Make transaction pool prune transactions only of canonical blocks (#6123)

* Make tx pool aware of retracted fork blocks

* Make it compile

* Update client/transaction-pool/src/lib.rs

Co-authored-by: Nikolay Volf <nikvolf@gmail.com>

* Fix doc test

* Simplify the implementation

* Send tree route as arc to prevent heavy clones

* Switch to use `ExtrinsicHash` to make it more clear

* Fix benchmark

Co-authored-by: Nikolay Volf <nikvolf@gmail.com>

substrate/client/api/src/backend.rs

@@ -67,8 +67,10 @@ pub struct ImportSummary<Block: BlockT> {
 	pub is_new_best: bool,
 	/// Optional storage changes.
 	pub storage_changes: Option<(StorageCollection, ChildStorageCollection)>,
-	/// Blocks that got retracted because of this one got imported.
-	pub retracted: Vec<Block::Hash>,
+	/// Tree route from old best to new best.
+	///
+	/// If `None`, there was no re-org while importing.
+	pub tree_route: Option<sp_blockchain::TreeRoute<Block>>,
 }
 
 /// Import operation wrapper

substrate/client/api/src/client.rs

@@ -16,7 +16,7 @@
 
 //! A set of APIs supported by the client along with their primitives.
 
-use std::{fmt, collections::HashSet};
+use std::{fmt, collections::HashSet, sync::Arc};
 use sp_core::storage::StorageKey;
 use sp_runtime::{
 	traits::{Block as BlockT, NumberFor},
@@ -234,8 +234,10 @@ pub struct BlockImportNotification<Block: BlockT> {
 	pub header: Block::Header,
 	/// Is this the new best block.
 	pub is_new_best: bool,
-	/// List of retracted blocks ordered by block number.
-	pub retracted: Vec<Block::Hash>,
+	/// Tree route from old best to new best.
+	///
+	/// If `None`, there was no re-org while importing.
+	pub tree_route: Option<Arc<sp_blockchain::TreeRoute<Block>>>,
 }
 
 /// Summary of a finalized block.