Revert "Fix block pruning (#13323)"

This reverts commit a93d2ce.

Author: Ross Bulat

client/db/src/lib.rs

@@ -1806,13 +1806,7 @@ impl<Block: BlockT> Backend<Block> {
 		}
 
 		let new_displaced = self.blockchain.leaves.write().finalize_height(f_num);
-		self.prune_blocks(
-			transaction,
-			f_num,
-			f_hash,
-			&new_displaced,
-			current_transaction_justifications,
-		)?;
+		self.prune_blocks(transaction, f_num, &new_displaced, current_transaction_justifications)?;
 
 		Ok(())
 	}
@@ -1821,7 +1815,6 @@ impl<Block: BlockT> Backend<Block> {
 		&self,
 		transaction: &mut Transaction<DbHash>,
 		finalized_number: NumberFor<Block>,
-		finalized_hash: Block::Hash,
 		displaced: &FinalizationOutcome<Block::Hash, NumberFor<Block>>,
 		current_transaction_justifications: &mut HashMap<Block::Hash, Justification>,
 	) -> ClientResult<()> {
@@ -1850,10 +1843,10 @@ impl<Block: BlockT> Backend<Block> {
 
 					self.prune_block(transaction, BlockId::<Block>::number(number))?;
 				}
-				self.prune_displaced_branches(transaction, finalized_hash, displaced)?;
+				self.prune_displaced_branches(transaction, finalized_number, displaced)?;
 			},
 			BlocksPruning::KeepFinalized => {
-				self.prune_displaced_branches(transaction, finalized_hash, displaced)?;
+				self.prune_displaced_branches(transaction, finalized_number, displaced)?;
 			},
 		}
 		Ok(())
@@ -1862,21 +1855,28 @@ impl<Block: BlockT> Backend<Block> {
 	fn prune_displaced_branches(
 		&self,
 		transaction: &mut Transaction<DbHash>,
-		finalized: Block::Hash,
+		finalized: NumberFor<Block>,
 		displaced: &FinalizationOutcome<Block::Hash, NumberFor<Block>>,
 	) -> ClientResult<()> {
 		// Discard all blocks from displaced branches
 		for h in displaced.leaves() {
-			match sp_blockchain::tree_route(&self.blockchain, *h, finalized) {
-				Ok(tree_route) =>
-					for r in tree_route.retracted() {
-						self.blockchain.insert_persisted_body_if_pinned(r.hash)?;
-						self.prune_block(transaction, BlockId::<Block>::hash(r.hash))?;
+			let mut number = finalized;
+			let mut hash = *h;
+			// Follow displaced chains back until we reach a finalized block.
+			// Since leaves are discarded due to finality, they can't have parents
+			// that are canonical, but not yet finalized. So we stop deleting as soon as
+			// we reach canonical chain.
+			while self.blockchain.hash(number)? != Some(hash) {
+				match self.blockchain.header(hash)? {
+					Some(header) => {
+						self.blockchain.insert_persisted_body_if_pinned(hash)?;
+
+						self.prune_block(transaction, BlockId::<Block>::hash(hash))?;
+						number = header.number().saturating_sub(One::one());
+						hash = *header.parent_hash();
 					},
-				Err(sp_blockchain::Error::UnknownBlock(_)) => {
-					// Sometimes routes can't be calculated. E.g. after warp sync.
-				},
-				Err(e) => Err(e)?,
+					None => break,
+				}
 			}
 		}
 		Ok(())
@@ -3569,50 +3569,6 @@ pub(crate) mod tests {
 		assert_eq!(Some(vec![4.into()]), bc.body(blocks[4]).unwrap());
 	}
 
-	#[test]
-	fn prune_blocks_on_finalize_and_reorg() {
-		//	0 - 1b
-		//	\ - 1a - 2a - 3a
-		//	     \ - 2b
-
-		let backend = Backend::<Block>::new_test_with_tx_storage(BlocksPruning::Some(10), 10);
-
-		let make_block = |index, parent, val: u64| {
-			insert_block(&backend, index, parent, None, H256::random(), vec![val.into()], None)
-				.unwrap()
-		};
-
-		let block_0 = make_block(0, Default::default(), 0x00);
-		let block_1a = make_block(1, block_0, 0x1a);
-		let block_1b = make_block(1, block_0, 0x1b);
-		let block_2a = make_block(2, block_1a, 0x2a);
-		let block_2b = make_block(2, block_1a, 0x2b);
-		let block_3a = make_block(3, block_2a, 0x3a);
-
-		// Make sure 1b is head
-		let mut op = backend.begin_operation().unwrap();
-		backend.begin_state_operation(&mut op, block_0).unwrap();
-		op.mark_head(block_1b).unwrap();
-		backend.commit_operation(op).unwrap();
-
-		// Finalize 3a
-		let mut op = backend.begin_operation().unwrap();
-		backend.begin_state_operation(&mut op, block_0).unwrap();
-		op.mark_head(block_3a).unwrap();
-		op.mark_finalized(block_1a, None).unwrap();
-		op.mark_finalized(block_2a, None).unwrap();
-		op.mark_finalized(block_3a, None).unwrap();
-		backend.commit_operation(op).unwrap();
-
-		let bc = backend.blockchain();
-		assert_eq!(None, bc.body(block_1b).unwrap());
-		assert_eq!(None, bc.body(block_2b).unwrap());
-		assert_eq!(Some(vec![0x00.into()]), bc.body(block_0).unwrap());
-		assert_eq!(Some(vec![0x1a.into()]), bc.body(block_1a).unwrap());
-		assert_eq!(Some(vec![0x2a.into()]), bc.body(block_2a).unwrap());
-		assert_eq!(Some(vec![0x3a.into()]), bc.body(block_3a).unwrap());
-	}
-
 	#[test]
 	fn indexed_data_block_body() {
 		let backend = Backend::<Block>::new_test_with_tx_storage(BlocksPruning::Some(1), 10);