Transaction Weights (#62)

* Brainstorm compiles.

* Module fleshed out completely.

* Runtime demonstrating WeightToFee

* One more weight example.

* line width to 100.

* Put some text in recipes. Will be nicer after #43

* Complete links to devhub.

* Revert accidental change to weight module which broke compile.

* Update kitchen/modules/weights/src/lib.rs

Co-Authored-By: Amar Singh <asinghchrony@protonmail.com>

* Update src/design/econsecurity.md

Co-Authored-By: Amar Singh <asinghchrony@protonmail.com>

* Correct example WeightToFee = ConvertInto.

* Update src/design/econsecurity.md

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* Add Kian's suggested warning.

* cleanup formatting characters

* Add Amar's suggested warning.

kitchen/modules/weights/Cargo.toml

@@ -0,0 +1,50 @@
+[package]
+name = "weights"
+version = "0.1.0"
+authors = ["Anonymous"]
+edition = "2018"
+
+[features]
+default = ['std']
+std = [
+    'parity-scale-codec/std',
+    'support/std',
+    'system/std',
+    'balances/std',
+    'runtime-primitives/std',
+]
+
+[dependencies.parity-scale-codec]
+default-features = false
+features = ['derive']
+version = '1.0.6'
+
+[dependencies.support]
+default_features = false
+git = 'https://github.com/paritytech/substrate.git'
+package = 'srml-support'
+branch = 'master'
+
+[dependencies.system]
+default_features = false
+git = 'https://github.com/paritytech/substrate.git'
+package = 'srml-system'
+branch = 'master'
+
+[dependencies.balances]
+default_features = false
+git = 'https://github.com/paritytech/substrate.git'
+package = 'srml-balances'
+branch = 'master'
+
+[dependencies.runtime-primitives]
+default_features = false
+git = 'https://github.com/paritytech/substrate.git'
+package = 'sr-primitives'
+branch = 'master'
+
+[dev-dependencies.primitives]
+default_features = false
+git = 'https://github.com/paritytech/substrate.git'
+package = 'substrate-primitives'
+branch = 'master'

