Availability/Extrinsic store (#465)

polkadot/availability-store/src/lib.rs

@@ -0,0 +1,258 @@
+// Copyright 2018 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Persistent database for parachain data.
+
+extern crate polkadot_primitives;
+extern crate parking_lot;
+extern crate substrate_codec as codec;
+extern crate substrate_primitives;
+extern crate kvdb;
+extern crate kvdb_rocksdb;
+extern crate kvdb_memorydb;
+
+#[macro_use]
+extern crate log;
+
+use codec::{Encode, Decode};
+use kvdb::{KeyValueDB, DBTransaction};
+use kvdb_rocksdb::{Database, DatabaseConfig};
+use polkadot_primitives::Hash;
+use polkadot_primitives::parachain::{Id as ParaId, BlockData, Extrinsic};
+
+use std::collections::HashSet;
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::io;
+
+mod columns {
+	pub const DATA: Option<u32> = Some(0);
+	pub const META: Option<u32> = Some(1);
+	pub const NUM_COLUMNS: u32 = 2;
+}
+
+/// Configuration for the availability store.
+pub struct Config {
+	/// Cache size in bytes. If `None` default is used.
+	pub cache_size: Option<usize>,
+	/// Path to the database.
+	pub path: PathBuf,
+}
+
+/// Some data to keep available.
+pub struct Data {
+	/// The relay chain parent hash this should be localized to.
+	pub relay_parent: Hash,
+	/// The parachain index for this candidate.
+	pub parachain_id: ParaId,
+	/// Unique candidate receipt hash.
+	pub candidate_hash: Hash,
+	/// Block data.
+	pub block_data: BlockData,
+	/// Extrinsic data.
+	pub extrinsic: Option<Extrinsic>,
+}
+
+fn extract_io_err(err: ::kvdb::Error) -> io::Error {
+	match err {
+		::kvdb::Error(::kvdb::ErrorKind::Io(io_err), _) => io_err,
+		::kvdb::Error(::kvdb::ErrorKind::Msg(msg), _) => io::Error::new(
+			io::ErrorKind::Other,
+			msg,
+		),
+		x => io::Error::new(
+			io::ErrorKind::Other,
+			format!("Unexpected error variant: {:?}", x), // only necessary because of nonexaustive match.
+		)
+	}
+}
+
+fn block_data_key(relay_parent: &Hash, candidate_hash: &Hash) -> Vec<u8> {
+	(relay_parent, candidate_hash, 0i8).encode()
+}
+
+fn extrinsic_key(relay_parent: &Hash, candidate_hash: &Hash) -> Vec<u8> {
+	(relay_parent, candidate_hash, 1i8).encode()
+}
+
+/// Handle to the availability store.
+#[derive(Clone)]
+pub struct Store {
+	inner: Arc<KeyValueDB>,
+}
+
+impl Store {
+	/// Create a new `Store` with given config on disk.
+	pub fn new(config: Config) -> io::Result<Self> {
+		let mut db_config = DatabaseConfig::with_columns(Some(columns::NUM_COLUMNS));
+		db_config.memory_budget = config.cache_size;
+		db_config.wal = true;
+
+		let path = config.path.to_str().ok_or_else(|| io::Error::new(
+			io::ErrorKind::Other,
+			format!("Bad database path: {:?}", config.path),
+		))?;
+
+		let db = Database::open(&db_config, &path).map_err(extract_io_err)?;
+
+		Ok(Store {
+			inner: Arc::new(db),
+		})
+	}
+
+	/// Create a new `Store` in-memory. Useful for tests.
+	pub fn new_in_memory() -> Self {
+		Store {
+			inner: Arc::new(::kvdb_memorydb::create(::columns::NUM_COLUMNS)),
+		}
+	}
+
+	/// Make some data available provisionally.
+	pub fn make_available(&self, data: Data) -> io::Result<()> {
+		let mut tx = DBTransaction::new();
+
+		// note the meta key.
+		let mut v = match self.inner.get(columns::META, &*data.relay_parent) {
+			Ok(Some(raw)) => Vec::decode(&mut &raw[..]).expect("all stored data serialized correctly; qed"),
+			Ok(None) => Vec::new(),
+			Err(e) => {
+				warn!(target: "availability", "Error reading from availability store: {:?}", e);
+				Vec::new()
+			}
+		};
+
+		v.push(data.candidate_hash);
+		tx.put_vec(columns::META, &data.relay_parent[..], v.encode());
+
+		tx.put_vec(
+			columns::DATA,
+			block_data_key(&data.relay_parent, &data.candidate_hash).as_slice(),
+			data.block_data.encode()
+		);
+
+		if let Some(_extrinsic) = data.extrinsic {
+			tx.put_vec(
+				columns::DATA,
+				extrinsic_key(&data.relay_parent, &data.candidate_hash).as_slice(),
+				vec![],
+			);
+		}
+
+		self.inner.write(tx).map_err(extract_io_err)
+	}
+
+	/// Note that a set of candidates have been included in a finalized block with given hash and parent hash.
