Aggregate all liquidity restrictions in a single place (#1921)

* Clean up session key rotation * Fix build * Bump version * Introduce feature to balances. * Move staking locking logic over to central point * ^^^ rest * First part of assimilation * More assimilation * More assimilation * Fix most tests * Fix build * Move Balances to new locking system * :q! * Bump runtime version * Build runtime * Convenience function * Test fix. * Whitespace * Improve type legibility. * Fix comment. * More tests. * More tests. * Bump version * Caps * Whitespace * Whitespace * Remove unneeded function.
2026-06-11 07:11:06 +00:00 · 2019-03-06 12:46:17 +01:00
parent 46541ec73c
commit ccc11974ee
62 changed files with 795 additions and 346 deletions
@@ -212,6 +212,11 @@ name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"

+[[package]]
+name = "bitmask"
+version = "0.5.0"
+source = "git+https://github.com/paritytech/bitmask#c2d8d196e30b018d1385be8357fdca61b978facf"
+
 [[package]]
 name = "blake2"
 version = "0.8.0"
@@ -3052,6 +3057,7 @@ dependencies = [
 "hex-literal 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec-derive 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "parking_lot 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.87 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-io 0.1.0",
@@ -3343,6 +3349,7 @@ dependencies = [
 name = "srml-support"
 version = "0.1.0"
 dependencies = [
+ "bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)",
 "hex-literal 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "once_cell 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -3415,7 +3422,6 @@ dependencies = [
 "sr-io 0.1.0",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
- "srml-consensus 0.1.0",
 "srml-support 0.1.0",
 "srml-system 0.1.0",
 "substrate-inherents 0.1.0",
@@ -4608,7 +4614,7 @@ name = "twox-hash"
 version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

 [[package]]
@@ -4954,6 +4960,7 @@ dependencies = [
 "checksum bigint 4.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ebecac13b3c745150d7b6c3ea7572d372f09d627c2077e893bf26c5c7f70d282"
 "checksum bindgen 0.43.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6d52d263eacd15d26cbcf215d254b410bd58212aaa2d3c453a04b2d3b3adcf41"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)" = "<none>"
 "checksum blake2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "91721a6330935673395a0607df4d49a9cb90ae12d259f1b3e0a3f6e1d486872e"
 "checksum blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"
 "checksum block-buffer 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1339a1042f5d9f295737ad4d9a6ab6bf81c84a933dba110b9200cd6d1448b814"
@@ -189,7 +189,6 @@ dependencies = [
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "primitive-types 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "rustc-hex 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.79 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-std 0.1.0",
 ]

@@ -8,7 +8,7 @@ edition = "2018"
 rstd = { package = "sr-std", path = "../sr-std", default-features = false }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 rustc-hex = { version = "2.0", default-features = false }
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 twox-hash = { version = "1.1.0", optional = true }
 byteorder = { version = "1.1", default-features = false }
@@ -46,7 +46,7 @@ std = [
 	"hash256-std-hasher/std",
 	"hash-db/std",
 	"rstd/std",
-	"serde/std",
+	"serde",
 	"rustc-hex/std",
 	"twox-hash",
 	"blake2-rfc",
@@ -5,5 +5,5 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = "1.0"
 serde_json = "1.0"
@@ -17,19 +17,29 @@
 #[doc(hidden)]
 pub use parity_codec as codec;
 // re-export hashing functions.
-pub use primitives::{blake2_256, twox_128, twox_256, ed25519, Blake2Hasher, sr25519};
+pub use primitives::{
+	blake2_256, twox_128, twox_256, ed25519, Blake2Hasher, sr25519
+};
 pub use tiny_keccak::keccak256 as keccak_256;
 // Switch to this after PoC-3
 // pub use primitives::BlakeHasher;
-pub use substrate_state_machine::{Externalities, TestExternalities};
+pub use substrate_state_machine::{Externalities, BasicExternalities, TestExternalities};

 use environmental::{environmental, thread_local_impl};
-use primitives::hexdisplay::HexDisplay;
-use primitives::H256;
+use primitives::{hexdisplay::HexDisplay, H256};
 use hash_db::Hasher;

+#[cfg(feature = "std")]
+use std::collections::HashMap;
+
 environmental!(ext: trait Externalities<Blake2Hasher>);

+/// A set of key value pairs for storage.
+pub type StorageOverlay = HashMap<Vec<u8>, Vec<u8>>;
+
+/// A set of key value pairs for children storage;
+pub type ChildrenStorageOverlay = HashMap<Vec<u8>, StorageOverlay>;
+
 /// Get `key` from storage and return a `Vec`, empty if there's a problem.
 pub fn storage(key: &[u8]) -> Option<Vec<u8>> {
 	ext::with(|ext| ext.storage(key).map(|s| s.to_vec()))
@@ -196,7 +206,7 @@ pub fn sr25519_verify<P: AsRef<[u8]>>(sig: &[u8; 64], msg: &[u8], pubkey: P) ->

 /// Verify and recover a SECP256k1 ECDSA signature.
 /// - `sig` is passed in RSV format. V should be either 0/1 or 27/28.
-/// - returns `Err` if the signatue is bad, otherwise the 64-byte pubkey (doesn't include the 0x04 prefix).
+/// - returns `Err` if the signature is bad, otherwise the 64-byte pubkey (doesn't include the 0x04 prefix).
 pub fn secp256k1_ecdsa_recover(sig: &[u8; 65], msg: &[u8; 32]) -> Result<[u8; 64], EcdsaVerifyError> {
 	let rs = secp256k1::Signature::parse_slice(&sig[0..64]).map_err(|_| EcdsaVerifyError::BadRS)?;
 	let v = secp256k1::RecoveryId::parse(if sig[64] > 26 { sig[64] - 27 } else { sig[64] } as u8).map_err(|_| EcdsaVerifyError::BadV)?;
@@ -213,6 +223,17 @@ pub fn with_externalities<R, F: FnOnce() -> R>(ext: &mut Externalities<Blake2Has
 	ext::using(ext, f)
 }

+/// Execute the given closure with global functions available whose functionality routes into
+/// externalities that draw from and populate `storage`. Forwards the value that the closure returns.
+pub fn with_storage<R, F: FnOnce() -> R>(storage: &mut StorageOverlay, f: F) -> R {
+	let mut alt_storage = Default::default();
+	rstd::mem::swap(&mut alt_storage, storage);
+	let mut ext: BasicExternalities = alt_storage.into();
+	let r = ext::using(&mut ext, f);
+	*storage = ext.into();
+	r
+}
+
 /// Trait for things which can be printed.
 pub trait Printable {
 	fn print(self);
@@ -248,7 +269,7 @@ mod std_tests {

 	#[test]
 	fn storage_works() {
-		let mut t = TestExternalities::<Blake2Hasher>::default();
+		let mut t = BasicExternalities::default();
 		assert!(with_externalities(&mut t, || {
 			assert_eq!(storage(b"hello"), None);
 			set_storage(b"hello", b"world");
@@ -258,7 +279,7 @@ mod std_tests {
 			true
 		}));

-		t = TestExternalities::new(map![b"foo".to_vec() => b"bar".to_vec()]);
+		t = BasicExternalities::new(map![b"foo".to_vec() => b"bar".to_vec()]);

 		assert!(!with_externalities(&mut t, || {
 			assert_eq!(storage(b"hello"), None);
@@ -269,7 +290,7 @@ mod std_tests {

 	#[test]
 	fn read_storage_works() {
-		let mut t = TestExternalities::<Blake2Hasher>::new(map![
+		let mut t = BasicExternalities::new(map![
 			b":test".to_vec() => b"\x0b\0\0\0Hello world".to_vec()
 		]);

@@ -285,7 +306,7 @@ mod std_tests {

 	#[test]
 	fn clear_prefix_works() {
-		let mut t = TestExternalities::<Blake2Hasher>::new(map![
+		let mut t = BasicExternalities::new(map![
 			b":a".to_vec() => b"\x0b\0\0\0Hello world".to_vec(),
 			b":abcd".to_vec() => b"\x0b\0\0\0Hello world".to_vec(),
 			b":abc".to_vec() => b"\x0b\0\0\0Hello world".to_vec(),
@@ -13,7 +13,7 @@ parity-codec = { version = "3.1", default-features = false, features = ["derive"
 substrate-primitives = { path = "../primitives", default-features = false }
 rstd = { package = "sr-std", path = "../sr-std", default-features = false }
 runtime_io = { package = "sr-io", path = "../sr-io", default-features = false }
-log = {version = "0.4", optional = true }
+log = { version = "0.4", optional = true }

 [dev-dependencies]
 serde_json = "1.0"
@@ -27,7 +27,7 @@ pub use parity_codec as codec;
 pub use serde_derive;

 #[cfg(feature = "std")]
-use std::collections::HashMap;
+pub use runtime_io::{StorageOverlay, ChildrenStorageOverlay};

 use rstd::prelude::*;
 use substrate_primitives::hash::{H256, H512};
@@ -87,17 +87,9 @@ pub use serde::{Serialize, de::DeserializeOwned};
 #[cfg(feature = "std")]
 use serde_derive::{Serialize, Deserialize};

-/// A set of key value pairs for storage.
-#[cfg(feature = "std")]
-pub type StorageOverlay = HashMap<Vec<u8>, Vec<u8>>;
-
-/// A set of key value pairs for children storage;
-#[cfg(feature = "std")]
-pub type ChildrenStorageOverlay = HashMap<Vec<u8>, StorageOverlay>;
-
 /// Complex storage builder stuff.
 #[cfg(feature = "std")]
-pub trait BuildStorage {
+pub trait BuildStorage: Sized {
 	/// Hash given slice.
 	///
 	/// Default to xx128 hashing.
@@ -107,7 +99,21 @@ pub trait BuildStorage {
 		r
 	}
 	/// Build the storage out of this builder.
-	fn build_storage(self) -> Result<(StorageOverlay, ChildrenStorageOverlay), String>;
+	fn build_storage(self) -> Result<(StorageOverlay, ChildrenStorageOverlay), String> {
+		let mut storage = Default::default();
+		let mut child_storage = Default::default();
+		self.assimilate_storage(&mut storage, &mut child_storage)?;
+		Ok((storage, child_storage))
+	}
+	/// Assimilate the storage for this module into pre-existing overlays.
+	fn assimilate_storage(self, storage: &mut StorageOverlay, child_storage: &mut ChildrenStorageOverlay) -> Result<(), String> {
+		let (s, cs) = self.build_storage()?;
+		storage.extend(s);
+		for (other_child_key, other_child_map) in cs {
+			child_storage.entry(other_child_key).or_default().extend(other_child_map);
+		}
+		Ok(())
+	}
 }

 #[cfg(feature = "std")]
@@ -115,6 +121,10 @@ impl BuildStorage for StorageOverlay {
 	fn build_storage(self) -> Result<(StorageOverlay, ChildrenStorageOverlay), String> {
 		Ok((self, Default::default()))
 	}
+	fn assimilate_storage(self, storage: &mut StorageOverlay, _child_storage: &mut ChildrenStorageOverlay) -> Result<(), String> {
+		storage.extend(self);
+		Ok(())
+	}
 }