kitchen/modules/weights/src/lib.rs

@@ -0,0 +1,181 @@
+#![cfg_attr(not(feature = "std"), no_std)]
+
+// Transaction Weight Examples
+// https://crates.parity.io/sr_primitives/weights/index.html
+use support::{ensure, decl_module, decl_storage, dispatch::{Result, WeighData}};
+use runtime_primitives::weights::{ DispatchClass, Weight, ClassifyDispatch, SimpleDispatchInfo };
+
+pub trait Trait: system::Trait {}
+
+decl_storage! {
+	trait Store for Module<T: Trait> as SimpleMap {
+		StoredValue get(stored_value): u32;
+	}
+}
+
+// A "scale" to weigh transactions. This scale can be used with any transactions that take a
+// single argument of type u32. The ultimate weight of the transaction is the / product of the
+// transaction parameter and the field of this struct.
+pub struct Linear(u32);
+
+// The actual weight calculation happens in the
+// impl WeighData block
+impl WeighData<(&u32,)> for Linear {
+	fn weigh_data(&self, (x,): (&u32,)) -> Weight {
+
+		// Use saturation so that an extremely large parameter value
+		// Does not cause overflow.
+		x.saturating_mul(self.0)
+	}
+}
+
+// Any struct that is used to weigh data must also implement ClassifyDispatchInfo. Here we classify
+// the transaction as Normal (as opposed to operational.)
+impl<T> ClassifyDispatch<T> for Linear {
+	fn classify_dispatch(&self, _: T) -> DispatchClass {
+		// Classify all calls as Normal (which is the default)
+		Default::default()
+	}
+}
+
+// Another scale to weight transactions. This one is more complex. / It computes weight according
+// to the formula a*x^2 + b*y + c where / a, b, and c are fields in the struct, and x and y are
+// transaction / parameters.
+pub struct Quadratic(u32, u32, u32);
+
+impl WeighData<(&u32, &u32)> for Quadratic {
+	fn weigh_data(&self, (x, y): (&u32, &u32)) -> Weight {
+
+		let ax2 = x.saturating_mul(*x).saturating_mul(self.0);
+		let by = y.saturating_mul(self.1);
+		let c = self.2;
+
+		ax2.saturating_add(by).saturating_add(c)
+	}
+}
+
+impl<T> ClassifyDispatch<T> for Quadratic {
+	fn classify_dispatch(&self, _: T) -> DispatchClass {
+		// Classify all calls as Normal (which is the default)
+		Default::default()
+	}
+}
+
+// A final scale to weight transactions. This one weighs transactions where the first parameter
+// is bool. If the bool is true, then the weight is linear in the second parameter. Otherwise
+// the weight is constant.
+pub struct Conditional(u32);
+
+impl WeighData<(&bool, &u32)> for Conditional {
+	fn weigh_data(&self, (switch, val): (&bool, &u32)) -> Weight {
+
+		if *switch {
+			val.saturating_mul(self.0)
+		}
+		else {
+			self.0
+		}
+	}
+}
+
+impl<T> ClassifyDispatch<T> for Conditional {
+	fn classify_dispatch(&self, _: T) -> DispatchClass {
+		// Classify all calls as Normal (which is the default)
+		Default::default()
+	}
+}
+
+decl_module! {
+	pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+
+		// Store value does not loop at all so a fixed weight is appropriate. Fixed weights can
+		// be assigned using types available in the Substrate framework. No custom coding is
+		// necessary.
+		#[weight = SimpleDispatchInfo::FixedNormal(100)]
+		fn store_value(_origin, entry: u32) -> Result {
+
+			StoredValue::put(entry);
+
+			Ok(())
+		}
+
+		// WARNING: The functions that follow, allow the caller to control the
+		// amount of computation being performed. This is ONLY SAFE when using
+		// custom weighting structs as shown here.
+
+		// add_n sets the storage value n times, so it should cost n times as much as
+		// store_value. Because it performs both a read and a write, the multiplier is set to 200
+		// instead of 100 as before.
+		#[weight = Linear(200)]
+		fn add_n(_origin, n: u32) -> Result {
+
+			let mut old : u32;
+			for _i in 1..=n {
+				old = StoredValue::get();
+				StoredValue::put(old + 1);
+			}
+			Ok(())
+		}
+
+		// The actual expense of `double` is proportional to a storage value. Dispatch
+		// weightings can't use storage values directly, because the weight should be computable
+		// ahead of time. Instead we have the caller pass in the expected storage value and we
+		// ensure it is correct.
+		#[weight = Linear(200)]
+		fn double(_origin, initial_value: u32) -> Result {
+
+			// Ensure the value passed by the caller actually matches storage If this condition
+			// were not true, the caller would be able to avoid paying appropriate fees.
+			let initial = StoredValue::get();
+			ensure!(initial == initial_value, "Storage value did not match parameter");
+
+			for _i in 1..=initial {
+				let old = StoredValue::get();
+				StoredValue::put(old + 1);
+			}
+			Ok(())
+		}
+
+		// This one is quadratic in the first argument plus linear in the second plus a constant.
+		// This calculation is not meant to do something really useful or common other than
+		// demonstrate that weights should grow by the same order as the compute required by the
+		// transaction.
+		#[weight = Quadratic(200, 30, 100)]
+		fn complex_calculations(_origin, x: u32, y: u32) -> Result {
+			// This first part performs a relatively cheap (hence 30)
+			// in-memory calculations.
+			let mut part1 = 0;
+			for _i in 1..=y {
+				part1 += 2
+			}
+
+			// The second part performs x^2 storage read-writes (hence 200)
+			for _j in 1..=x {
+				for _k in 1..=x {
+					StoredValue::put(StoredValue::get() + 1);
+				}
+			}
+
+			// One final storage write (hence 100)
+			StoredValue::put(part1);
+
+			Ok(())
+		}
+
+		// Here the first parameter, a boolean has a significant effect on the computational
+		// intensity of the call.
+		#[weight = Conditional(200)]
+		fn add_or_set(_origin, add_flag: bool, val: u32) -> Result {
+			if add_flag {
+				StoredValue::put(&val);
+			}
+			else {
+				for _i in 1..=val {
+					StoredValue::put(StoredValue::get());
+				}
+			}
+
+			Ok(())
+		}
+	}
+}

kitchen/node/Cargo.toml

@@ -38,6 +38,8 @@ basic-authorship = { package = "substrate-basic-authorship", git = 'https://gith
 # Your runtime must have the necessary runtime modules to support consensus (Babe, Grandpa, etc)
 runtime = { package = "super-runtime", path = "../runtimes/super-runtime" }
 runtime-genesis = { package = "super-genesis", path = "../runtimes/super-genesis" }
+# runtime = { package = "weight-fee-runtime", path = "../runtimes/weight-fee-runtime"}
+# runtime-genesis = { package = "weight-fee-genesis", path = "../runtimes/weight-fee-genesis"}
 
 [build-dependencies]
 vergen = "3.0.4"

kitchen/runtimes/super-genesis/Cargo.toml

@@ -4,7 +4,7 @@ version = "2.0.0"
 authors = ["Anonymous"]
 edition = "2018"
 
