Prune leaves on finality (#1871)

* support multiple leaves at same height in leaves set

* prune leaves on finalization

* test leaves behavior in client-db

* fix no-std compilation

substrate/core/client/db/src/lib.rs

@@ -51,7 +51,7 @@ use state_machine::backend::Backend as StateBackend;
 use executor::RuntimeInfo;
 use state_machine::{CodeExecutor, DBValue};
 use crate::utils::{Meta, db_err, meta_keys, open_database, read_db, block_id_to_lookup_key, read_meta};
-use client::LeafSet;
+use client::leaves::{LeafSet, FinalizationDisplaced};
 use client::children;
 use state_db::StateDb;
 use crate::storage_cache::{CachingState, SharedCache, new_shared_cache};
@@ -714,11 +714,18 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 		header: &Block::Header,
 		last_finalized: Option<Block::Hash>,
 		justification: Option<Justification>,
+		finalization_displaced: &mut Option<FinalizationDisplaced<Block::Hash, NumberFor<Block>>>,
 	) -> Result<(Block::Hash, <Block::Header as HeaderT>::Number, bool, bool), client::error::Error> {
 		// TODO: ensure best chain contains this block.
 		let number = *header.number();
 		self.ensure_sequential_finalization(header, last_finalized)?;
-		self.note_finalized(transaction, header, *hash)?;
+		self.note_finalized(
+			transaction,
+			header,
+			*hash,
+			finalization_displaced,
+		)?;
+
 		if let Some(justification) = justification {
 			transaction.put(
 				columns::JUSTIFICATION,
@@ -767,10 +774,13 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 		-> Result<(), client::error::Error>
 	{
 		let mut transaction = DBTransaction::new();
+		let mut finalization_displaced_leaves = None;
+
 		operation.apply_aux(&mut transaction);
 
 		let mut meta_updates = Vec::new();
 		let mut last_finalized_hash = self.blockchain.meta.read().finalized_hash;
+
 		if !operation.finalized_blocks.is_empty() {
 			for (block, justification) in operation.finalized_blocks {
 				let block_hash = self.blockchain.expect_block_hash_from_id(&block)?;
@@ -782,6 +792,7 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 					&block_header,
 					Some(last_finalized_hash),
 					justification,
+					&mut finalization_displaced_leaves,
 				)?);
 				last_finalized_hash = block_hash;
 			}
@@ -846,7 +857,12 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 			if finalized {
 				// TODO: ensure best chain contains this block.
 				self.ensure_sequential_finalization(header, Some(last_finalized_hash))?;
-				self.note_finalized(&mut transaction, header, hash)?;
+				self.note_finalized(
+					&mut transaction,
+					header,
+					hash,
+					&mut finalization_displaced_leaves,
+				)?;
 			} else {
 				// canonicalize blocks which are old enough, regardless of finality.
 				self.force_delayed_canonicalize(&mut transaction, hash, *header.number())?
@@ -892,9 +908,16 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 
 		if let Some((number, hash, enacted, retracted, displaced_leaf, is_best)) = imported {
 			if let Err(e) = write_result {
+				let mut leaves = self.blockchain.leaves.write();
+				let mut undo = leaves.undo();
 				if let Some(displaced_leaf) = displaced_leaf {
-					self.blockchain.leaves.write().undo(displaced_leaf);
+					undo.undo_import(displaced_leaf);
 				}
+
+				if let Some(finalization_displaced) = finalization_displaced_leaves {
+					undo.undo_finalization(finalization_displaced);
+				}
+
 				return Err(e)
 			}
 
@@ -924,6 +947,7 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 		transaction: &mut DBTransaction,
 		f_header: &Block::Header,
 		f_hash: Block::Hash,
+		displaced: &mut Option<FinalizationDisplaced<Block::Hash, NumberFor<Block>>>
 	) -> Result<(), client::error::Error> where
 		Block: BlockT<Hash=H256>,
 	{
@@ -947,6 +971,12 @@ impl<Block: BlockT<Hash=H256>> Backend<Block> {
 			self.changes_tries_storage.prune(changes_trie_config, transaction, f_hash, f_num);
 		}
 
