Merge branch 'dev-0.2'

1 files changed, 454 insertions, 0 deletions

diff --git a/src/table/merkle.rs b/src/table/merkle.rs
new file mode 100644
index 00000000..3001786f
--- /dev/null
+++ b/src/table/merkle.rs
@@ -0,0 +1,454 @@
+use std::sync::Arc;
+use std::time::Duration;
+
+use futures::select;
+use futures_util::future::*;
+use log::{debug, warn};
+use serde::{Deserialize, Serialize};
+use sled::transaction::{
+	ConflictableTransactionError, ConflictableTransactionResult, TransactionalTree,
+};
+use tokio::sync::watch;
+
+use garage_util::background::BackgroundRunner;
+use garage_util::data::*;
+use garage_util::error::Error;
+
+use garage_rpc::ring::*;
+
+use crate::data::*;
+use crate::replication::*;
+use crate::schema::*;
+
+// 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 struct MerkleUpdater<F: TableSchema, R: TableReplication> {
+	data: Arc<TableData<F, R>>,
+
+	// 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)
+	// Fields in data:
+	//		pub(crate) merkle_todo: sled::Tree,
+	//		pub(crate) merkle_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
+	// Field in data:
+	//		pub(crate) merkle_tree: sled::Tree,
+	empty_node_hash: Hash,
+}
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct MerkleNodeKey {
+	// partition number
+	pub partition: Partition,
+
+	// prefix: a prefix for the hash of full keys, i.e. hash(hash(partition_key)+sort_key)
+	#[serde(with = "serde_bytes")]
+	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<F, R> MerkleUpdater<F, R>
+where
+	F: TableSchema + 'static,
+	R: TableReplication + 'static,
+{
+	pub(crate) fn launch(background: &BackgroundRunner, data: Arc<TableData<F, R>>) -> Arc<Self> {
+		let empty_node_hash = blake2sum(&rmp_to_vec_all_named(&MerkleNode::Empty).unwrap()[..]);
+
+		let ret = Arc::new(Self {
+			data,
+			empty_node_hash,
+		});
+
+		let ret2 = ret.clone();
+		background.spawn_worker(
+			format!("Merkle tree updater for {}", ret.data.name),
+			|must_exit: watch::Receiver<bool>| ret2.updater_loop(must_exit),
+		);
+
+		ret
+	}
+
+	async fn updater_loop(self: Arc<Self>, mut must_exit: watch::Receiver<bool>) {
+		while !*must_exit.borrow() {
+			if let Some(x) = self.data.merkle_todo.iter().next() {
+				match x {
+					Ok((key, valhash)) => {
+						if let Err(e) = self.update_item(&key[..], &valhash[..]) {
+							warn!(
+								"({}) Error while updating Merkle tree item: {}",
+								self.data.name, e
+							);
+						}
+					}
+					Err(e) => {
+						warn!(
+							"({}) Error while iterating on Merkle todo tree: {}",
+							self.data.name, e
+						);
+						tokio::time::sleep(Duration::from_secs(10)).await;
+					}
+				}
+			} else {
+				select! {
+					_ = self.data.merkle_todo_notify.notified().fuse() => (),
+					_ = must_exit.changed().fuse() => (),
+				}
+			}
+		}
+	}
+
+	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 {
+			Some(Hash::try_from(&vhash_by[..]).unwrap())
+		};
+
+		let key = MerkleNodeKey {
+			partition: self
+				.data
+				.replication
+				.partition_of(&Hash::try_from(&k[0..32]).unwrap()),
+			prefix: vec![],
+		};
+		self.data
+			.merkle_tree
+			.transaction(|tx| self.update_item_rec(tx, k, &khash, &key, new_vhash))?;
+
+		let deleted = self
+			.data
+			.merkle_todo
+			.compare_and_swap::<_, _, Vec<u8>>(k, Some(vhash_by), None)?
+			.is_ok();
+
+		if !deleted {
+			debug!(
+				"({}) Item not deleted from Merkle todo because it changed: {:?}",
+				self.data.name, 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();
+
+		// Read node at current position (defined by the prefix stored in key)
+		// Calculate an update to apply to this node
+		// This update is an Option<_>, so that it is None if the update is a no-op
+		// and we can thus skip recalculating and re-storing everything
+		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 {
+					// Nothing to do, keep empty node
+					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)? {
+					// Subtree changed, update this node as well
+					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.",
+							self.data.name
+						);
+						Some(MerkleNode::Empty)
+					} else if children.len() == 1 {
+						// We now have a single node (case when the update deleted one of only two
+						// children). If that node is a leaf, move it to this level.