-[dependencies.super-runtime]
+[dependencies.runtime]
 package = 'super-runtime'
 path = '../super-runtime'
 

kitchen/runtimes/super-genesis/src/lib.rs

@@ -1,4 +1,4 @@
-use super_runtime::{
+use runtime::{
 	AccountId, BabeConfig, BalancesConfig, GenesisConfig, GrandpaConfig,
 	SudoConfig, IndicesConfig, SystemConfig, WASM_BINARY,
 };

kitchen/runtimes/super-runtime/Cargo.toml

@@ -26,7 +26,7 @@ schedule-on-finalize = { package = "schedule-on-finalize", path = "../../modules
 [dependencies.parity-scale-codec]
 default-features = false
 features = ['derive']
-version = '1.0.6' # v1.0.0 indevhub/node-template
+version = '1.0.6'
 
 [dependencies.rstd]
 default-features = false

kitchen/runtimes/super-runtime/src/lib.rs

@@ -258,6 +258,20 @@ impl sudo::Trait for Runtime {
 	type Proposal = Call;
 }
 
+parameter_types! {
+	pub const TransactionBaseFee: u128 = 0;
+	pub const TransactionByteFee: u128 = 1;
+}
+
+impl transaction_payment::Trait for Runtime {
+	type Currency = balances::Module<Runtime>;
+	type OnTransactionPayment = ();
+	type TransactionBaseFee = TransactionBaseFee;
+	type TransactionByteFee = TransactionByteFee;
+	type WeightToFee = ConvertInto;
+	type FeeMultiplierUpdate = ();
+}
+
 // ---------------------- Recipe Runtime Configurations ----------------------
 impl simple_event::Trait for Runtime {
 	type Event = Event;
@@ -321,20 +335,6 @@ impl schedule_on_finalize::Trait for Runtime {
 	type ExecutionFrequency = ClearFrequency; // for convenience (can use a different constant)
 }
 
-parameter_types! {
-	pub const TransactionBaseFee: u128 = 0;
-	pub const TransactionByteFee: u128 = 1;
-}
-
-impl transaction_payment::Trait for Runtime {
-	type Currency = balances::Module<Runtime>;
-	type OnTransactionPayment = ();
-	type TransactionBaseFee = TransactionBaseFee;
-	type TransactionByteFee = TransactionByteFee;
-	type WeightToFee = ConvertInto;
-	type FeeMultiplierUpdate = ();
-}
-
 construct_runtime!(
 	pub enum Runtime where
 		Block = Block,

kitchen/runtimes/weight-fee-genesis/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = 'weight-fee-genesis'
+version = "2.0.0"
+authors = ["Anonymous"]
+edition = "2018"
+
+[dependencies.runtime]
+package = 'weight-fee-runtime'
+path = '../weight-fee-runtime'
+
+[dependencies]
+babe-primitives = { package = "substrate-consensus-babe-primitives", git = "https://github.com/paritytech/substrate", branch = "master" }
+grandpa-primitives = { package = "substrate-finality-grandpa-primitives", git = "https://github.com/paritytech/substrate", branch = "master" }

kitchen/runtimes/weight-fee-genesis/src/lib.rs

@@ -0,0 +1,34 @@
+use runtime::{
+	AccountId, BabeConfig, BalancesConfig, GenesisConfig, GrandpaConfig,
+	SudoConfig, IndicesConfig, SystemConfig, WASM_BINARY,
+};
+use babe_primitives::{AuthorityId as BabeId};
+use grandpa_primitives::{AuthorityId as GrandpaId};
+
+pub fn testnet_genesis(initial_authorities: Vec<(AccountId, AccountId, GrandpaId, BabeId)>,
+	root_key: AccountId,
+	endowed_accounts: Vec<AccountId>,
+	_enable_println: bool) -> GenesisConfig {
+	GenesisConfig {
+		system: Some(SystemConfig {
+			code: WASM_BINARY.to_vec(),
+			changes_trie_config: Default::default(),
+		}),
+		indices: Some(IndicesConfig {
+			ids: endowed_accounts.clone(),
+		}),
+		balances: Some(BalancesConfig {
+			balances: endowed_accounts.iter().cloned().map(|k|(k, 1 << 60)).collect(),
+			vesting: vec![],
+		}),
+		sudo: Some(SudoConfig {
+			key: root_key,
+		}),
+		babe: Some(BabeConfig {
+			authorities: initial_authorities.iter().map(|x| (x.3.clone(), 1)).collect(),
+		}),
+		grandpa: Some(GrandpaConfig {
+			authorities: initial_authorities.iter().map(|x| (x.2.clone(), 1)).collect(),
+		}),
+	}
+}