialization of a MerkleNode, assumed to be MerkleNode::empty if not found
+ pub(crate) merkle_tree: sled::Tree,
+ empty_node_hash: Hash,
+}
+
+#[derive(Clone)]
+pub struct MerkleNodeKey {
+ // partition: first 16 bits (two bytes) of the partition_key's hash
+ pub partition: [u8; 2],
+
+ // prefix: a prefix for the hash of full keys, i.e. hash(hash(partition_key)+sort_key)
+ pub prefix: Vec<u8>,
+}
+
+#[derive(PartialEq, Eq, Debug, Serialize, Deserialize)]
+pub enum MerkleNode {
+ // The empty Merkle node
+ Empty,
+
+ // An intermediate Merkle tree node for a prefix
+ // Contains the hashes of the 256 possible next prefixes
+ Intermediate(Vec<(u8, Hash)>),
+
+ // A final node for an item
+ // Contains the full key of the item and the hash of the value
+ Leaf(Vec<u8>, Hash),
+}
+
+impl MerkleUpdater {
+ pub(crate) fn new(
+ table_name: String,
+ background: Arc<BackgroundRunner>,
+ todo: sled::Tree,
+ merkle_tree: sled::Tree,
+ ) -> Arc<Self> {
+ let empty_node_hash = blake2sum(&rmp_to_vec_all_named(&MerkleNode::Empty).unwrap()[..]);
+
+ Arc::new(Self {
+ table_name,
+ background,
+ todo,
+ todo_notify: Notify::new(),
+ merkle_tree,
+ empty_node_hash,
+ })
+ }
+
+ pub(crate) fn launch(self: &Arc<Self>) {
+ let self2 = self.clone();
+ self.background.spawn_worker(
+ format!("Merkle tree updater for {}", self.table_name),
+ |must_exit: watch::Receiver<bool>| self2.updater_loop(must_exit),
+ );
+ }
+
+ async fn updater_loop(
+ self: Arc<Self>,
+ mut must_exit: watch::Receiver<bool>,
+ ) -> Result<(), Error> {
+ while !*must_exit.borrow() {
+ if let Some(x) = self.todo.iter().next() {
+ match x {
+ Ok((key, valhash)) => {
+ if let Err(e) = self.update_item(&key[..], &valhash[..]) {
+ warn!("Error while updating Merkle tree item: {}", e);
+ }
+ }
+ Err(e) => {
+ warn!("Error while iterating on Merkle todo tree: {}", e);
+ tokio::time::delay_for(Duration::from_secs(10)).await;
+ }
+ }
+ } else {
+ select! {
+ _ = self.todo_notify.notified().fuse() => (),
+ _ = must_exit.recv().fuse() => (),
+ }
+ }
+ }
+ Ok(())
+ }
+
+ fn update_item(&self, k: &[u8], vhash_by: &[u8]) -> Result<(), Error> {
+ let khash = blake2sum(k);
+
+ let new_vhash = if vhash_by.len() == 0 {
+ None
+ } else {
+ let vhash_by: [u8; 32] = vhash_by
+ .try_into()
+ .map_err(|_| Error::Message(format!("Invalid value in Merkle todo table")))?;
+ Some(Hash::from(vhash_by))
+ };
+
+ let key = MerkleNodeKey {
+ partition: k[0..2].try_into().unwrap(),
+ prefix: vec![],
+ };
+ self.merkle_tree
+ .transaction(|tx| self.update_item_rec(tx, k, khash, &key, new_vhash))?;
+
+ let deleted = self
+ .todo
+ .compare_and_swap::<_, _, Vec<u8>>(k, Some(vhash_by), None)?