 /// Permill is parts-per-million (i.e. after multiplying by this, divide by 1000000).
@@ -411,6 +421,14 @@ macro_rules! impl_outer_config {
 		}
 		#[cfg(any(feature = "std", test))]
 		impl $crate::BuildStorage for $main {
+			fn assimilate_storage(self, top: &mut $crate::StorageOverlay, children: &mut $crate::ChildrenStorageOverlay) -> ::std::result::Result<(), String> {
+				$(
+					if let Some(extra) = self.$snake {
+						extra.assimilate_storage(top, children)?;
+					}
+				)*
+				Ok(())
+			}
 			fn build_storage(self) -> ::std::result::Result<($crate::StorageOverlay, $crate::ChildrenStorageOverlay), String> {
 				let mut top = $crate::StorageOverlay::new();
 				let mut children = $crate::ChildrenStorageOverlay::new();
@@ -23,8 +23,7 @@ use runtime_io;
 #[cfg(feature = "std")] use serde::{Serialize, de::DeserializeOwned};
 #[cfg(feature = "std")]
 use serde_derive::{Serialize, Deserialize};
-use substrate_primitives;
-use substrate_primitives::Blake2Hasher;
+use substrate_primitives::{self, Hasher, Blake2Hasher};
 use crate::codec::{Codec, Encode, HasCompact};
 pub use integer_sqrt::IntegerSquareRoot;
 pub use num_traits::{
@@ -84,6 +83,8 @@ pub trait StaticLookup {
 	type Target;
 	/// Attempt a lookup.
 	fn lookup(s: Self::Source) -> result::Result<Self::Target, &'static str>;
+	/// Convert from Target back to Source.
+	fn unlookup(t: Self::Target) -> Self::Source;
 }

 /// A lookup implementation returning the input value.
@@ -93,6 +94,7 @@ impl<T: Codec + Clone + PartialEq + MaybeDebug> StaticLookup for IdentityLookup<
 	type Source = T;
 	type Target = T;
 	fn lookup(x: T) -> result::Result<T, &'static str> { Ok(x) }
+	fn unlookup(x: T) -> T { x }
 }
 impl<T> Lookup for IdentityLookup<T> {
 	type Source = T;
@@ -184,7 +186,7 @@ pub trait SimpleArithmetic:
 	CheckedMul +
 	CheckedDiv +
 	Saturating +
-	PartialOrd<Self> + Ord +
+	PartialOrd<Self> + Ord + Bounded +
 	HasCompact
 {}
 impl<T:
@@ -202,7 +204,7 @@ impl<T:
 	CheckedMul +
 	CheckedDiv +
 	Saturating +
-	PartialOrd<Self> + Ord +
+	PartialOrd<Self> + Ord + Bounded +
 	HasCompact
 > SimpleArithmetic for T {}

@@ -298,7 +300,10 @@ tuple_impl!(A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W,
 pub trait Hash: 'static + MaybeSerializeDebug + Clone + Eq + PartialEq {	// Stupid bug in the Rust compiler believes derived
 																	// traits must be fulfilled by all type parameters.
 	/// The hash type produced.
-	type Output: Member + MaybeSerializeDebug + AsRef<[u8]> + AsMut<[u8]>;
+	type Output: Member + MaybeSerializeDebug + rstd::hash::Hash + AsRef<[u8]> + AsMut<[u8]> + Copy + Default;
+
+	/// The associated hash_db Hasher type.
+	type Hasher: Hasher<Out=Self::Output>;

 	/// Produce the hash of some byte-slice.
 	fn hash(s: &[u8]) -> Self::Output;
@@ -338,6 +343,7 @@ pub struct BlakeTwo256;

 impl Hash for BlakeTwo256 {
 	type Output = substrate_primitives::H256;
+	type Hasher = Blake2Hasher;
 	fn hash(s: &[u8]) -> Self::Output {
 		runtime_io::blake2_256(s).into()
 	}
@@ -480,6 +486,7 @@ pub trait MaybeHash {}
 #[cfg(not(feature = "std"))]
 impl<T> MaybeHash for T {}

+
 /// A type that can be used in runtime structures.
 pub trait Member: Send + Sync + Sized + MaybeDebug + Eq + PartialEq + Clone + 'static {}
 impl<T: Send + Sync + Sized + MaybeDebug + Eq + PartialEq + Clone + 'static> Member for T {}
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 impl-serde = { version = "0.1", optional = true }
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 rstd = { package = "sr-std", path = "../sr-std", default-features = false }
@@ -16,7 +16,7 @@ runtime_primitives = { package = "sr-primitives", path = "../sr-primitives", def
 default = ["std"]
 std = [
 	"impl-serde",
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"parity-codec/std",
 	"rstd/std",
@@ -0,0 +1,183 @@
+// Copyright 2017-2018 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Basic implementation for Externalities.
+
+use std::collections::HashMap;
+use std::iter::FromIterator;
+use hash_db::Hasher;
+use heapsize::HeapSizeOf;
+use trie::trie_root;
+use primitives::storage::well_known_keys::{CHANGES_TRIE_CONFIG, CODE, HEAP_PAGES};
+use parity_codec::Encode;
+use super::{Externalities, OverlayedChanges};
+
+/// Simple HashMap-based Externalities impl.
+pub struct BasicExternalities {
+	inner: HashMap<Vec<u8>, Vec<u8>>,
+	changes: OverlayedChanges,
+	code: Option<Vec<u8>>,
+}
+
+impl BasicExternalities {
+	/// Create a new instance of `BasicExternalities`
+	pub fn new(inner: HashMap<Vec<u8>, Vec<u8>>) -> Self {
+		Self::new_with_code(&[], inner)
+	}
+
+	/// Create a new instance of `BasicExternalities`
+	pub fn new_with_code(code: &[u8], mut inner: HashMap<Vec<u8>, Vec<u8>>) -> Self {
+		let mut overlay = OverlayedChanges::default();
+		super::set_changes_trie_config(
+			&mut overlay,
+			inner.get(&CHANGES_TRIE_CONFIG.to_vec()).cloned(),
+			false,
+		).expect("changes trie configuration is correct in test env; qed");
+
+		inner.insert(HEAP_PAGES.to_vec(), 8u64.encode());
+
+		BasicExternalities {
+			inner,
+			changes: overlay,
+			code: Some(code.to_vec()),
+		}
+	}
+
+	/// Insert key/value
+	pub fn insert(&mut self, k: Vec<u8>, v: Vec<u8>) -> Option<Vec<u8>> {
+		self.inner.insert(k, v)
+	}
+}
+
+impl ::std::fmt::Debug for BasicExternalities {
+	fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+		write!(f, "{:?}", self.inner)
+	}
+}
+
+impl PartialEq for BasicExternalities {
+	fn eq(&self, other: &BasicExternalities) -> bool {
+		self.inner.eq(&other.inner)
+	}
+}
+
+impl FromIterator<(Vec<u8>, Vec<u8>)> for BasicExternalities {
+	fn from_iter<I: IntoIterator<Item=(Vec<u8>, Vec<u8>)>>(iter: I) -> Self {
+		let mut t = Self::new(Default::default());
+		t.inner.extend(iter);
+		t
+	}
+}
+
+impl Default for BasicExternalities {
+	fn default() -> Self { Self::new(Default::default()) }
+}
+
+impl From<BasicExternalities> for HashMap<Vec<u8>, Vec<u8>> {
+	fn from(tex: BasicExternalities) -> Self {
+		tex.inner.into()
+	}
+}
+
+impl From< HashMap<Vec<u8>, Vec<u8>> > for BasicExternalities {
+	fn from(hashmap: HashMap<Vec<u8>, Vec<u8>>) -> Self {
+		BasicExternalities {
+			inner: hashmap,
+			changes: Default::default(),
+			code: None,
+		}
+	}
+}
+
+impl<H: Hasher> Externalities<H> for BasicExternalities where H::Out: Ord + HeapSizeOf {
+	fn storage(&self, key: &[u8]) -> Option<Vec<u8>> {
+		match key {
+			CODE => self.code.clone(),
+			_ => self.inner.get(key).cloned(),
+		}
+	}
+
+	fn child_storage(&self, _storage_key: &[u8], _key: &[u8]) -> Option<Vec<u8>> {
+		None
+	}
+
+	fn place_storage(&mut self, key: Vec<u8>, maybe_value: Option<Vec<u8>>) {
+		self.changes.set_storage(key.clone(), maybe_value.clone());
+		match key.as_ref() {
+			CODE => self.code = maybe_value,
+			_ => {
+				match maybe_value {
+					Some(value) => { self.inner.insert(key, value); }
+					None => { self.inner.remove(&key); }
+				}
+			}
+		}
+	}
+
+	fn place_child_storage(&mut self, _storage_key: Vec<u8>, _key: Vec<u8>, _value: Option<Vec<u8>>) -> bool {
+		false
+	}
+
+	fn kill_child_storage(&mut self, _storage_key: &[u8]) { }
+
+	fn clear_prefix(&mut self, prefix: &[u8]) {
+		self.changes.clear_prefix(prefix);
+		self.inner.retain(|key, _| !key.starts_with(prefix));
+	}
+
+	fn chain_id(&self) -> u64 { 42 }
+
+	fn storage_root(&mut self) -> H::Out {
+		trie_root::<H, _, _, _>(self.inner.clone())
+	}
+
+	fn child_storage_root(&mut self, _storage_key: &[u8]) -> Option<Vec<u8>> {
+		None
+	}
+
+	fn storage_changes_root(&mut self, _parent: H::Out, _parent_num: u64) -> Option<H::Out> {
+		None
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use primitives::{Blake2Hasher, H256};
+	use hex_literal::{hex, hex_impl};
+
+	#[test]
+	fn commit_should_work() {
+		let mut ext = BasicExternalities::default();
+		let ext = &mut ext as &mut Externalities<Blake2Hasher>;
+		ext.set_storage(b"doe".to_vec(), b"reindeer".to_vec());
+		ext.set_storage(b"dog".to_vec(), b"puppy".to_vec());
+		ext.set_storage(b"dogglesworth".to_vec(), b"cat".to_vec());
+		const ROOT: [u8; 32] = hex!("0b33ed94e74e0f8e92a55923bece1ed02d16cf424e124613ddebc53ac3eeeabe");
+		assert_eq!(ext.storage_root(), H256::from(ROOT));
+	}
+
+	#[test]
+	fn set_and_retrieve_code() {
+		let mut ext = BasicExternalities::default();
+		let ext = &mut ext as &mut Externalities<Blake2Hasher>;
+
+		let code = vec![1, 2, 3];
+		ext.set_storage(CODE.to_vec(), code.clone());
+
+		assert_eq!(&ext.storage(CODE).unwrap(), &code);
+	}
+}
@@ -29,6 +29,7 @@ pub mod backend;
 mod changes_trie;
 mod ext;
 mod testing;
+mod basic;
 mod overlayed_changes;
 mod proving_backend;
 mod trie_backend;
@@ -37,6 +38,7 @@ mod trie_backend_essence;
 use overlayed_changes::OverlayedChangeSet;
 pub use trie::{TrieMut, TrieDBMut, DBValue, MemoryDB};
 pub use testing::TestExternalities;
+pub use basic::BasicExternalities;
 pub use ext::Ext;
 pub use backend::Backend;
 pub use changes_trie::{
@@ -625,7 +627,7 @@ where
 /// differs from previous OR config decode has failed.
 pub(crate) fn set_changes_trie_config(overlay: &mut OverlayedChanges, config: Option<Vec<u8>>, final_check: bool) -> Result<(), Box<Error>> {
 	let config = match config {
-		Some(v) => Some(changes_trie::Configuration::decode(&mut &v[..])
+		Some(v) => Some(Decode::decode(&mut &v[..])
 			.ok_or_else(|| Box::new("Failed to decode changes trie configuration".to_owned()) as Box<Error>)?),
 		None => None,
 	};
@@ -44,6 +44,11 @@ name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"

