Transaction Fee Module (#1648)

* wip

* Split bytes fee charging and charging by amount into different traits.

* Move to edition 2018.

* Implemented charge fee traits for fees module.

* Implemented 'on_finalise' for fee module.

* Updated fees finalize impl.

* Renaming and documentation update.

* Added overflow & underflow check for fee calculation.

* Added mock and unit tests for fee module.

* More unit tests for fees module.

* Fixed srml-executive unit tests.

* Remove transaction base/bytes fee from balances module, fix unit tests.

* fix compile error

* Fixed unit test.

* Minor fixes.

* Bump spec version.

* Bump spec version.

* Updated fees module and runtime wasm.

* Fees module code style improvement; updated runtime wasm.

* Bump spec and impl version.

substrate/node/runtime/Cargo.toml

@@ -31,6 +31,7 @@ timestamp = { package = "srml-timestamp", path = "../../srml/timestamp", default
 treasury = { package = "srml-treasury", path = "../../srml/treasury", default-features = false }
 sudo = { package = "srml-sudo", path = "../../srml/sudo", default-features = false }
 srml-upgrade-key = { path = "../../srml/upgrade-key", default-features = false }
+fees = { package = "srml-fees", path = "../../srml/fees", default-features = false }
 node-primitives = { path = "../primitives", default-features = false }
 consensus_aura = { package = "substrate-consensus-aura-primitives", path = "../../core/consensus/aura/primitives", default-features = false }
 rustc-hex = { version = "2.0", optional = true }
@@ -61,6 +62,7 @@ std = [
 	"treasury/std",
 	"sudo/std",
 	"srml-upgrade-key/std",
+	"fees/std",
 	"version/std",
 	"node-primitives/std",
 	"serde/std",

substrate/node/runtime/src/lib.rs

@@ -60,7 +60,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	spec_name: create_runtime_str!("node"),
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
-	spec_version: 28,
+	spec_version: 29,
 	impl_version: 29,
 	apis: RUNTIME_API_VERSIONS,
 };
@@ -107,6 +107,12 @@ impl balances::Trait for Runtime {
 	type Event = Event;
 }
 
+impl fees::Trait for Runtime {
+	type Event = Event;
+	type Amount = Balance;
+	type TransferAsset = Balances;
+}
+
 impl consensus::Trait for Runtime {
 	type Log = Log;
 	type SessionKey = SessionKey;
@@ -210,6 +216,7 @@ construct_runtime!(
 		Treasury: treasury,
 		Contract: contract::{Module, Call, Storage, Config<T>, Event<T>},
 		Sudo: sudo,
+		Fees: fees::{Module, Storage, Config<T>, Event<T>},
 	}
 );
 
@@ -228,7 +235,7 @@ pub type UncheckedExtrinsic = generic::UncheckedMortalCompactExtrinsic<Address,
 /// Extrinsic type that has already been checked.
 pub type CheckedExtrinsic = generic::CheckedExtrinsic<AccountId, Index, Call>;
 /// Executive: handles dispatch to the various modules.
-pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Balances, AllModules>;
+pub type Executive = executive::Executive<Runtime, Block, system::ChainContext<Runtime>, Fees, AllModules>;
 
 impl_runtime_apis! {
 	impl client_api::Core<Block> for Runtime {

substrate/node/runtime/wasm/Cargo.lock

@@ -651,6 +651,7 @@ dependencies = [
  "srml-council 0.1.0",
  "srml-democracy 0.1.0",
  "srml-executive 0.1.0",
+ "srml-fees 0.1.0",
  "srml-grandpa 0.1.0",
  "srml-indices 0.1.0",
  "srml-session 0.1.0",
@@ -1349,6 +1350,7 @@ dependencies = [
  "sr-sandbox 0.1.0",
  "sr-std 0.1.0",
  "srml-balances 0.1.0",
+ "srml-fees 0.1.0",
  "srml-support 0.1.0",
  "srml-system 0.1.0",
  "srml-timestamp 0.1.0",
@@ -1402,6 +1404,22 @@ dependencies = [
  "srml-system 0.1.0",
 ]
 
+[[package]]
+name = "srml-fees"
+version = "0.1.0"
+dependencies = [
+ "hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec 3.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-codec-derive 3.0.0 (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-support 0.1.0",
+ "srml-system 0.1.0",
+ "substrate-primitives 0.1.0",
+]
+
 [[package]]
 name = "srml-grandpa"
 version = "0.1.0"