+ .is_ok();
+
+ if !deleted {
+ info!(
+ "Item not deleted from Merkle todo because it changed: {:?}",
+ k
+ );
+ }
+ Ok(())
+ }
+
+ fn update_item_rec(
+ &self,
+ tx: &TransactionalTree,
+ k: &[u8],
+ khash: Hash,
+ key: &MerkleNodeKey,
+ new_vhash: Option<Hash>,
+ ) -> ConflictableTransactionResult<Option<Hash>, Error> {
+ let i = key.prefix.len();
+ let mutate = match self.read_node_txn(tx, &key)? {
+ MerkleNode::Empty => {
+ if let Some(vhv) = new_vhash {
+ Some(MerkleNode::Leaf(k.to_vec(), vhv))
+ } else {
+ None
+ }
+ }
+ MerkleNode::Intermediate(mut children) => {
+ let key2 = key.next_key(khash);
+ if let Some(subhash) = self.update_item_rec(tx, k, khash, &key2, new_vhash)? {
+ if subhash == self.empty_node_hash {
+ intermediate_rm_child(&mut children, key2.prefix[i]);
+ } else {
+ intermediate_set_child(&mut children, key2.prefix[i], subhash);
+ }
+ if children.len() == 0 {
+ // should not happen
+ warn!("Replacing intermediate node with empty node, should not happen.");
+ Some(MerkleNode::Empty)
+ } else if children.len() == 1 {
+ // move node down to this level
+ let key_sub = key.add_byte(children[0].0);
+ let subnode = self.read_node_txn(tx, &key_sub)?;
+ tx.remove(key_sub.encode())?;
+ Some(subnode)
+ } else {
+ Some(MerkleNode::Intermediate(children))
+ }
+ } else {
+ None
+ }
+ }
+ MerkleNode::Leaf(exlf_key, exlf_hash) => {
+ if exlf_key == k {
+ match new_vhash {
+ Some(vhv) if vhv == exlf_hash => None,
+ Some(vhv) => Some(MerkleNode::Leaf(k.to_vec(), vhv)),
+ None => Some(MerkleNode::Empty),
+ }
+ } else {
+ if let Some(vhv) = new_vhash {
+ // Create two sub-nodes and replace by intermediary node
+ let (pos1, h1) = {
+ let key2 = key.next_key(blake2sum(&exlf_key[..]));
+ let subhash =
+ self.put_node_txn(tx, &key2, &MerkleNode::Leaf(exlf_key, exlf_hash))?;
+ (key2.prefix[i], subhash)
+ };
+ let (pos2, h2) = {
+ let key2 = key.next_key(khash);
+ let subhash =
+ self.put_node_txn(tx, &key2, &MerkleNode::Leaf(k.to_vec(), vhv))?;
+ (key2.prefix[i], subhash)
+ };
+ let mut int = vec![];
+ intermediate_set_child(&mut int, pos1, h1);
+ intermediate_set_child(&mut int, pos2, h2);
+ Some(MerkleNode::Intermediate(int))
+ } else {
+ None
+ }
+ }
+ }
+ };
+
+ if let Some(new_node) = mutate {
+ let hash = self.put_node_txn(tx, &key, &new_node)?;
+ Ok(Some(hash))
+ } else {
+ Ok(None)
+ }
+ }
+
+ // Merkle tree node manipulation
+
+ fn read_node_txn(
+ &self,
+ tx: &TransactionalTree,
+ k: &MerkleNodeKey,
+ ) -> ConflictableTransactionResult<MerkleNode, Error> {
+ let ent = tx.get(k.encode())?;
+ match ent {
+ None => Ok(MerkleNode::Empty),
+ Some(v) => Ok(rmp_serde::decode::from_read_ref::<_, MerkleNode>(&v[..])
+ .map_err(|e| ConflictableTransactionError::Abort(e.into()))?),
+ }
+ }
+
+ fn put_node_txn(
+ &self,
+ tx: &TransactionalTree,
+ k: &MerkleNodeKey,
+ v: &MerkleNode,
+ ) -> ConflictableTransactionResult<Hash, Error> {
+ if *v == MerkleNode::Empty {
+ tx.remove(k.encode())?;
+ Ok(self.empty_node_hash)
+ } else {
+ let vby = rmp_to_vec_all_named(v)
+ .map_err(|e| ConflictableTransactionError::Abort(e.into()))?;
+ let rethash = blake2sum(&vby[..]);
+ tx.insert(k.encode(), vby)?;
+ Ok(rethash)
+ }
+ }
+
+ pub(crate) fn read_node(
+ &self,
+ k: &MerkleNodeKey,
+ ) -> Result<MerkleNode, Error> {
+ let ent = self.merkle_tree.get(k.encode())?;
+ match ent {
+ None => Ok(MerkleNode::Empty),
+ Some(v) => Ok(rmp_serde::decode::from_read_ref::<_, MerkleNode>(&v[..])?)