+		let new_displaced = self.blockchain.leaves.write().finalize_height(f_num);
+		match displaced {
+			x @ &mut None => *x = Some(new_displaced),
+			&mut Some(ref mut displaced) => displaced.merge(new_displaced),
+		}
+
 		Ok(())
 	}
 }
@@ -1036,22 +1066,27 @@ impl<Block> client::backend::Backend<Block, Blake2Hasher> for Backend<Block> whe
 		let mut transaction = DBTransaction::new();
 		let hash = self.blockchain.expect_block_hash_from_id(&block)?;
 		let header = self.blockchain.expect_header(block)?;
-		let commit = || {
+		let mut displaced = None;
+		let commit = |displaced| {
 			let (hash, number, is_best, is_finalized) = self.finalize_block_with_transaction(
 				&mut transaction,
 				&hash,
 				&header,
 				None,
 				justification,
+				displaced,
 			)?;
 			self.storage.db.write(transaction).map_err(db_err)?;
 			self.blockchain.update_meta(hash, number, is_best, is_finalized);
 			Ok(())
 		};
-		match commit() {
+		match commit(&mut displaced) {
 			Ok(()) => self.storage.state_db.apply_pending(),
 			e @ Err(_) => {
 				self.storage.state_db.revert_pending();
+				if let Some(displaced) = displaced {
+					self.blockchain.leaves.write().undo().undo_finalization(displaced);
+				}
 				return e;
 			}
 		}
@@ -1152,6 +1187,7 @@ mod tests {
 	use super::*;
 	use crate::columns;
 	use client::backend::Backend as BTrait;
+	use client::blockchain::Backend as BLBTrait;
 	use client::backend::BlockImportOperation as Op;
 	use runtime_primitives::testing::{Header, Block as RawBlock, ExtrinsicWrapper};
 	use runtime_primitives::traits::{Hash, BlakeTwo256};
@@ -1789,8 +1825,6 @@ mod tests {
 				BlockId::Hash(block1),
 			).unwrap();
 
-			println!("{:?}", tree_route);
-
 			assert_eq!(tree_route.common_block().hash, block0);
 			assert!(tree_route.retracted().is_empty());
 			assert_eq!(tree_route.enacted().iter().map(|r| r.hash).collect::<Vec<_>>(), vec![block1]);
@@ -1815,6 +1849,30 @@ mod tests {
 		test_client::trait_tests::test_blockchain_query_by_number_gets_canonical(backend);
 	}
 
+	#[test]
+	fn test_leaves_pruned_on_finality() {
+		let backend: Backend<Block> = Backend::new_test(10, 10);
+		let block0 = insert_header(&backend, 0, Default::default(), Default::default(), Default::default());
+
+		let block1_a = insert_header(&backend, 1, block0, Default::default(), Default::default());
+		let block1_b = insert_header(&backend, 1, block0, Default::default(), [1; 32].into());
+		let block1_c = insert_header(&backend, 1, block0, Default::default(), [2; 32].into());
+
+		assert_eq!(backend.blockchain().leaves().unwrap(), vec![block1_a, block1_b, block1_c]);
+
+		let block2_a = insert_header(&backend, 2, block1_a, Default::default(), Default::default());
+		let block2_b = insert_header(&backend, 2, block1_b, Default::default(), Default::default());
+		let block2_c = insert_header(&backend, 2, block1_b, Default::default(), [1; 32].into());
+
+		assert_eq!(backend.blockchain().leaves().unwrap(), vec![block2_a, block2_b, block2_c, block1_c]);
+
+		backend.finalize_block(BlockId::hash(block1_a), None).unwrap();
+		backend.finalize_block(BlockId::hash(block2_a), None).unwrap();
+
+		// leaves at same height stay. Leaves at lower heights pruned.
+		assert_eq!(backend.blockchain().leaves().unwrap(), vec![block2_a, block2_b, block2_c]);
+	}
+
 	#[test]
 	fn test_aux() {
 		let backend: Backend<test_client::runtime::Block> = Backend::new_test(0, 0);

substrate/core/client/db/src/light.rs

@@ -24,7 +24,8 @@ use kvdb::{KeyValueDB, DBTransaction};
 use client::backend::{AuxStore, NewBlockState};
 use client::blockchain::{BlockStatus, Cache as BlockchainCache,
 	HeaderBackend as BlockchainHeaderBackend, Info as BlockchainInfo};
-use client::{cht, LeafSet};
+use client::cht;
+use client::leaves::{LeafSet, FinalizationDisplaced};
 use client::error::{ErrorKind as ClientErrorKind, Result as ClientResult};
 use client::light::blockchain::Storage as LightBlockchainStorage;
 use parity_codec::{Decode, Encode};
@@ -250,6 +251,7 @@ impl<Block: BlockT> LightStorage<Block> {
 		transaction: &mut DBTransaction,
 		header: &Block::Header,
 		hash: Block::Hash,
+		displaced: &mut Option<FinalizationDisplaced<Block::Hash, NumberFor<Block>>>,
 	) -> ClientResult<()> {
 		let meta = self.meta.read();
 		if &meta.finalized_hash != header.parent_hash() {
@@ -311,6 +313,12 @@ impl<Block: BlockT> LightStorage<Block> {
 			}
 		}
 