+[[package]]
+name = "bitmask"
+version = "0.5.0"
+source = "git+https://github.com/paritytech/bitmask#c2d8d196e30b018d1385be8357fdca61b978facf"
+
 [[package]]
 name = "blake2-rfc"
 version = "0.2.18"
@@ -1221,6 +1226,7 @@ dependencies = [
 name = "srml-support"
 version = "0.1.0"
 dependencies = [
+ "bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)",
 "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "once_cell 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1863,6 +1869,7 @@ dependencies = [
 "checksum backtrace-sys 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)" = "c66d56ac8dabd07f6aacdaf633f4b8262f5b3601a810a0dcddffd5c22c69daa0"
 "checksum base58 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5024ee8015f02155eee35c711107ddd9a9bf3cb689cf2a9089c97e79b6e1ae83"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)" = "<none>"
 "checksum blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"
 "checksum block-buffer 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1339a1042f5d9f295737ad4d9a6ab6bf81c84a933dba110b9200cd6d1448b814"
 "checksum block-buffer 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "49665c62e0e700857531fa5d3763e91b539ff1abeebd56808d378b495870d60d"
@@ -72,7 +72,6 @@ impl Decode for NodeHeader {

 			BRANCH_NODE_NO_VALUE => NodeHeader::Branch(false),		// 254
 			BRANCH_NODE_WITH_VALUE => NodeHeader::Branch(true),		// 255
-			_ => unreachable!(),
 		})
 	}
 }
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
@@ -47,7 +47,7 @@ std = [
 	"sudo/std",
 	"version/std",
 	"serde_derive",
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"consensus-aura/std",
 ]
@@ -158,8 +158,6 @@ impl balances::Trait for Runtime {
 	type OnFreeBalanceZero = ();
 	/// What to do if a new account is created.
 	type OnNewAccount = Indices;
-	/// Restrict whether an account can transfer funds. We don't place any further restrictions.
-	type EnsureAccountLiquid = ();
 	/// The uniquitous event type.
 	type Event = Event;
 }
@@ -50,6 +50,11 @@ name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"

+[[package]]
+name = "bitmask"
+version = "0.5.0"
+source = "git+https://github.com/paritytech/bitmask#c2d8d196e30b018d1385be8357fdca61b978facf"
+
 [[package]]
 name = "blake2-rfc"
 version = "0.2.18"
@@ -1276,6 +1281,7 @@ version = "0.1.0"
 dependencies = [
 "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec-derive 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.85 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
@@ -1401,6 +1407,7 @@ dependencies = [
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.85 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sr-io 0.1.0",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
 "srml-consensus 0.1.0",
@@ -1429,6 +1436,7 @@ dependencies = [
 name = "srml-support"
 version = "0.1.0"
 dependencies = [
+ "bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)",
 "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "once_cell 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1499,7 +1507,6 @@ dependencies = [
 "serde 1.0.85 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
- "srml-consensus 0.1.0",
 "srml-support 0.1.0",
 "srml-system 0.1.0",
 "substrate-inherents 0.1.0",
@@ -2079,6 +2086,7 @@ dependencies = [
 "checksum backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)" = "797c830ac25ccc92a7f8a7b9862bde440715531514594a6154e3d4a54dd769b6"
 "checksum base58 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5024ee8015f02155eee35c711107ddd9a9bf3cb689cf2a9089c97e79b6e1ae83"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)" = "<none>"
 "checksum blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"
 "checksum block-buffer 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1339a1042f5d9f295737ad4d9a6ab6bf81c84a933dba110b9200cd6d1448b814"
 "checksum block-buffer 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "49665c62e0e700857531fa5d3763e91b539ff1abeebd56808d378b495870d60d"
@@ -318,9 +318,9 @@ mod tests {
 			sudo: Some(Default::default()),
 			grandpa: Some(GrandpaConfig {
 				authorities: vec![ // set these so no GRANDPA events fire when session changes
-					(keyring::ed25519::Keyring::Alice.to_raw_public().into(), 1),
-					(keyring::ed25519::Keyring::Bob.to_raw_public().into(), 1),
 					(keyring::ed25519::Keyring::Charlie.to_raw_public().into(), 1),
+					(keyring::ed25519::Keyring::Bob.to_raw_public().into(), 1),
+					(keyring::ed25519::Keyring::Alice.to_raw_public().into(), 1),
 				],
 			}),
 			fees: Some(FeesConfig {
@@ -449,9 +449,9 @@ mod tests {

 		let mut digest = generic::Digest::<Log>::default();
 		digest.push(Log::from(::grandpa::RawLog::AuthoritiesChangeSignal(0, vec![
-			(Keyring::One.to_raw_public().into(), 1),
-			(Keyring::Two.to_raw_public().into(), 1),
-			([3u8; 32].into(), 1),
+			(Keyring::Charlie.to_raw_public().into(), 1),
+			(Keyring::Alice.to_raw_public().into(), 1),
+			(Keyring::Bob.to_raw_public().into(), 1),
 		])));
 		assert_eq!(Header::decode(&mut &block2.0[..]).unwrap().digest, digest);

@@ -592,9 +592,9 @@ mod tests {
 				EventRecord {
 					phase: Phase::Finalization,
 					event: Event::grandpa(::grandpa::RawEvent::NewAuthorities(vec![
-						(Keyring::One.to_raw_public().into(), 1),
-						(Keyring::Two.to_raw_public().into(), 1),
-						([3u8; 32].into(), 1),
+						(Keyring::Charlie.to_raw_public().into(), 1),
+						(Keyring::Alice.to_raw_public().into(), 1),
+						(Keyring::Bob.to_raw_public().into(), 1),
 					])),
 				},
 				EventRecord {
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
@@ -26,5 +26,5 @@ std = [
 	"rstd/std",
 	"runtime_primitives/std",
 	"serde_derive",
-	"serde/std",
+	"serde",
 ]
@@ -65,7 +65,7 @@ std = [
 	"fees/std",
 	"version/std",
 	"node-primitives/std",
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"client/std",
 	"consensus_aura/std",
@@ -60,8 +60,8 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 33,
-	impl_version: 33,
+	spec_version: 34,
+	impl_version: 34,
 	apis: RUNTIME_API_VERSIONS,
 };

@@ -101,9 +101,8 @@ impl indices::Trait for Runtime {

 impl balances::Trait for Runtime {
 	type Balance = Balance;
-	type OnFreeBalanceZero = (((Staking, Contract), Democracy), Session);
+	type OnFreeBalanceZero = ((Staking, Contract), Session);
 	type OnNewAccount = Indices;
-	type EnsureAccountLiquid = (Staking, Democracy);
 	type Event = Event;
 }

@@ -116,7 +115,7 @@ impl consensus::Trait for Runtime {
 	type Log = Log;
 	type SessionKey = SessionKey;

-	// the aura module handles offline-reports internally
+	// The Aura module handles offline-reports internally
 	// rather than using an explicit report system.
 	type InherentOfflineReport = ();
 }
@@ -44,6 +44,11 @@ name = "bitflags"
 version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"

+[[package]]
+name = "bitmask"
+version = "0.5.0"
+source = "git+https://github.com/paritytech/bitmask#c2d8d196e30b018d1385be8357fdca61b978facf"
+
 [[package]]
 name = "blake2-rfc"
 version = "0.2.18"
@@ -1300,7 +1305,7 @@ version = "0.1.0"
 dependencies = [
 "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec-derive 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
 "srml-session 0.1.0",
@@ -1513,6 +1518,7 @@ dependencies = [
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "safe-mix 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "serde 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
+ "sr-io 0.1.0",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
 "srml-consensus 0.1.0",
@@ -1541,6 +1547,7 @@ dependencies = [
 name = "srml-support"
 version = "0.1.0"
 dependencies = [
+ "bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)",
 "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "once_cell 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-codec 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1611,7 +1618,6 @@ dependencies = [
 "serde 1.0.81 (registry+https://github.com/rust-lang/crates.io-index)",
 "sr-primitives 0.1.0",
 "sr-std 0.1.0",
- "srml-consensus 0.1.0",
 "srml-support 0.1.0",
 "srml-system 0.1.0",
 "substrate-inherents 0.1.0",
@@ -2224,6 +2230,7 @@ dependencies = [
 "checksum backtrace-sys 0.1.24 (registry+https://github.com/rust-lang/crates.io-index)" = "c66d56ac8dabd07f6aacdaf633f4b8262f5b3601a810a0dcddffd5c22c69daa0"
 "checksum base58 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5024ee8015f02155eee35c711107ddd9a9bf3cb689cf2a9089c97e79b6e1ae83"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
+"checksum bitmask 0.5.0 (git+https://github.com/paritytech/bitmask)" = "<none>"
 "checksum blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "5d6d530bdd2d52966a6d03b7a964add7ae1a288d25214066fd4b600f0f796400"
 "checksum block-buffer 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1339a1042f5d9f295737ad4d9a6ab6bf81c84a933dba110b9200cd6d1448b814"
 "checksum block-buffer 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "49665c62e0e700857531fa5d3763e91b539ff1abeebd56808d378b495870d60d"
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 # Needed for various traits. In our case, `OnFinalise`.
 primitives = { package = "sr-primitives", path = "../../core/sr-primitives", default-features = false }
@@ -23,7 +23,7 @@ runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"primitives/std",
 	"srml-support/std",
@@ -7,7 +7,8 @@ edition = "2018"
 [dependencies]
 hex-literal = "0.1.0"
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
-serde = { version = "1.0", default-features = false }
+parity-codec-derive = { version = "3.1", default-features = false }
+serde = { version = "1.0", optional = true }
 inherents = { package = "substrate-inherents", path = "../../core/inherents", default-features = false }
 rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
 primitives = { package = "sr-primitives", path = "../../core/sr-primitives", default-features = false }
@@ -27,7 +28,7 @@ consensus = { package = "srml-consensus", path = "../consensus" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"rstd/std",
 	"srml-support/std",
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 substrate-keyring = { path = "../../core/keyring", optional = true }
@@ -22,7 +22,7 @@ substrate-primitives = { path = "../../core/primitives" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"substrate-keyring",
 	"parity-codec/std",
@@ -29,7 +29,8 @@ use rstd::{cmp, result};
 use parity_codec::{Codec, Encode, Decode};
 use srml_support::{StorageValue, StorageMap, Parameter, decl_event, decl_storage, decl_module, ensure};
 use srml_support::traits::{
-	UpdateBalanceOutcome, Currency, EnsureAccountLiquid, OnFreeBalanceZero, TransferAsset, WithdrawReason, ArithmeticType
+	UpdateBalanceOutcome, Currency, OnFreeBalanceZero, TransferAsset,
+	WithdrawReason, WithdrawReasons, ArithmeticType, LockIdentifier, LockableCurrency
 };
 use srml_support::dispatch::Result;
 use primitives::traits::{
@@ -53,9 +54,6 @@ pub trait Trait: system::Trait {
 	/// Handler for when a new account is created.
 	type OnNewAccount: OnNewAccount<Self::AccountId>;

-	/// A function that returns true iff a given account can transfer its funds to another account.
-	type EnsureAccountLiquid: EnsureAccountLiquid<Self::AccountId, Self::Balance>;
-
 	/// The overarching event type.
 	type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
 }
@@ -99,6 +97,15 @@ impl<Balance: SimpleArithmetic + Copy + As<u64>> VestingSchedule<Balance> {
 	}
 }