+						let key_sub = key.add_byte(children[0].0);
+						let subnode = self.read_node_txn(tx, &key_sub)?;
+						match subnode {
+							MerkleNode::Empty => {
+								warn!("({}) Single subnode in tree is empty Merkle node", self.data.name);
+								Some(MerkleNode::Empty)
+							}
+							MerkleNode::Intermediate(_) => {
+								Some(MerkleNode::Intermediate(children))
+							}
+							x @ MerkleNode::Leaf(_, _) => {
+								tx.remove(key_sub.encode())?;
+								Some(x)
+							}
+						}
+					} else {
+						Some(MerkleNode::Intermediate(children))
+					}
+				} else {
+					// Subtree not changed, nothing to do
+					None
+				}
+			}
+			MerkleNode::Leaf(exlf_k, exlf_vhash) => {
+				if exlf_k == k {
+					// This leaf is for the same key that the one we are updating
+					match new_vhash {
+						Some(vhv) if vhv == exlf_vhash => None,
+						Some(vhv) => Some(MerkleNode::Leaf(k.to_vec(), vhv)),
+						None => Some(MerkleNode::Empty),
+					}
+				} else {
+					// This is an only leaf for another key
+					if new_vhash.is_some() {
+						// Move that other key to a subnode, create another subnode for our
+						// insertion and replace current node by an intermediary node
+						let mut int = vec![];
+
+						let exlf_khash = blake2sum(&exlf_k[..]);
+						assert_eq!(khash.as_slice()[..i], exlf_khash.as_slice()[..i]);
+
+						{
+							let exlf_subkey = key.next_key(&exlf_khash);
+							let exlf_sub_hash = self.update_item_rec(tx, &exlf_k[..], &exlf_khash, &exlf_subkey, Some(exlf_vhash))?.unwrap();
+							intermediate_set_child(&mut int, exlf_subkey.prefix[i], exlf_sub_hash);
+							assert_eq!(int.len(), 1);
+						}
+
+						{
+							let key2 = key.next_key(khash);
+							let subhash = self.update_item_rec(tx, k, khash, &key2, new_vhash)?.unwrap();
+							intermediate_set_child(&mut int, key2.prefix[i], subhash);
+							if exlf_khash.as_slice()[i] == khash.as_slice()[i] {
+								assert_eq!(int.len(), 1);
+							} else {
+								assert_eq!(int.len(), 2);
+							}
+						}
+						Some(MerkleNode::Intermediate(int))
+					} else {
+						// Nothing to do, we don't want to insert this value because it is None,
+						// and we don't want to change the other value because it's for something
+						// 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())?;
+		MerkleNode::decode_opt(ent).map_err(ConflictableTransactionError::Abort)
+	}
+
+	fn put_node_txn(
+		&self,
+		tx: &TransactionalTree,
+		k: &MerkleNodeKey,
+		v: &MerkleNode,
+	) -> ConflictableTransactionResult<Hash, Error> {
+		trace!("Put Merkle node: {:?} => {:?}", k, v);
+		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)
+		}
+	}
+
+	// Access a node in the Merkle tree, used by the sync protocol
+	pub(crate) fn read_node(&self, k: &MerkleNodeKey) -> Result<MerkleNode, Error> {
+		let ent = self.data.merkle_tree.get(k.encode())?;
+		MerkleNode::decode_opt(ent)
+	}
+
+	pub fn merkle_tree_len(&self) -> usize {
+		self.data.merkle_tree.len()
+	}
+
+	pub fn todo_len(&self) -> usize {
+		self.data.merkle_todo.len()
+	}
+}
+
+impl MerkleNodeKey {
+	fn encode(&self) -> Vec<u8> {
+		let mut ret = Vec::with_capacity(2 + self.prefix.len());
+		ret.extend(&u16::to_be_bytes(self.partition)[..]);
+		ret.extend(&self.prefix[..]);
+		ret
+	}
+
+	pub fn next_key(&self, h: &Hash) -> Self {
+		assert_eq!(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
+	}
+}
+
+impl MerkleNode {
+	fn decode_opt(ent: Option<sled::IVec>) -> Result<Self, Error> {
+		match ent {
+			None => Ok(MerkleNode::Empty),
+			Some(v) => Ok(rmp_serde::decode::from_read_ref::<_, MerkleNode>(&v[..])?),
+		}
+	}
+
+	pub fn is_empty(&self) -> bool {
+		*self == MerkleNode::Empty
+	}
+}
+
+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.push((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_eq!(v, vec![(12u8, [12u8; 32].into())]);
+
+	intermediate_set_child(&mut v, 42u8, [42u8; 32].into());
+	assert_eq!(
+		v,
+		vec![(12u8, [12u8; 32].into()), (42u8, [42u8; 32].into())]
+	);
+
+	intermediate_set_child(&mut v, 4u8, [4u8; 32].into());
+	assert_eq!(
+		v,
+		vec![
+			(4u8, [4u8; 32].into()),
+			(12u8, [12u8; 32].into()),
+			(42u8, [42u8; 32].into())
+		]
+	);
+
+	intermediate_set_child(&mut v, 12u8, [8u8; 32].into());
+	assert_eq!(
+		v,
+		vec![
+			(4u8, [4u8; 32].into()),
+			(12u8, [8u8; 32].into()),
+			(42u8, [42u8; 32].into())
+		]
+	);
+
+	intermediate_set_child(&mut v, 6u8, [6u8; 32].into());
+	assert_eq!(
+		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_eq!(
+		v,
+		vec![
+			(4u8, [4u8; 32].into()),
+			(6u8, [6u8; 32].into()),
+			(12u8, [8u8; 32].into())
+		]
+	);
+
+	intermediate_rm_child(&mut v, 11u8);
+	assert_eq!(
+		v,
+		vec![
+			(4u8, [4u8; 32].into()),
+			(6u8, [6u8; 32].into()),
+			(12u8, [8u8; 32].into())
+		]
+	);
+
+	intermediate_rm_child(&mut v, 6u8);
+	assert_eq!(v, vec![(4u8, [4u8; 32].into()), (12u8, [8u8; 32].into())]);
+
+	intermediate_set_child(&mut v, 6u8, [7u8; 32].into());
+	assert_eq!(
+		v,
+		vec![
+			(4u8, [4u8; 32].into()),
+			(6u8, [7u8; 32].into()),
+			(12u8, [8u8; 32].into())
+		]
+	);
+}