Decouple the session validators from im-online

bin/node/runtime/src/lib.rs

@@ -830,6 +830,7 @@ impl<C> frame_system::offchain::SendTransactionTypes<C> for Runtime where
 impl pallet_im_online::Config for Runtime {
 	type AuthorityId = ImOnlineId;
 	type Event = Event;
+	type ValidatorSet = Historical;
 	type SessionDuration = SessionDuration;
 	type ReportUnresponsiveness = Offences;
 	type UnsignedPriority = ImOnlineUnsignedPriority;

frame/aura/Cargo.toml

@@ -20,6 +20,7 @@ sp-std = { version = "2.0.0", default-features = false, path = "../../primitives
 serde = { version = "1.0.101", optional = true }
 pallet-session = { version = "2.0.0", default-features = false, path = "../session" }
 sp-runtime = { version = "2.0.0", default-features = false, path = "../../primitives/runtime" }
+sp-session = { version = "2.0.0", default-features = false, path = "../../primitives/session" }
 frame-support = { version = "2.0.0", default-features = false, path = "../support" }
 sp-consensus-aura = { version = "0.8.0", path = "../../primitives/consensus/aura", default-features = false }
 frame-system = { version = "2.0.0", default-features = false, path = "../system" }
@@ -41,6 +42,7 @@ std = [
 	"sp-std/std",
 	"serde",
 	"sp-runtime/std",
+	"sp-session/std",
 	"frame-support/std",
 	"sp-consensus-aura/std",
 	"frame-system/std",

frame/aura/src/lib.rs

@@ -46,7 +46,7 @@
 
 use sp_std::{result, prelude::*};
 use codec::{Encode, Decode};
-use frame_support::{Parameter, traits::{Get, FindAuthor}, ConsensusEngineId};
+use frame_support::{Parameter, traits::{Get, FindAuthor, OneSessionHandler}, ConsensusEngineId};
 use sp_runtime::{
 	RuntimeAppPublic,
 	traits::{SaturatedConversion, Saturating, Zero, Member, IsMember}, generic::DigestItem,
@@ -144,7 +144,7 @@ impl<T: Config> sp_runtime::BoundToRuntimeAppPublic for Pallet<T> {
 	type Public = T::AuthorityId;
 }
 
-impl<T: Config> pallet_session::OneSessionHandler<T::AccountId> for Pallet<T> {
+impl<T: Config> OneSessionHandler<T::AccountId> for Module<T> {
 	type Key = T::AuthorityId;
 
 	fn on_genesis_session<'a, I: 'a>(validators: I)

frame/authority-discovery/Cargo.toml

@@ -20,6 +20,7 @@ sp-std = { version = "2.0.0", default-features = false, path = "../../primitives
 serde = { version = "1.0.101", optional = true }
 pallet-session = { version = "2.0.0", features = ["historical" ], path = "../session", default-features = false }
 sp-runtime = { version = "2.0.0", default-features = false, path = "../../primitives/runtime" }
+sp-session = { version = "2.0.0", default-features = false, path = "../../primitives/session" }
 frame-support = { version = "2.0.0", default-features = false, path = "../support" }
 frame-system = { version = "2.0.0", default-features = false, path = "../system" }
 
@@ -38,6 +39,7 @@ std = [
 	"serde",
 	"pallet-session/std",
 	"sp-runtime/std",
+	"sp-session/std",
 	"frame-support/std",
 	"frame-system/std",
 ]

frame/authority-discovery/src/lib.rs

@@ -24,7 +24,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use sp_std::prelude::*;
-use frame_support::{decl_module, decl_storage};
+use frame_support::{decl_module, decl_storage, traits::OneSessionHandler};
 use sp_authority_discovery::AuthorityId;
 
 /// The module's config trait.
@@ -85,7 +85,7 @@ impl<T: Config> sp_runtime::BoundToRuntimeAppPublic for Module<T> {
 	type Public = AuthorityId;
 }
 
-impl<T: Config> pallet_session::OneSessionHandler<T::AccountId> for Module<T> {
+impl<T: Config> OneSessionHandler<T::AccountId> for Module<T> {
 	type Key = AuthorityId;
 
 	fn on_genesis_session<'a, I: 'a>(authorities: I)
@@ -265,7 +265,7 @@ mod tests {
 		let mut externalities = TestExternalities::new(t);
 
 		externalities.execute_with(|| {
-			use pallet_session::OneSessionHandler;
+			use frame_support::traits::OneSessionHandler;
 