+#[derive(Encode, Decode, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "std", derive(Debug))]
+pub struct BalanceLock<Balance, BlockNumber> {
+	pub id: LockIdentifier,
+	pub amount: Balance,
+	pub until: BlockNumber,
+	pub reasons: WithdrawReasons,
+}
+
 decl_storage! {
 	trait Store for Module<T: Trait> as Balances {
 		/// The total amount of stake on the system.
@@ -160,6 +167,9 @@ decl_storage! {
 		/// `system::AccountNonce` is also deleted if `FreeBalance` is also zero (it also gets
 		/// collapsed to zero if it ever becomes less than `ExistentialDeposit`.
 		pub ReservedBalance get(reserved_balance): map T::AccountId => T::Balance;
+
+		/// Any liquidity locks on some account balances.
+		pub Locks get(locks): map T::AccountId => Vec<BalanceLock<T::Balance, T::BlockNumber>>;
 	}
 	add_extra_genesis {
 		config(balances): Vec<(T::AccountId, T::Balance)>;
@@ -285,16 +295,14 @@ impl<T: Trait> Module<T> {
 			None => return Err("got overflow after adding a fee to value"),
 		};

-		let vesting_balance = Self::vesting_balance(transactor);
 		let new_from_balance = match from_balance.checked_sub(&liability) {
 			None => return Err("balance too low to send value"),
-			Some(b) if b < vesting_balance => return Err("vesting balance too high to send value"),
 			Some(b) => b,
 		};
 		if would_create && value < Self::existential_deposit() {
 			return Err("value too low to create account");
 		}
-		T::EnsureAccountLiquid::ensure_account_can_withdraw(transactor, value, WithdrawReason::Transfer)?;
+		Self::ensure_account_can_withdraw(transactor, value, WithdrawReason::Transfer, new_from_balance)?;

 		// NOTE: total stake being stored in the same type means that this could never overflow
 		// but better to be safe than sorry.
@@ -313,7 +321,6 @@ impl<T: Trait> Module<T> {
 		Ok(())
 	}

-
 	/// Register a new account (with existential balance).
 	fn new_account(who: &T::AccountId, balance: T::Balance) {
 		T::OnNewAccount::on_new_account(&who);
@@ -329,6 +336,7 @@ impl<T: Trait> Module<T> {
 	fn on_free_too_low(who: &T::AccountId) {
 		Self::decrease_total_stake_by(Self::free_balance(who));
 		<FreeBalance<T>>::remove(who);
+		<Locks<T>>::remove(who);

 		T::OnFreeBalanceZero::on_free_balance_zero(who);

@@ -359,6 +367,35 @@ impl<T: Trait> Module<T> {
 			<TotalIssuance<T>>::put(v);
 		}
 	}
+
+	/// Returns `Ok` iff the account is able to make a withdrawal of the given amount
+	/// for the given reason.
+	/// 
+	/// `Err(...)` with the reason why not otherwise.
+	pub fn ensure_account_can_withdraw(
+		who: &T::AccountId,
+		_amount: T::Balance,
+		reason: WithdrawReason,
+		new_balance: T::Balance,
+	) -> Result {
+		match reason {
+			WithdrawReason::Reserve | WithdrawReason::Transfer if Self::vesting_balance(who) > new_balance =>
+				return Err("vesting balance too high to send value"),
+			_ => {}
+		}
+		let locks = Self::locks(who);
+		if locks.is_empty() {
+			return Ok(())
+		}
+		let now = <system::Module<T>>::block_number();
+		if Self::locks(who).into_iter()
+			.all(|l| now >= l.until || new_balance >= l.amount || !l.reasons.contains(reason))
+		{
+			Ok(())
+		} else {
+			Err("account liquidity restrictions prevent withdrawal")
+		}
+	}
 }

 impl<T: Trait> Currency<T::AccountId> for Module<T>
@@ -376,11 +413,11 @@ where
 	}

 	fn can_reserve(who: &T::AccountId, value: Self::Balance) -> bool {
-		if T::EnsureAccountLiquid::ensure_account_can_withdraw(who, value, WithdrawReason::Reserve).is_ok() {
-			Self::free_balance(who) >= value
-		} else {
-			false
-		}
+		Self::free_balance(who)
+			.checked_sub(&value)
+			.map_or(false, |new_balance|
+				Self::ensure_account_can_withdraw(who, value, WithdrawReason::Reserve, new_balance).is_ok()
+			)
 	}

 	fn total_issuance() -> Self::Balance {
@@ -429,9 +466,10 @@ where
 		if b < value {
 			return Err("not enough free funds")
 		}
-		T::EnsureAccountLiquid::ensure_account_can_withdraw(who, value, WithdrawReason::Reserve)?;
+		let new_balance = b - value;
+		Self::ensure_account_can_withdraw(who, value, WithdrawReason::Reserve, new_balance)?;
 		Self::set_reserved_balance(who, Self::reserved_balance(who) + value);
-		Self::set_free_balance(who, b - value);
+		Self::set_free_balance(who, new_balance);
 		Ok(())
 	}

@@ -479,6 +517,80 @@ where
 	}
 }

+impl<T: Trait> LockableCurrency<T::AccountId> for Module<T>
+where
+	T::Balance: MaybeSerializeDebug
+{
+	type Moment = T::BlockNumber;
+
+	fn set_lock(
+		id: LockIdentifier,
+		who: &T::AccountId,
+		amount: T::Balance,
+		until: T::BlockNumber,
+		reasons: WithdrawReasons,
+	) {
+		let now = <system::Module<T>>::block_number();
+		let mut new_lock = Some(BalanceLock { id, amount, until, reasons });
+		let mut locks = Self::locks(who).into_iter().filter_map(|l|
+			if l.id == id {
+				new_lock.take()
+			} else if l.until > now {
+				Some(l)
+			} else {
+				None
+			}).collect::<Vec<_>>();
+		if let Some(lock) = new_lock {
+			locks.push(lock)
+		}
+		<Locks<T>>::insert(who, locks);
+	}
+
+	fn extend_lock(
+		id: LockIdentifier,
+		who: &T::AccountId,
+		amount: T::Balance,
+		until: T::BlockNumber,
+		reasons: WithdrawReasons,
+	) {
+		let now = <system::Module<T>>::block_number();
+		let mut new_lock = Some(BalanceLock { id, amount, until, reasons });
+		let mut locks = Self::locks(who).into_iter().filter_map(|l|
+			if l.id == id {
+				new_lock.take().map(|nl| {
+					BalanceLock {
+						id: l.id,
+						amount: l.amount.max(nl.amount),
+						until: l.until.max(nl.until),
+						reasons: l.reasons | nl.reasons,
+					}
+				})
+			} else if l.until > now {
+				Some(l)
+			} else {
+				None
+			}).collect::<Vec<_>>();
+		if let Some(lock) = new_lock {
+			locks.push(lock)
+		}
+		<Locks<T>>::insert(who, locks);
+	}
+
+	fn remove_lock(
+		id: LockIdentifier,
+		who: &T::AccountId,
+	) {
+		let now = <system::Module<T>>::block_number();
+		let locks = Self::locks(who).into_iter().filter_map(|l|
+			if l.until > now && l.id != id {
+				Some(l)
+			} else {
+				None
+			}).collect::<Vec<_>>();
+		<Locks<T>>::insert(who, locks);
+	}
+}
+
 impl<T: Trait> TransferAsset<T::AccountId> for Module<T> {
 	type Amount = T::Balance;

@@ -487,10 +599,11 @@ impl<T: Trait> TransferAsset<T::AccountId> for Module<T> {
 	}

 	fn withdraw(who: &T::AccountId, value: T::Balance, reason: WithdrawReason) -> Result {
-		T::EnsureAccountLiquid::ensure_account_can_withdraw(who, value, reason)?;
 		let b = Self::free_balance(who);
 		ensure!(b >= value, "account has too few funds");
-		Self::set_free_balance(who, b - value);
+		let new_balance = b - value;
+		Self::ensure_account_can_withdraw(who, value, reason, new_balance)?;
+		Self::set_free_balance(who, new_balance);
 		Self::decrease_total_stake_by(value);
 		Ok(())
 	}
@@ -49,7 +49,6 @@ impl Trait for Runtime {
 	type Balance = u64;
 	type OnFreeBalanceZero = ();
 	type OnNewAccount = ();
-	type EnsureAccountLiquid = ();
 	type Event = ();
 }

@@ -21,7 +21,136 @@
 use super::*;
 use mock::{Balances, ExtBuilder, Runtime, System};
 use runtime_io::with_externalities;
-use srml_support::{assert_noop, assert_ok, assert_err};
+use srml_support::{
+	assert_noop, assert_ok, assert_err,
+	traits::{LockableCurrency, LockIdentifier, WithdrawReason, WithdrawReasons, Currency, TransferAsset}
+};
+
+const ID_1: LockIdentifier = *b"1       ";
+const ID_2: LockIdentifier = *b"2       ";
+const ID_3: LockIdentifier = *b"3       ";
+
+#[test]
+fn basic_locking_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		assert_eq!(Balances::free_balance(&1), 10);
+		Balances::set_lock(ID_1, &1, 9, u64::max_value(), WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 5), "account liquidity restrictions prevent withdrawal");
+	});
+}
+
+#[test]
+fn partial_locking_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 5, u64::max_value(), WithdrawReasons::all());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn lock_removal_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, u64::max_value(), u64::max_value(), WithdrawReasons::all());
+		Balances::remove_lock(ID_1, &1);
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn lock_replacement_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, u64::max_value(), u64::max_value(), WithdrawReasons::all());
+		Balances::set_lock(ID_1, &1, 5, u64::max_value(), WithdrawReasons::all());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn double_locking_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 5, u64::max_value(), WithdrawReasons::all());
+		Balances::set_lock(ID_2, &1, 5, u64::max_value(), WithdrawReasons::all());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn combination_locking_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, u64::max_value(), 0, WithdrawReasons::none());
+		Balances::set_lock(ID_2, &1, 0, u64::max_value(), WithdrawReasons::none());
+		Balances::set_lock(ID_3, &1, 0, 0, WithdrawReasons::all());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn lock_value_extension_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 5, u64::max_value(), WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		Balances::extend_lock(ID_1, &1, 2, u64::max_value(), WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		Balances::extend_lock(ID_1, &1, 8, u64::max_value(), WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 3), "account liquidity restrictions prevent withdrawal");
+	});
+}
+
+#[test]
+fn lock_reasons_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::Transfer.into());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1), "account liquidity restrictions prevent withdrawal");
+		assert_ok!(<Balances as Currency<_>>::reserve(&1, 1));
+		assert_ok!(<Balances as TransferAsset<_>>::withdraw(&1, 1, WithdrawReason::TransactionPayment));
+
+		Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::Reserve.into());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+		assert_noop!(<Balances as Currency<_>>::reserve(&1, 1), "account liquidity restrictions prevent withdrawal");
+		assert_ok!(<Balances as TransferAsset<_>>::withdraw(&1, 1, WithdrawReason::TransactionPayment));
+
+		Balances::set_lock(ID_1, &1, 10, u64::max_value(), WithdrawReason::TransactionPayment.into());
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+		assert_ok!(<Balances as Currency<_>>::reserve(&1, 1));
+		assert_noop!(<Balances as TransferAsset<_>>::withdraw(&1, 1, WithdrawReason::TransactionPayment), "account liquidity restrictions prevent withdrawal");
+	});
+}
+
+#[test]
+fn lock_block_number_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 10, 2, WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1), "account liquidity restrictions prevent withdrawal");
+
+		System::set_block_number(2);
+		assert_ok!(<Balances as TransferAsset<_>>::transfer(&1, &2, 1));
+	});
+}
+
+#[test]
+fn lock_block_number_extension_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 10, 2, WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		Balances::extend_lock(ID_1, &1, 10, 1, WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		System::set_block_number(2);
+		Balances::extend_lock(ID_1, &1, 10, 8, WithdrawReasons::all());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 3), "account liquidity restrictions prevent withdrawal");
+	});
+}
+
+#[test]
+fn lock_reasons_extension_should_work() {
+	with_externalities(&mut ExtBuilder::default().monied(true).build(), || {
+		Balances::set_lock(ID_1, &1, 10, 10, WithdrawReason::Transfer.into());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		Balances::extend_lock(ID_1, &1, 10, 10, WithdrawReasons::none());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+		Balances::extend_lock(ID_1, &1, 10, 10, WithdrawReason::Reserve.into());
+		assert_noop!(<Balances as TransferAsset<_>>::transfer(&1, &2, 6), "account liquidity restrictions prevent withdrawal");
+	});
+}