+		let new_displaced = self.leaves.write().finalize_height(header.number().clone());
+		match displaced {
+			x @ &mut None => *x = Some(new_displaced),
+			&mut Some(ref mut displaced) => displaced.merge(new_displaced),
+		}
+
 		Ok(())
 	}
 
@@ -366,6 +374,7 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 		leaf_state: NewBlockState,
 		aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	) -> ClientResult<()> {
+		let mut finalization_displaced_leaves = None;
 		let mut transaction = DBTransaction::new();
 
 		let hash = header.hash();
@@ -405,7 +414,12 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 		};
 
 		if finalized {
-			self.note_finalized(&mut transaction, &header, hash)?;
+			self.note_finalized(
+				&mut transaction,
+				&header,
+				hash,
+				&mut finalization_displaced_leaves,
+			)?;
 		}
 
 		{
@@ -425,10 +439,18 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 			debug!("Light DB Commit {:?} ({})", hash, number);
 			let write_result = self.db.write(transaction).map_err(db_err);
 			if let Err(e) = write_result {
+				let mut leaves = self.leaves.write();
+				let mut undo = leaves.undo();
+
 				// revert leaves set update if there was one.
 				if let Some(displaced_leaf) = displaced_leaf {
-					leaves.undo(displaced_leaf);
+					undo.undo_import(displaced_leaf);
 				}
+
+				if let Some(finalization_displaced) = finalization_displaced_leaves {
+					undo.undo_finalization(finalization_displaced);
+				}
+
 				return Err(e);
 			}
 
@@ -464,10 +486,11 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 
 	fn finalize_header(&self, id: BlockId<Block>) -> ClientResult<()> {
 		if let Some(header) = self.header(id)? {
+			let mut displaced = None;
 			let mut transaction = DBTransaction::new();
 			let hash = header.hash();
 			let number = *header.number();
-			self.note_finalized(&mut transaction, &header, hash.clone())?;
+			self.note_finalized(&mut transaction, &header, hash.clone(), &mut displaced)?;
 			{
 				let mut cache = self.cache.0.write();
 				let cache_ops = cache.transaction(&mut transaction)
@@ -477,7 +500,12 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 					)?
 					.into_ops();
 
-				self.db.write(transaction).map_err(db_err)?;
+				if let Err(e) = self.db.write(transaction).map_err(db_err) {
+					if let Some(displaced) = displaced {
+						self.leaves.write().undo().undo_finalization(displaced);
+					}
+					return Err(e);
+				}
 				cache.commit(cache_ops);
 			}
 			self.update_meta(hash, header.number().clone(), false, true);
@@ -940,4 +968,28 @@ pub(crate) mod tests {
 		assert_eq!(db.get_aux(&[2]).unwrap(), Some(vec![102]));
 		assert_eq!(db.get_aux(&[3]).unwrap(), Some(vec![103]));
 	}
+
+	#[test]
+	fn test_leaves_pruned_on_finality() {
+		let db = LightStorage::<Block>::new_test();
+		let block0 = insert_final_block(&db, None, || default_header(&Default::default(), 0));
+
+		let block1_a = insert_block(&db, None, || default_header(&block0, 1));
+		let block1_b = insert_block(&db, None, || header_with_extrinsics_root(&block0, 1, [1; 32].into()));
+		let block1_c = insert_block(&db, None, || header_with_extrinsics_root(&block0, 1, [2; 32].into()));
+
+		assert_eq!(db.leaves.read().hashes(), vec![block1_a, block1_b, block1_c]);
+
+		let block2_a = insert_block(&db, None, || default_header(&block1_a, 2));
+		let block2_b = insert_block(&db, None, || header_with_extrinsics_root(&block1_b, 2, [1; 32].into()));
+		let block2_c = insert_block(&db, None, || header_with_extrinsics_root(&block1_b, 2, [2; 32].into()));
+
+		assert_eq!(db.leaves.read().hashes(), vec![block2_a, block2_b, block2_c, block1_c]);
+
+		db.finalize_header(BlockId::hash(block1_a)).unwrap();
+		db.finalize_header(BlockId::hash(block2_a)).unwrap();
+
+		// leaves at same height stay. Leaves at lower heights pruned.
+		assert_eq!(db.leaves.read().hashes(), vec![block2_a, block2_b, block2_c]);
+	}
 }