TransactionInvalidationTracker (#1544)

* TransactionInvalidationTracker

* TransacitonInvalidationTracker -> TransactionTracker

* change sign_transaction method

* clippy and spelling

* removed comment

* more transactiontracker tests

* stalls_when_transaction_tracker_returns_error

* remove test code

* remove "impl TransactionTracker for ()"

* enum TrackedTransactionStatus

* test TransactionTracker in on_transaction_status

* do_wait

bridges/relays/utils/src/lib.rs

@@ -20,6 +20,7 @@ pub use bp_runtime::HeaderId;
 pub use error::Error;
 pub use relay_loop::{relay_loop, relay_metrics};
 
+use async_trait::async_trait;
 use backoff::{backoff::Backoff, ExponentialBackoff};
 use futures::future::FutureExt;
 use std::time::Duration;
@@ -119,6 +120,22 @@ pub trait MaybeConnectionError {
 	fn is_connection_error(&self) -> bool;
 }
 
+/// Final status of the tracked transaction.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum TrackedTransactionStatus {
+	/// Transaction has been lost.
+	Lost,
+	/// Transaction has been mined and finalized.
+	Finalized,
+}
+
+/// Transaction tracker.
+#[async_trait]
+pub trait TransactionTracker: Send {
+	/// Wait until transaction is either finalized or invalidated/lost.
+	async fn wait(self) -> TrackedTransactionStatus;
+}
+
 /// Stringified error that may be either connection-related or not.
 #[derive(Error, Debug)]
 pub enum StringifiedMaybeConnectionError {