 #[test]
 fn default_indexing_on_new_accounts_should_not_work2() {
@@ -464,4 +593,4 @@ fn extra_balance_should_transfer() {
 			assert_ok!(Balances::transfer(Some(1).into(), 2, 256 * 5)); // Account 1 can send extra units gained
 		}
 	);
-}
+}
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 substrate-primitives = { path = "../../core/primitives", default-features = false }
@@ -22,7 +22,7 @@ runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"parity-codec/std",
 	"substrate-primitives/std",
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 pwasm-utils = { version = "0.6.1", default-features = false }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
@@ -30,7 +30,7 @@ consensus = { package = "srml-consensus", path = "../consensus" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"parity-codec/std",
 	"substrate-primitives/std",
@@ -20,8 +20,8 @@ use crate::gas::{GasMeter, Token, approx_gas_for_balance};

 use rstd::prelude::*;
 use runtime_primitives::traits::{CheckedAdd, CheckedSub, Zero};
+use srml_support::traits::WithdrawReason;
 use timestamp;
-use srml_support::traits::EnsureAccountLiquid;

 pub type BalanceOf<T> = <T as balances::Trait>::Balance;
 pub type AccountIdOf<T> = <T as system::Trait>::AccountId;
@@ -520,7 +520,7 @@ fn transfer<'a, T: Trait, V: Vm<T>, L: Loader<T>>(
 	if would_create && value < ctx.config.existential_deposit {
 		return Err("value too low to create account");
 	}
-	<T as balances::Trait>::EnsureAccountLiquid::ensure_account_liquid(transactor)?;
+	<balances::Module<T>>::ensure_account_can_withdraw(transactor, value, WithdrawReason::Transfer, new_from_balance)?;

 	let new_to_balance = match to_balance.checked_add(&value) {
 		Some(b) => b,
@@ -77,7 +77,6 @@ impl balances::Trait for Test {
 	type Balance = u64;
 	type OnFreeBalanceZero = Contract;
 	type OnNewAccount = ();
-	type EnsureAccountLiquid = ();
 	type Event = MetaEvent;
 }
 impl timestamp::Trait for Test {
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
@@ -29,6 +29,7 @@ std = [
 	"parity-codec-derive/std",
 	"substrate-primitives/std",
 	"rstd/std",
+	"serde",
 	"runtime_io/std",
 	"srml-support/std",
 	"primitives/std",
@@ -76,7 +76,6 @@ mod tests {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
-		type EnsureAccountLiquid = ();
 		type Event = Event;
 	}
 	impl democracy::Trait for Test {
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
@@ -23,7 +23,7 @@ balances = { package = "srml-balances", path = "../balances" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"safe-mix/std",
 	"parity-codec/std",
@@ -20,17 +20,19 @@

 use rstd::prelude::*;
 use rstd::result;
-use primitives::traits::{Zero, As};
+use primitives::traits::{Zero, As, Bounded};
 use parity_codec::{Encode, Decode};
 use srml_support::{StorageValue, StorageMap, Parameter, Dispatchable, IsSubType};
 use srml_support::{decl_module, decl_storage, decl_event, ensure};
-use srml_support::traits::{Currency, OnFreeBalanceZero, EnsureAccountLiquid, WithdrawReason, ArithmeticType};
+use srml_support::traits::{Currency, LockableCurrency, WithdrawReason, ArithmeticType, LockIdentifier};
 use srml_support::dispatch::Result;
 use system::ensure_signed;

 mod vote_threshold;
 pub use vote_threshold::{Approved, VoteThreshold};

+const DEMOCRACY_ID: LockIdentifier = *b"democrac";
+
 /// A proposal index.
 pub type PropIndex = u32;
 /// A referendum index.
@@ -68,7 +70,7 @@ impl Vote {
 type BalanceOf<T> = <<T as Trait>::Currency as ArithmeticType>::Type;

 pub trait Trait: system::Trait + Sized {
-	type Currency: ArithmeticType + Currency<<Self as system::Trait>::AccountId, Balance=BalanceOf<Self>>;
+	type Currency: ArithmeticType + LockableCurrency<<Self as system::Trait>::AccountId, Moment=Self::BlockNumber, Balance=BalanceOf<Self>>;

 	type Proposal: Parameter + Dispatchable<Origin=Self::Origin> + IsSubType<Module<Self>>;

@@ -208,9 +210,6 @@ decl_storage! {
 		/// Queue of successful referenda to be dispatched.
 		pub DispatchQueue get(dispatch_queue): map T::BlockNumber => Vec<Option<(T::Proposal, ReferendumIndex)>>;

-		/// The block at which the `who`'s funds become liquid.
-		pub Bondage get(bondage): map T::AccountId => T::BlockNumber;
-
 		/// Get the voters for the current proposal.
 		pub VotersFor get(voters_for): map ReferendumIndex => Vec<T::AccountId>;

@@ -371,7 +370,7 @@ impl<T: Trait> Module<T> {
 			// lock should they win...
 			let locked_until = now + lock_period * T::BlockNumber::sa((vote.multiplier()) as u64);
 			// ...extend their bondage until at least then.
-			<Bondage<T>>::mutate(a, |b| if *b < locked_until { *b = locked_until });
+			T::Currency::extend_lock(DEMOCRACY_ID, &a, Bounded::max_value(), locked_until, WithdrawReason::Transfer.into());
 		}

 		Self::clear_referendum(index);
@@ -409,35 +408,6 @@ impl<T: Trait> Module<T> {
 	}
 }

-impl<T: Trait> OnFreeBalanceZero<T::AccountId> for Module<T> {
-	fn on_free_balance_zero(who: &T::AccountId) {
-		<Bondage<T>>::remove(who);
-	}
-}
-
-impl<T: Trait> EnsureAccountLiquid<T::AccountId, BalanceOf<T>> for Module<T> {
-	fn ensure_account_liquid(who: &T::AccountId) -> Result {
-		if Self::bondage(who) > <system::Module<T>>::block_number() {
-			Err("stash accounts are not liquid")
-		} else {
-			Ok(())
-		}
-	}
-	fn ensure_account_can_withdraw(
-		who: &T::AccountId,
-		_value: BalanceOf<T>,
-		reason: WithdrawReason,
-	) -> Result {
-		if reason == WithdrawReason::TransactionPayment
-			|| Self::bondage(who) <= <system::Module<T>>::block_number()
-		{
-			Ok(())
-		} else {
-			Err("cannot transfer voting funds")
-		}
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -447,6 +417,7 @@ mod tests {
 	use primitives::BuildStorage;
 	use primitives::traits::{BlakeTwo256, IdentityLookup};
 	use primitives::testing::{Digest, DigestItem, Header};
+	use balances::BalanceLock;

 	const AYE: Vote = Vote(-1);
 	const NAY: Vote = Vote(0);
@@ -482,7 +453,6 @@ mod tests {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
-		type EnsureAccountLiquid = ();
 		type Event = ();
 	}
 	impl Trait for Test {
@@ -790,12 +760,12 @@ mod tests {

 			assert_eq!(Democracy::end_block(System::block_number()), Ok(()));

-			assert_eq!(Democracy::bondage(1), 0);
-			assert_eq!(Democracy::bondage(2), 6);
-			assert_eq!(Democracy::bondage(3), 5);
-			assert_eq!(Democracy::bondage(4), 4);
-			assert_eq!(Democracy::bondage(5), 3);
-			assert_eq!(Democracy::bondage(6), 0);
+			assert_eq!(Balances::locks(1), vec![]);
+			assert_eq!(Balances::locks(2), vec![BalanceLock { id: DEMOCRACY_ID, amount: u64::max_value(), until: 6, reasons: WithdrawReason::Transfer.into() }]);
+			assert_eq!(Balances::locks(3), vec![BalanceLock { id: DEMOCRACY_ID, amount: u64::max_value(), until: 5, reasons: WithdrawReason::Transfer.into() }]);
+			assert_eq!(Balances::locks(4), vec![BalanceLock { id: DEMOCRACY_ID, amount: u64::max_value(), until: 4, reasons: WithdrawReason::Transfer.into() }]);
+			assert_eq!(Balances::locks(5), vec![BalanceLock { id: DEMOCRACY_ID, amount: u64::max_value(), until: 3, reasons: WithdrawReason::Transfer.into() }]);
+			assert_eq!(Balances::locks(6), vec![]);

 			System::set_block_number(2);
 			assert_eq!(Democracy::end_block(System::block_number()), Ok(()));
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 srml-support = { path = "../support", default-features = false }
 system = { package = "srml-system", path = "../system", default-features = false }
@@ -20,7 +20,7 @@ sr-primitives = { path = "../../core/sr-primitives" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"sr-primitives/std",
 	"srml-support/std",
@@ -280,7 +280,6 @@ mod tests {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
-		type EnsureAccountLiquid = ();
 		type Event = ();
 	}
 	impl Trait for Test {
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
 runtime_io = { package = "sr-io", path = "../../core/sr-io", default-features = false }
@@ -26,7 +26,7 @@ default = ["std"]
 std = [
 	"rstd/std",
 	"srml-support/std",
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"primitives/std",
 	"runtime_io/std",
@@ -319,7 +319,6 @@ mod tests {
 		type Balance = u64;
 		type OnFreeBalanceZero = ();
 		type OnNewAccount = ();
-		type EnsureAccountLiquid = ();
 		type Event = MetaEvent;
 	}
 	impl fees::Trait for Runtime {
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
 primitives = { package = "substrate-primitives", path = "../../core/primitives", default-features = false }
@@ -19,7 +19,7 @@ system = { package = "srml-system", path = "../system", default-features = false
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"parity-codec-derive/std",
 	"primitives/std",
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 #hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 substrate-primitives = { path = "../../core/primitives", default-features = false }
@@ -24,7 +24,7 @@ runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"parity-codec/std",
 	"substrate-primitives/std",
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
@@ -24,7 +24,7 @@ ref_thread_local = "0.0"
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"substrate-keyring",
 	"parity-codec/std",
@@ -198,4 +198,7 @@ impl<T: Trait> StaticLookup for Module<T> {
 	fn lookup(a: Self::Source) -> result::Result<Self::Target, &'static str> {
 		Self::lookup_address(a).ok_or("invalid account index")
 	}
+	fn unlookup(a: Self::Target) -> Self::Source {
+		address::Address::Id(a)
+	}
 }
@@ -6,7 +6,7 @@ edition =  "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
@@ -24,7 +24,7 @@ runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"parity-codec/std",
 	"parity-codec-derive/std",
@@ -50,7 +50,7 @@ macro_rules! impl_session_change {

 for_each_tuple!(impl_session_change);

