Events to track extrinsic success (#640)

* Initial draft

* Fixes

* Extrinsic success events

substrate/substrate/runtime/system/src/lib.rs

@@ -83,7 +83,7 @@ pub trait Trait: Eq + Clone {
 		Hash = Self::Hash,
 		Digest = Self::Digest
 	>;
-	type Event: Parameter + Member;
+	type Event: Parameter + Member + From<Event>;
 }
 
 decl_module! {
@@ -110,6 +110,20 @@ pub struct EventRecord<E: Parameter + Member> {
 	pub event: E,
 }
 
+/// Event for the system module. 
+#[derive(Encode, Decode, PartialEq, Eq, Clone)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize, Debug))]
+pub enum Event {
+	/// An extrinsic completed successfully.
+	ExtrinsicSuccess,
+	/// An extrinsic failed.
+	ExtrinsicFailed,
+}
+
+impl From<Event> for () {
+	fn from(_: Event) -> () { () }
+}
+
 decl_storage! {
 	trait Store for Module<T: Trait> as System {
 
@@ -230,7 +244,11 @@ impl<T: Trait> Module<T> {
 	}
 
 	/// To be called immediately after an extrinsic has been applied.
-	pub fn note_applied_extrinsic() {
+	pub fn note_applied_extrinsic(r: &Result<(), &'static str>) {
+		Self::deposit_event(match r {
+			Ok(_) => Event::ExtrinsicSuccess,
+			Err(_) => Event::ExtrinsicFailed,
+		}.into());
 		<ExtrinsicIndex<T>>::put(<ExtrinsicIndex<T>>::get().unwrap_or_default() + 1u32);
 	}
 
@@ -301,6 +319,15 @@ mod tests {
 		type Event = u16;
 	}
 
+	impl From<Event> for u16 {
+		fn from(e: Event) -> u16 {
+			match e { 
+				Event::ExtrinsicSuccess => 100,
+				Event::ExtrinsicFailed => 101,
+			}
+		}
+	}
+
 	type System = Module<Test>;
 
 	fn new_test_ext() -> runtime_io::TestExternalities<KeccakHasher> {
@@ -318,15 +345,15 @@ mod tests {
 
 			System::initialise(&2, &[0u8; 32].into(), &[0u8; 32].into());
 			System::deposit_event(42u16);
-			System::note_applied_extrinsic();
-			System::deposit_event(69u16);
-			System::note_applied_extrinsic();
+			System::note_applied_extrinsic(&Ok(()));
+			System::note_applied_extrinsic(&Err(""));
 			System::note_finished_extrinsics();
 			System::deposit_event(3u16);
 			System::finalise();
 			assert_eq!(System::events(), vec![
 				EventRecord { phase: Phase::ApplyExtrinsic(0), event: 42u16 },
-				EventRecord { phase: Phase::ApplyExtrinsic(1), event: 69u16 },
+				EventRecord { phase: Phase::ApplyExtrinsic(0), event: 100u16 },
+				EventRecord { phase: Phase::ApplyExtrinsic(1), event: 101u16 },
 				EventRecord { phase: Phase::Finalization, event: 3u16 }
 			]);
 		});