 			AuthorityDiscovery::on_genesis_session(
 				first_authorities.iter().map(|id| (id, id.clone()))

frame/babe/src/lib.rs

@@ -25,7 +25,7 @@ use codec::{Decode, Encode};
 use frame_support::{
 	decl_error, decl_module, decl_storage,
 	dispatch::DispatchResultWithPostInfo,
-	traits::{FindAuthor, Get, KeyOwnerProofSystem, Randomness as RandomnessT},
+	traits::{FindAuthor, Get, KeyOwnerProofSystem, OneSessionHandler, Randomness as RandomnessT},
 	weights::{Pays, Weight},
 	Parameter,
 };
@@ -769,7 +769,7 @@ impl<T: Config> sp_runtime::BoundToRuntimeAppPublic for Module<T> {
 	type Public = AuthorityId;
 }
 
-impl<T: Config> pallet_session::OneSessionHandler<T::AccountId> for Module<T> {
+impl<T: Config> OneSessionHandler<T::AccountId> for Module<T> {
 	type Key = AuthorityId;
 
 	fn on_genesis_session<'a, I: 'a>(validators: I)

frame/grandpa/src/lib.rs

@@ -41,7 +41,7 @@ use fg_primitives::{
 };
 use frame_support::{
 	decl_error, decl_event, decl_module, decl_storage, dispatch::DispatchResultWithPostInfo,
-	storage, traits::KeyOwnerProofSystem, weights::{Pays, Weight}, Parameter,
+	storage, traits::{OneSessionHandler, KeyOwnerProofSystem}, weights::{Pays, Weight}, Parameter,
 };
 use frame_system::{ensure_none, ensure_root, ensure_signed};
 use sp_runtime::{
@@ -587,7 +587,7 @@ impl<T: Config> sp_runtime::BoundToRuntimeAppPublic for Module<T> {
 	type Public = AuthorityId;
 }
 
-impl<T: Config> pallet_session::OneSessionHandler<T::AccountId> for Module<T>
+impl<T: Config> OneSessionHandler<T::AccountId> for Module<T>
 	where T: pallet_session::Config
 {
 	type Key = AuthorityId;

frame/grandpa/src/tests.rs

@@ -25,11 +25,10 @@ use codec::{Decode, Encode};
 use fg_primitives::ScheduledChange;
 use frame_support::{
 	assert_err, assert_ok,
-	traits::{Currency, OnFinalize},
+	traits::{Currency, OnFinalize, OneSessionHandler},
 	weights::{GetDispatchInfo, Pays},
 };
 use frame_system::{EventRecord, Phase};
-use pallet_session::OneSessionHandler;
 use sp_core::H256;
 use sp_keyring::Ed25519Keyring;
 use sp_runtime::testing::Digest;

frame/im-online/Cargo.toml

@@ -19,28 +19,31 @@ codec = { package = "parity-scale-codec", version = "2.0.0", default-features =
 sp-core = { version = "2.0.0", default-features = false, path = "../../primitives/core" }
 sp-std = { version = "2.0.0", default-features = false, path = "../../primitives/std" }
 serde = { version = "1.0.101", optional = true }
-pallet-session = { version = "2.0.0", default-features = false, path = "../session" }
 sp-io = { version = "2.0.0", default-features = false, path = "../../primitives/io" }
 sp-runtime = { version = "2.0.0", default-features = false, path = "../../primitives/runtime" }
 sp-staking = { version = "2.0.0", default-features = false, path = "../../primitives/staking" }
+sp-session = { version = "2.0.0", default-features = false, path = "../../primitives/session" }
 frame-support = { version = "2.0.0", default-features = false, path = "../support" }
 frame-system = { version = "2.0.0", default-features = false, path = "../system" }
 
 frame-benchmarking = { version = "2.0.0", default-features = false, path = "../benchmarking", optional = true }
 
+[dev-dependencies]
+pallet-session = { version = "2.0.0", path = "../session" }
+
 [features]
-default = ["std", "pallet-session/historical"]
+default = ["std"]
 std = [
 	"sp-application-crypto/std",
 	"pallet-authorship/std",
 	"codec/std",
 	"sp-core/std",
 	"sp-std/std",
 	"serde",
-	"pallet-session/std",
 	"sp-io/std",
 	"sp-runtime/std",
 	"sp-staking/std",
+	"sp-session/std",
 	"frame-support/std",
 	"frame-system/std",
 ]