-pub trait Trait: timestamp::Trait {
+pub trait Trait: timestamp::Trait + consensus::Trait {
 	type ConvertAccountIdToSessionKey: Convert<Self::AccountId, Self::SessionKey>;
 	type OnSessionChange: OnSessionChange<Self::Moment>;
 	type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
@@ -6,11 +6,12 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 substrate-keyring = { path = "../../core/keyring", optional = true }
 rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
+runtime_io = { package = "sr-io", path = "../../core/sr-io", default-features = false }
 primitives = { package = "sr-primitives", path = "../../core/sr-primitives", default-features = false }
 srml-support = { path = "../support", default-features = false }
 consensus = { package = "srml-consensus", path = "../consensus", default-features = false }
@@ -19,18 +20,18 @@ session = { package = "srml-session", path = "../session", default-features = fa

 [dev-dependencies]
 substrate-primitives = { path = "../../core/primitives" }
-runtime_io = { package = "sr-io", path = "../../core/sr-io" }
 timestamp = { package = "srml-timestamp", path = "../timestamp" }
 balances = { package = "srml-balances", path = "../balances" }

 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"safe-mix/std",
 	"substrate-keyring",
 	"parity-codec/std",
 	"rstd/std",
+	"runtime_io/std",
 	"srml-support/std",
 	"primitives/std",
 	"session/std",
@@ -20,18 +20,20 @@

 #![cfg_attr(not(feature = "std"), no_std)]

+#[cfg(feature = "std")]
+use runtime_io::with_storage;
 use rstd::{prelude::*, result};
 use parity_codec::{HasCompact, Encode, Decode};
 use srml_support::{StorageValue, StorageMap, EnumerableStorageMap, dispatch::Result};
 use srml_support::{decl_module, decl_event, decl_storage, ensure};
 use srml_support::traits::{
-	Currency, OnDilution, EnsureAccountLiquid, OnFreeBalanceZero, WithdrawReason, ArithmeticType
+	Currency, OnDilution, OnFreeBalanceZero, ArithmeticType,
+	LockIdentifier, LockableCurrency, WithdrawReasons
 };
 use session::OnSessionChange;
 use primitives::Perbill;
-use primitives::traits::{Zero, One, As, StaticLookup, Saturating};
+use primitives::traits::{Zero, One, As, StaticLookup, Saturating, Bounded};
 use system::ensure_signed;
-
 mod mock;

 mod tests;
@@ -111,7 +113,11 @@ pub struct StakingLedger<AccountId, Balance: HasCompact, BlockNumber: HasCompact
 	pub unlocking: Vec<UnlockChunk<Balance, BlockNumber>>,
 }

-impl<AccountId, Balance: HasCompact + Copy + Saturating, BlockNumber: HasCompact + PartialOrd> StakingLedger<AccountId, Balance, BlockNumber> {
+impl<
+	AccountId,
+	Balance: HasCompact + Copy + Saturating,
+	BlockNumber: HasCompact + PartialOrd
+> StakingLedger<AccountId, Balance, BlockNumber> {
 	/// Remove entries from `unlocking` that are sufficiently old and reduce the
 	/// total by the sum of their balances.
 	fn consolidate_unlocked(self, current_era: BlockNumber) -> Self {
@@ -157,7 +163,10 @@ type BalanceOf<T> = <<T as Trait>::Currency as ArithmeticType>::Type;

 pub trait Trait: system::Trait + session::Trait {
 	/// The staking balance.
-	type Currency: ArithmeticType + Currency<Self::AccountId, Balance=BalanceOf<Self>>;
+	type Currency:
+		ArithmeticType +
+		Currency<Self::AccountId, Balance=BalanceOf<Self>> +
+		LockableCurrency<Self::AccountId, Moment=Self::BlockNumber>;

 	/// Some tokens minted.
 	type OnRewardMinted: OnDilution<BalanceOf<Self>>;
@@ -166,6 +175,8 @@ pub trait Trait: system::Trait + session::Trait {
 	type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
 }

+const STAKING_ID: LockIdentifier = *b"staking ";
+
 decl_storage! {
 	trait Store for Module<T: Trait> as Staking {

@@ -192,21 +203,9 @@ decl_storage! {
 		pub Invulnerables get(invulnerables) config(): Vec<T::AccountId>;

 		/// Map from all locked "stash" accounts to the controller account.
-		pub Bonded get(bonded) build(|config: &GenesisConfig<T>| {
-			config.stakers.iter().map(|(stash, controller, _)| (stash.clone(), controller.clone())).collect::<Vec<_>>()
-		}): map T::AccountId => Option<T::AccountId>;
+		pub Bonded get(bonded): map T::AccountId => Option<T::AccountId>;
 		/// Map from all (unlocked) "controller" accounts to the info regarding the staking.
-		pub Ledger get(ledger) build(|config: &GenesisConfig<T>| {
-			config.stakers.iter().map(|(stash, controller, value)| (
-				controller.clone(),
-				StakingLedger {
-					stash: stash.clone(),
-					total: *value,
-					active: *value,
-					unlocking: Vec::<UnlockChunk<BalanceOf<T>, T::BlockNumber>>::new(),
-				},
-			)).collect::<Vec<_>>()
-		}): map T::AccountId => Option<StakingLedger<T::AccountId, BalanceOf<T>, T::BlockNumber>>;
+		pub Ledger get(ledger): map T::AccountId => Option<StakingLedger<T::AccountId, BalanceOf<T>, T::BlockNumber>>;

 		/// Where the reward payment should be made.
 		pub Payee get(payee): map T::AccountId => RewardDestination;
@@ -214,12 +213,7 @@ decl_storage! {
 		/// The set of keys are all controllers that want to validate.
 		/// 
 		/// The values are the preferences that a validator has.
-		pub Validators get(validators) build(|config: &GenesisConfig<T>| {
-			config.stakers.iter().map(|(_stash, controller, _value)| (
-				controller.clone(),
-				ValidatorPrefs::<BalanceOf<T>>::default(),
-			)).collect::<Vec<_>>()
-		}): linked_map T::AccountId => ValidatorPrefs<BalanceOf<T>>;
+		pub Validators get(validators): linked_map T::AccountId => ValidatorPrefs<BalanceOf<T>>;

 		/// The set of keys are all controllers that want to nominate.
 		/// 
@@ -228,16 +222,7 @@ decl_storage! {

 		/// Nominators for a particular account that is in action right now. You can't iterate through validators here,
 		/// but you can find them in the `sessions` module.
-		pub Stakers get(stakers) build(|config: &GenesisConfig<T>| {
-			config.stakers.iter().map(|(_stash, controller, value)| (
-				controller.clone(),
-				Exposure {
-					total: *value,
-					own: *value,
-					others: Vec::<IndividualExposure<T::AccountId, _>>::new(),
-				},
-			)).collect::<Vec<_>>()
-		}): map T::AccountId => Exposure<T::AccountId, BalanceOf<T>>;
+		pub Stakers get(stakers): map T::AccountId => Exposure<T::AccountId, BalanceOf<T>>;

 		// The historical validators and their nominations for a given era. Stored as a trie root of the mapping
 		// `T::AccountId` => `Exposure<T::AccountId, BalanceOf<T>>`, which is just the contents of `Stakers`,
@@ -282,7 +267,16 @@ decl_storage! {
 	}
 	add_extra_genesis {
 		config(stakers): Vec<(T::AccountId, T::AccountId, BalanceOf<T>)>;
-	}
+		build(|storage: &mut primitives::StorageOverlay, _: &mut primitives::ChildrenStorageOverlay, config: &GenesisConfig<T>| {
+			with_storage(storage, || {
+				for &(ref stash, ref controller, balance) in &config.stakers {
+					let _ = <Module<T>>::bond(T::Origin::from(Some(stash.clone()).into()), T::Lookup::unlookup(controller.clone()), balance, RewardDestination::Staked);
+					let _ = <Module<T>>::validate(T::Origin::from(Some(controller.clone()).into()), Default::default());
+				}
+				<Module<T>>::select_validators();
+			});
+		});
+	}	
 }

 decl_module! {
@@ -307,7 +301,7 @@ decl_module! {
 			let stash_balance = T::Currency::free_balance(&stash);
 			let value = value.min(stash_balance);

-			<Ledger<T>>::insert(&controller, StakingLedger { stash, total: value, active: value, unlocking: vec![] });
+			Self::update_ledger(&controller, StakingLedger { stash, total: value, active: value, unlocking: vec![] });
 			<Payee<T>>::insert(&controller, payee);
 		}

@@ -326,7 +320,7 @@ decl_module! {
 				let extra = (stash_balance - ledger.total).min(max_additional);
 				ledger.total += extra;
 				ledger.active += extra;
-				<Ledger<T>>::insert(&controller, ledger);
+				Self::update_ledger(&controller, ledger);
 			}
 		}

@@ -358,7 +352,7 @@ decl_module! {

 				let era = Self::current_era() + Self::bonding_duration();
 				ledger.unlocking.push(UnlockChunk { value, era });
-				<Ledger<T>>::insert(&controller, ledger);
+				Self::update_ledger(&controller, ledger);
 			}
 		}

@@ -373,7 +367,8 @@ decl_module! {
 		fn withdraw_unbonded(origin) {
 			let controller = ensure_signed(origin)?;
 			let ledger = Self::ledger(&controller).ok_or("not a controller")?;
-			<Ledger<T>>::insert(&controller, ledger.consolidate_unlocked(Self::current_era()));
+			let ledger = ledger.consolidate_unlocked(Self::current_era());
+			Self::update_ledger(&controller, ledger);
 		}

 		/// Declare the desire to validate for the origin controller.
@@ -503,8 +498,14 @@ impl<T: Trait> Module<T> {
 		Self::stakers(who).total
 	}

-	// PUBLIC MUTABLES (DANGEROUS)
-	
+	// MUTABLES (DANGEROUS)
+
+	/// Update the ledger for a controller. This will also update the stash lock.
+	fn update_ledger(controller: &T::AccountId, ledger: StakingLedger<T::AccountId, BalanceOf<T>, T::BlockNumber>) {
+		T::Currency::set_lock(STAKING_ID, &ledger.stash, ledger.total, T::BlockNumber::max_value(), WithdrawReasons::all());
+		<Ledger<T>>::insert(controller, ledger);
+	}
+
 	/// Slash a given validator by a specific amount. Removes the slash from their balance by preference,
 	/// and reduces the nominators' balance if needed.
 	fn slash_validator(v: &T::AccountId, slash: BalanceOf<T>) {
@@ -540,13 +541,13 @@ impl<T: Trait> Module<T> {
 			RewardDestination::Stash => {
 				let _ = Self::ledger(who).map(|l| T::Currency::reward(&l.stash, amount));
 			}
-			RewardDestination::Staked => <Ledger<T>>::mutate(who, |ml| {
-				if let Some(l) = ml.as_mut() {
+			RewardDestination::Staked =>
+				if let Some(mut l) = Self::ledger(who) {
 					l.active += amount;
 					l.total += amount;
 					let _ = T::Currency::reward(&l.stash, amount);
-				}
-			}),
+					Self::update_ledger(who, l);
+				},
 		}		
 	}

@@ -626,7 +627,17 @@ impl<T: Trait> Module<T> {
 		}

 		// Reassign all Stakers.
+		let slot_stake = Self::select_validators();

+		// Update the balances for slashing/rewarding according to the stakes.
+		<CurrentOfflineSlash<T>>::put(Self::offline_slash() * slot_stake);
+		<CurrentSessionReward<T>>::put(Self::session_reward() * slot_stake);
+	}
+
+	/// Select a new validator set from the assembled stakers and their role preferences.
+	///
+	/// @returns the new SlotStake value.
+	fn select_validators() -> BalanceOf<T> {
 		// Map of (would-be) validator account to amount of stake backing it.
 		