+	pub fn candidates_finalized(&self, parent: Hash, finalized_candidates: HashSet<Hash>) -> io::Result<()> {
+		let mut tx = DBTransaction::new();
+
+		let v = match self.inner.get(columns::META, &parent[..]) {
+			Ok(Some(raw)) => Vec::decode(&mut &raw[..]).expect("all stored data serialized correctly; qed"),
+			Ok(None) => Vec::new(),
+			Err(e) => {
+				warn!(target: "availability", "Error reading from availability store: {:?}", e);
+				Vec::new()
+			}
+		};
+		tx.delete(columns::META, &parent[..]);
+
+		for candidate_hash in v {
+			if !finalized_candidates.contains(&candidate_hash) {
+				tx.delete(columns::DATA, block_data_key(&parent, &candidate_hash).as_slice());
+				tx.delete(columns::DATA, extrinsic_key(&parent, &candidate_hash).as_slice());
+			}
+		}
+
+		self.inner.write(tx).map_err(extract_io_err)
+	}
+
+	/// Query block data.
+	pub fn block_data(&self, relay_parent: Hash, candidate_hash: Hash) -> Option<BlockData> {
+		let encoded_key = block_data_key(&relay_parent, &candidate_hash);
+		match self.inner.get(columns::DATA, &encoded_key[..]) {
+			Ok(Some(raw)) => Some(
+				BlockData::decode(&mut &raw[..]).expect("all stored data serialized correctly; qed")
+			),
+			Ok(None) => None,
+			Err(e) => {
+				warn!(target: "availability", "Error reading from availability store: {:?}", e);
+				None
+			}
+		}
+	}
+
+	/// Query extrinsic data.
+	pub fn extrinsic(&self, relay_parent: Hash, candidate_hash: Hash) -> Option<Extrinsic> {
+		let encoded_key = extrinsic_key(&relay_parent, &candidate_hash);
+		match self.inner.get(columns::DATA, &encoded_key[..]) {
+			Ok(Some(_raw)) => Some(Extrinsic),
+			Ok(None) => None,
+			Err(e) => {
+				warn!(target: "availability", "Error reading from availability store: {:?}", e);
+				None
+			}
+		}
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn finalization_removes_unneeded() {
+		let relay_parent = [1; 32].into();
+
+		let para_id_1 = 5.into();
+		let para_id_2 = 6.into();
+
+		let candidate_1 = [2; 32].into();
+		let candidate_2 = [3; 32].into();
+
+		let block_data_1 = BlockData(vec![1, 2, 3]);
+		let block_data_2 = BlockData(vec![4, 5, 6]);
+
+		let store = Store::new_in_memory();
+		store.make_available(Data {
+			relay_parent,
+			parachain_id: para_id_1,
+			candidate_hash: candidate_1,
+			block_data: block_data_1.clone(),
+			extrinsic: Some(Extrinsic),
+		}).unwrap();
+
+		store.make_available(Data {
+			relay_parent,
+			parachain_id: para_id_2,
+			candidate_hash: candidate_2,
+			block_data: block_data_2.clone(),
+			extrinsic: Some(Extrinsic),
+		}).unwrap();
+
+		assert_eq!(store.block_data(relay_parent, candidate_1).unwrap(), block_data_1);
+		assert_eq!(store.block_data(relay_parent, candidate_2).unwrap(), block_data_2);
+
+		assert!(store.extrinsic(relay_parent, candidate_1).is_some());
+		assert!(store.extrinsic(relay_parent, candidate_2).is_some());
+
+		store.candidates_finalized(relay_parent, [candidate_1].iter().cloned().collect()).unwrap();
+
+		assert_eq!(store.block_data(relay_parent, candidate_1).unwrap(), block_data_1);
+		assert!(store.block_data(relay_parent, candidate_2).is_none());
+
+		assert!(store.extrinsic(relay_parent, candidate_1).is_some());
+		assert!(store.extrinsic(relay_parent, candidate_2).is_none());
+	}
+}