+ }
+ }
+}
+
+impl MerkleNodeKey {
+ fn encode(&self) -> Vec<u8> {
+ let mut ret = Vec::with_capacity(2 + self.prefix.len());
+ ret.extend(&self.partition[..]);
+ ret.extend(&self.prefix[..]);
+ ret
+ }
+
+ pub fn next_key(&self, h: Hash) -> Self {
+ assert!(&h.as_slice()[0..self.prefix.len()] == &self.prefix[..]);
+ let mut s2 = self.clone();
+ s2.prefix.push(h.as_slice()[self.prefix.len()]);
+ s2
+ }
+
+ pub fn add_byte(&self, b: u8) -> Self {
+ let mut s2 = self.clone();
+ s2.prefix.push(b);
+ s2
+ }
+}
+
+fn intermediate_set_child(ch: &mut Vec<(u8, Hash)>, pos: u8, v: Hash) {
+ for i in 0..ch.len() {
+ if ch[i].0 == pos {
+ ch[i].1 = v;
+ return;
+ } else if ch[i].0 > pos {
+ ch.insert(i, (pos, v));
+ return;
+ }
+ }
+ ch.insert(ch.len(), (pos, v));
+}
+
+fn intermediate_rm_child(ch: &mut Vec<(u8, Hash)>, pos: u8) {
+ for i in 0..ch.len() {
+ if ch[i].0 == pos {
+ ch.remove(i);
+ return;
+ }
+ }
+}
+
+#[test]
+fn test_intermediate_aux() {
+ let mut v = vec![];
+
+ intermediate_set_child(&mut v, 12u8, [12u8; 32].into());
+ assert!(v == vec![(12u8, [12u8; 32].into())]);
+
+ intermediate_set_child(&mut v, 42u8, [42u8; 32].into());
+ assert!(v == vec![(12u8, [12u8; 32].into()), (42u8, [42u8; 32].into())]);
+
+ intermediate_set_child(&mut v, 4u8, [4u8; 32].into());
+ assert!(v == vec![(4u8, [4u8; 32].into()), (12u8, [12u8; 32].into()), (42u8, [42u8; 32].into())]);
+
+ intermediate_set_child(&mut v, 12u8, [8u8; 32].into());
+ assert!(v == vec![(4u8, [4u8; 32].into()), (12u8, [8u8; 32].into()), (42u8, [42u8; 32].into())]);
+
+ intermediate_set_child(&mut v, 6u8, [6u8; 32].into());
+ assert!(v == vec![(4u8, [4u8; 32].into()), (6u8, [6u8; 32].into()), (12u8, [8u8; 32].into()), (42u8, [42u8; 32].into())]);
+
+ intermediate_rm_child(&mut v, 42u8);
+ assert!(v == vec![(4u8, [4u8; 32].into()), (6u8, [6u8; 32].into()), (12u8, [8u8; 32].into())]);
+
+ intermediate_rm_child(&mut v, 11u8);
+ assert!(v == vec![(4u8, [4u8; 32].into()), (6u8, [6u8; 32].into()), (12u8, [8u8; 32].into())]);
+
+ intermediate_rm_child(&mut v, 6u8);
+ assert!(v == vec![(4u8, [4u8; 32].into()), (12u8, [8u8; 32].into())]);
+
+ intermediate_set_child(&mut v, 6u8, [7u8; 32].into());
+ assert!(v == vec![(4u8, [4u8; 32].into()), (6u8, [7u8; 32].into()), (12u8, [8u8; 32].into())]);
+}
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