 		// First, we pull all validators, together with their stash balance into a Vec (cpu=O(V), mem=O(V))
@@ -658,6 +669,7 @@ impl<T: Trait> Module<T> {
 		// cpu=O(V.log(s)) average, O(V.s) worst.
 		let count = Self::validator_count() as usize;
 		let candidates = if candidates.len() <= count {
+			candidates.sort_unstable_by(|a, b| b.1.total.cmp(&a.1.total));
 			candidates
 		} else {
 			candidates.into_iter().fold(vec![], |mut winners: Vec<(T::AccountId, Exposure<T::AccountId, BalanceOf<T>>)>, entry| {
@@ -700,9 +712,7 @@ impl<T: Trait> Module<T> {
 			&candidates.into_iter().map(|i| i.0).collect::<Vec<_>>()
 		);

-		// Update the balances for slashing/rewarding according to the stakes.
-		<CurrentOfflineSlash<T>>::put(Self::offline_slash() * slot_stake);
-		<CurrentSessionReward<T>>::put(Self::session_reward() * slot_stake);
+		slot_stake
 	}

 	/// Call when a validator is determined to be offline. `count` is the
@@ -769,29 +779,6 @@ impl<T: Trait> OnSessionChange<T::Moment> for Module<T> {
 	}
 }

-impl<T: Trait> EnsureAccountLiquid<T::AccountId, BalanceOf<T>> for Module<T> {
-	fn ensure_account_liquid(who: &T::AccountId) -> Result {
-		if <Bonded<T>>::exists(who) {
-			Err("stash accounts are not liquid")
-		} else {
-			Ok(())
-		}
-	}
-	fn ensure_account_can_withdraw(
-		who: &T::AccountId,
-		amount: BalanceOf<T>,
-		_reason: WithdrawReason,
-	) -> Result {
-		if let Some(controller) = Self::bonded(who) {
-			let ledger = Self::ledger(&controller).ok_or("stash without controller")?;
-			let free_balance = T::Currency::free_balance(&who);
-			ensure!(free_balance.saturating_sub(ledger.total) > amount,
-				"stash with too much under management");
-		}		
-		Ok(())
-	}
-}
-
 impl<T: Trait> OnFreeBalanceZero<T::AccountId> for Module<T> {
 	fn on_free_balance_zero(who: &T::AccountId) {
 		if let Some(controller) = <Bonded<T>>::take(who) {
@@ -54,7 +54,6 @@ impl balances::Trait for Test {
 	type Balance = u64;
 	type OnFreeBalanceZero = Staking;
 	type OnNewAccount = ();
-	type EnsureAccountLiquid = Staking;
 	type Event = ();
 }
 impl session::Trait for Test {
@@ -120,22 +119,22 @@ impl ExtBuilder {
 		self
 	}
 	pub fn build(self) -> runtime_io::TestExternalities<Blake2Hasher> {
-		let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
+		let (mut t, mut c) = system::GenesisConfig::<Test>::default().build_storage().unwrap();
 		let balance_factor = if self.existential_deposit > 0 {
 			256
 		} else {
 			1
 		};
-		t.extend(consensus::GenesisConfig::<Test>{
+		let _ = consensus::GenesisConfig::<Test>{
 			code: vec![],
 			authorities: vec![],
-		}.build_storage().unwrap().0);
-		t.extend(session::GenesisConfig::<Test>{
+		}.assimilate_storage(&mut t, &mut c);
+		let _ = session::GenesisConfig::<Test>{
 			session_length: self.session_length,
 			validators: vec![10, 20],
 			keys: vec![],
-		}.build_storage().unwrap().0);
-		t.extend(balances::GenesisConfig::<Test>{
+		}.assimilate_storage(&mut t, &mut c);
+		let _ = balances::GenesisConfig::<Test>{
 			balances: if self.monied {
 				if self.reward > 0 {
 					vec![(1, 10 * balance_factor), (2, 20 * balance_factor), (3, 300 * balance_factor), (4, 400 * balance_factor), (10, balance_factor), (11, balance_factor * 1000), (20, balance_factor), (21, balance_factor * 2000)]
@@ -149,8 +148,8 @@ impl ExtBuilder {
 			transfer_fee: 0,
 			creation_fee: 0,
 			vesting: vec![],
-		}.build_storage().unwrap().0);
-		t.extend(GenesisConfig::<Test>{
+		}.assimilate_storage(&mut t, &mut c);
+		let _ = GenesisConfig::<Test>{
 			sessions_per_era: self.sessions_per_era,
 			current_era: self.current_era,
 			stakers: vec![(11, 10, balance_factor * 1000), (21, 20, balance_factor * 2000)],
@@ -163,10 +162,10 @@ impl ExtBuilder {
 			current_offline_slash: 20,
 			offline_slash_grace: 0,
 			invulnerables: vec![],
-		}.build_storage().unwrap().0);
-		t.extend(timestamp::GenesisConfig::<Test>{
+		}.assimilate_storage(&mut t, &mut c);
+		let _ = timestamp::GenesisConfig::<Test>{
 			period: 5,
-		}.build_storage().unwrap().0);
+		}.assimilate_storage(&mut t, &mut c);
 		t.into()
 	}
 }
@@ -332,7 +332,7 @@ fn staking_should_work() {
 		assert_eq!(Staking::era_length(), 3);
 		assert_eq!(Staking::validator_count(), 2);
 		// remember + compare this along with the test.
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);
 		assert_ok!(Staking::set_bonding_duration(2));
 		assert_eq!(Staking::bonding_duration(), 2);

@@ -347,7 +347,7 @@ fn staking_should_work() {
 		Session::check_rotate_session(System::block_number());
 		assert_eq!(Staking::current_era(), 0);
 		// No effects will be seen so far.s
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);
 		

 		// --- Block 2: 
@@ -359,7 +359,7 @@ fn staking_should_work() {
 		Session::check_rotate_session(System::block_number());
 		assert_eq!(Staking::current_era(), 0);
 		// No effects will be seen so far. Era has not been yet triggered.
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);


 		// --- Block 3: the validators will now change. 
@@ -413,7 +413,7 @@ fn nominating_and_rewards_should_work() {
 		assert_eq!(Staking::era_length(), 1);
 		assert_eq!(Staking::validator_count(), 2);
 		assert_eq!(Staking::bonding_duration(), 3);
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);

 		// Set payee to controller
 		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));
@@ -447,7 +447,7 @@ fn nominating_and_rewards_should_work() {
 		Session::check_rotate_session(System::block_number());
 		assert_eq!(Staking::current_era(), 1);
 		// validators will not change, since selection currently is actually not dependent on nomination and votes, only stake.
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);
 		// avalidators must have already received some rewards.
 		assert_eq!(Balances::total_balance(&10), initial_balance + session_reward);
 		assert_eq!(Balances::total_balance(&20), initial_balance + session_reward);
@@ -487,7 +487,7 @@ fn nominators_also_get_slashed() {
 		// Account 10 has not been reported offline
 		assert_eq!(Staking::slash_count(&10), 0);
 		// initial validators
-		assert_eq!(Session::validators(), vec![10, 20]);
+		assert_eq!(Session::validators(), vec![20, 10]);

 		// Set payee to controller
 		assert_ok!(Staking::set_payee(Origin::signed(10), RewardDestination::Controller));
@@ -500,7 +500,7 @@ fn nominators_also_get_slashed() {
 		// 2 will nominate for 10
 		let nominator_stake = 500;
 		assert_ok!(Staking::bond(Origin::signed(1), 2, nominator_stake, RewardDestination::default()));
-		assert_ok!(Staking::nominate(Origin::signed(2), vec![10, 20]));
+		assert_ok!(Staking::nominate(Origin::signed(2), vec![20, 10]));

 		// new era, pay rewards,
 		System::set_block_number(2);
@@ -628,7 +628,7 @@ fn cannot_transfer_staked_balance() {
 		// Confirm account 11 (via controller 10) is totally staked
 		assert_eq!(Staking::stakers(&10).total, 1000);
 		// Confirm account 11 cannot transfer as a result
-		assert_noop!(Balances::transfer(Origin::signed(11), 20, 1), "stash with too much under management");
+		assert_noop!(Balances::transfer(Origin::signed(11), 20, 1), "account liquidity restrictions prevent withdrawal");

 		// Give account 11 extra free balance
 		Balances::set_free_balance(&11, 10000);
@@ -637,8 +637,6 @@ fn cannot_transfer_staked_balance() {
 	});
 }

-
-
 #[test]
 fn cannot_reserve_staked_balance() {
 	// Checks that a bonded account cannot reserve balance from free balance
@@ -650,7 +648,7 @@ fn cannot_reserve_staked_balance() {
 		// Confirm account 11 (via controller 10) is totally staked
 		assert_eq!(Staking::stakers(&10).total, 1000);
 		// Confirm account 11 cannot transfer as a result
-		assert_noop!(Balances::reserve(&11, 1), "stash with too much under management");
+		assert_noop!(Balances::reserve(&11, 1), "account liquidity restrictions prevent withdrawal");

 		// Give account 11 extra free balance
 		Balances::set_free_balance(&11, 10000);
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 parity-codec-derive = { version = "3.1", default-features = false }
 sr-std = { path = "../../core/sr-std", default-features = false }
@@ -22,7 +22,7 @@ substrate-primitives = { path = "../../core/primitives" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"parity-codec-derive/std",
 	"sr-std/std",
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = { version = "0.1.0", optional = true }
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 srml-metadata = { path = "../metadata", default-features = false }
@@ -17,6 +17,7 @@ inherents = { package = "substrate-inherents", path = "../../core/inherents", de
 srml-support-procedural = { path = "./procedural" }
 paste = "0.1"
 once_cell = { version = "0.1.6", default-features = false, optional = true }
+bitmask = { git = "https://github.com/paritytech/bitmask", default-features = false }

 [dev-dependencies]
 pretty_assertions = "0.5.1"
@@ -26,7 +27,8 @@ default = ["std"]
 std = [
 	"hex-literal",
 	"once_cell",
-	"serde/std",
+	"bitmask/std",
+	"serde",
 	"serde_derive",
 	"runtime_io/std",
 	"parity-codec/std",
@@ -232,9 +232,9 @@ fn decl_store_extra_genesis(
 						use #scrate::rstd::{cell::RefCell, marker::PhantomData};
 						use #scrate::codec::{Encode, Decode};

-						let storage = (RefCell::new(&mut r), PhantomData::<Self>::default());
 						let v = (#builder)(&self);
 						<#name<#traitinstance> as #scrate::storage::generator::StorageValue<#typ>>::put(&v, &storage);
+						
 					}}
 				},
 				DeclStorageTypeInfosKind::Map { key_type, .. } => {
@@ -242,7 +242,6 @@ fn decl_store_extra_genesis(
 						use #scrate::rstd::{cell::RefCell, marker::PhantomData};
 						use #scrate::codec::{Encode, Decode};

-						let storage = (RefCell::new(&mut r), PhantomData::<Self>::default());
 						let data = (#builder)(&self);
 						for (k, v) in data.into_iter() {
 							<#name<#traitinstance> as #scrate::storage::generator::StorageMap<#key_type, #typ>>::insert(&k, &v, &storage);
@@ -382,12 +381,28 @@ fn decl_store_extra_genesis(
 					let mut r: #scrate::runtime_primitives::StorageOverlay = Default::default();
 					let mut c: #scrate::runtime_primitives::ChildrenStorageOverlay = Default::default();

-					#builders
+					{
+						use #scrate::rstd::{cell::RefCell, marker::PhantomData};
+						let storage = (RefCell::new(&mut r), PhantomData::<Self>::default());
+						#builders
+					}

 					#scall(&mut r, &mut c, &self);

 					Ok((r, c))
 				}
+				fn assimilate_storage(self, r: &mut #scrate::runtime_primitives::StorageOverlay, c: &mut #scrate::runtime_primitives::ChildrenStorageOverlay) -> ::std::result::Result<(), String> {
+					use #scrate::rstd::{cell::RefCell, marker::PhantomData};
+					let storage = (RefCell::new(r), PhantomData::<Self>::default());
+
+					#builders
+
+					let r = storage.0.into_inner();
+
+					#scall(r, c, &self);
+
+					Ok(())
+				}
 			}
 		}
 	} else {
@@ -19,6 +19,9 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(not(feature = "std"), feature(alloc))]

+#[macro_use]
+extern crate bitmask;
+
 #[cfg(feature = "std")]
 pub use serde;
 #[doc(hidden)]
@@ -17,7 +17,7 @@
 //! Traits for SRML

 use crate::rstd::result;
-use crate::codec::Codec;
+use crate::codec::{Codec, Encode, Decode};
 use crate::runtime_primitives::traits::{
 	MaybeSerializeDebug, SimpleArithmetic, As
 };
@@ -53,61 +53,6 @@ impl<Balance> OnDilution<Balance> for () {
 	fn on_dilution(_minted: Balance, _portion: Balance) {}
 }

-/// Determinator for whether a given account is able to use its **free** balance.
-/// 
-/// By convention, `ensure_account_liquid` overrules `ensure_account_can_withdraw`. If a
-/// caller gets `Ok` from the former, then they do not need to call the latter.
-/// 
-/// This implies that if you define the latter away from its default of replicating the
-/// former, then ensure you also redefine the former to return an `Err` in corresponding
-/// situations, otherwise you'll end up giving inconsistent information.
-// TODO: Remove in favour of explicit functionality in balances module: #1896
-pub trait EnsureAccountLiquid<AccountId, Balance> {
-	/// Ensures that the account is completely unencumbered. If this is `Ok` then there's no need to
-	/// check any other items. If it's an `Err`, then you must use one pair of the other items.
-	fn ensure_account_liquid(who: &AccountId) -> result::Result<(), &'static str>;
-
-	/// Returns `Ok` iff the account is able to make a withdrawal of the given amount
-	/// for the given reason.
-	/// 
-	/// `Err(...)` with the reason why not otherwise.
-	/// 
-	/// By default this just reflects the results of `ensure_account_liquid`.
-	/// 
-	/// @warning If you redefine this away from the default, ensure that you define
-	/// `ensure_account_liquid` in accordance.
-	fn ensure_account_can_withdraw(
-		who: &AccountId,
-		_amount: Balance,
-		_reason: WithdrawReason
-	) -> result::Result<(), &'static str> {
-		Self::ensure_account_liquid(who)
-	}
-}
-impl<
-	AccountId,
-	Balance: Copy,
-	X: EnsureAccountLiquid<AccountId, Balance>,
-	Y: EnsureAccountLiquid<AccountId, Balance>,
-> EnsureAccountLiquid<AccountId, Balance> for (X, Y) {
-	fn ensure_account_liquid(who: &AccountId) -> result::Result<(), &'static str> {
-		X::ensure_account_liquid(who)?;
-		Y::ensure_account_liquid(who)
-	}
-
-	fn ensure_account_can_withdraw(
-		who: &AccountId,
-		amount: Balance,
-		reason: WithdrawReason
-	) -> result::Result<(), &'static str> {
-		X::ensure_account_can_withdraw(who, amount, reason)?;
-		Y::ensure_account_can_withdraw(who, amount, reason)
-	}
-}
-impl<AccountId, Balance> EnsureAccountLiquid<AccountId, Balance> for () {
-	fn ensure_account_liquid(_who: &AccountId) -> result::Result<(), &'static str> { Ok(()) }
-}
-
 /// Outcome of a balance update.
 pub enum UpdateBalanceOutcome {
 	/// Account balance was simply updated.
@@ -227,6 +172,41 @@ pub trait Currency<AccountId> {
 	) -> result::Result<Option<Self::Balance>, &'static str>;
 }

+/// An identifier for a lock. Used for disambiguating different locks so that
+/// they can be individually replaced or removed.
+pub type LockIdentifier = [u8; 8];
+
+/// A currency whose accounts can have liquidity restructions.
+pub trait LockableCurrency<AccountId>: Currency<AccountId> {
+	/// The quantity used to denote time; usually just a `BlockNumber`.
+	type Moment;
+
+	/// Introduce a new lock or change an existing one.
+	fn set_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+		amount: Self::Balance,
+		until: Self::Moment,
+		reasons: WithdrawReasons,
+	);
+
+	/// Change any existing lock so that it becomes strictly less liquid in all
+	/// respects to the given parameters.
+	fn extend_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+		amount: Self::Balance,
+		until: Self::Moment,
+		reasons: WithdrawReasons,
+	);
+
+	/// Remove an existing lock.
+	fn remove_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+	);
+}
+
 /// Charge bytes fee trait
 pub trait ChargeBytesFee<AccountId> {
 	/// Charge fees from `transactor` for an extrinsic (transaction) of encoded length
@@ -246,16 +226,21 @@ pub trait ChargeFee<AccountId>: ChargeBytesFee<AccountId> {
 	fn refund_fee(transactor: &AccountId, amount: Self::Amount) -> Result<(), &'static str>;
 }

-/// Reason for moving funds out of an account.
-#[derive(Copy, Clone, Eq, PartialEq)]
-#[cfg_attr(feature = "std", derive(Debug))]
-pub enum WithdrawReason {
-	/// In order to pay for (system) transaction costs.
-	TransactionPayment,
-	/// In order to transfer ownership.
-	Transfer,
-	/// In order to reserve some funds for a later return or repatriation
-	Reserve,
+bitmask! {
+	/// Reasons for moving funds out of an account.
+	#[derive(Encode, Decode)]
+	pub mask WithdrawReasons: i8 where
+
+	/// Reason for moving funds out of an account.
+	#[derive(Encode, Decode)]
+	flags WithdrawReason {
+		/// In order to pay for (system) transaction costs.
+		TransactionPayment = 0b00000001,
+		/// In order to transfer ownership.
+		Transfer = 0b00000010,
+		/// In order to reserve some funds for a later return or repatriation
+		Reserve = 0b00000100,
+	}
 }

 /// Transfer fungible asset trait
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 safe-mix = { version = "1.0", default-features = false}
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
@@ -19,7 +19,7 @@ srml-support = { path = "../support", default-features = false }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"safe-mix/std",
 	"parity-codec/std",
@@ -6,14 +6,13 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
 runtime_primitives = { package = "sr-primitives", path = "../../core/sr-primitives", default-features = false }
 inherents = { package = "substrate-inherents", path = "../../core/inherents", default-features = false }
 srml-support = { path = "../support", default-features = false }
 system = { package = "srml-system", path = "../system", default-features = false }
-consensus = { package = "srml-consensus", path = "../consensus", default-features = false }

 [dev-dependencies]
 runtime_io = { package = "sr-io", path = "../../core/sr-io" }
@@ -25,8 +24,7 @@ std = [
 	"rstd/std",
 	"srml-support/std",
 	"runtime_primitives/std",
-	"consensus/std",
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"system/std",
 	"inherents/std",
@@ -32,17 +32,17 @@

 #![cfg_attr(not(feature = "std"), no_std)]

+use parity_codec::Encode;
 #[cfg(feature = "std")]
 use parity_codec::Decode;
-use parity_codec::Encode;
+#[cfg(feature = "std")]
+use inherents::ProvideInherentData;
 use srml_support::{StorageValue, Parameter, decl_storage, decl_module};
 use srml_support::for_each_tuple;
 use runtime_primitives::traits::{As, SimpleArithmetic, Zero};
 use system::ensure_inherent;
 use rstd::{result, ops::{Mul, Div}, cmp};
 use inherents::{RuntimeString, InherentIdentifier, ProvideInherent, IsFatalError, InherentData};
-#[cfg(feature = "std")]
-use inherents::ProvideInherentData;

 /// The identifier for the `timestamp` inherent.
 pub const INHERENT_IDENTIFIER: InherentIdentifier = *b"timstap0";
@@ -144,7 +144,7 @@ macro_rules! impl_timestamp_set {

 for_each_tuple!(impl_timestamp_set);

-pub trait Trait: consensus::Trait + system::Trait {
+pub trait Trait: system::Trait {
 	/// Type used for expressing timestamp.
 	type Moment: Parameter + Default + SimpleArithmetic
 		+ Mul<Self::BlockNumber, Output = Self::Moment>
@@ -259,7 +259,7 @@ mod tests {
 	use substrate_primitives::H256;
 	use runtime_primitives::BuildStorage;
 	use runtime_primitives::traits::{BlakeTwo256, IdentityLookup};
-	use runtime_primitives::testing::{Digest, DigestItem, Header, UintAuthorityId};
+	use runtime_primitives::testing::{Digest, DigestItem, Header};

 	impl_outer_origin! {
 		pub enum Origin for Test {}
@@ -280,11 +280,6 @@ mod tests {
 		type Event = ();
 		type Log = DigestItem;
 	}
-	impl consensus::Trait for Test {
-		type Log = DigestItem;
-		type SessionKey = UintAuthorityId;
-		type InherentOfflineReport = ();
-	}
 	impl Trait for Test {
 		type Moment = u64;
 		type OnTimestampSet = ();
@@ -6,7 +6,7 @@ edition = "2018"

 [dependencies]
 hex-literal = "0.1.0"
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 serde_derive = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false, features = ["derive"] }
 rstd = { package = "sr-std", path = "../../core/sr-std", default-features = false }
@@ -22,7 +22,7 @@ substrate-primitives = { path = "../../core/primitives" }
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"serde_derive",
 	"parity-codec/std",
 	"rstd/std",
@@ -287,7 +287,6 @@ mod tests {
 		type Balance = u64;
 		type OnNewAccount = ();
 		type OnFreeBalanceZero = ();
-		type EnsureAccountLiquid = ();
 		type Event = ();
 	}
 	impl Trait for Test {
@@ -5,7 +5,7 @@ authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"

 [dependencies]
-serde = { version = "1.0", default-features = false }
+serde = { version = "1.0", optional = true }
 parity-codec = { version = "3.1", default-features = false }
 sr-std = { path = "../../core/sr-std", default-features = false }
 sr-primitives = { path = "../../core/sr-primitives", default-features = false }
@@ -16,7 +16,7 @@ consensus = { package = "srml-consensus", path = "../consensus", default-feature
 [features]
 default = ["std"]
 std = [
-	"serde/std",
+	"serde",
 	"parity-codec/std",
 	"sr-std/std",
 	"sr-primitives/std",