Extensible transactions (and tips) (#3102)

* Make extrinsics extensible.

Also Remove old extrinsic types.

* Rest of mockup. Add tips.

* Fix some build issues

* Runtiem builds :)

* Substrate builds.

* Fix a doc test

* Compact encoding

* Extract out the era logic into an extension

* Weight Check signed extension. (#3115)

* Weight signed extension.

* Revert a bit + test for check era.

* Update Cargo.toml

* Update node/cli/src/factory_impl.rs

* Update node/executor/src/lib.rs

* Update node/executor/src/lib.rs

* Don't use len for weight - use data.

* Operational Transaction; second attempt (#3138)

* working poc added.

* some fixes.

* Update doc.

* Fix all tests + final logic.

* more refactoring.

* nits.

* System block limit in bytes.

* Silent the storage macro warnings.

* More logic more tests.

* Fix import.

* Refactor names.

* Fix build.

* Update srml/balances/src/lib.rs

* Final refactor.

* Bump transaction version

* Fix weight mult test.

* Fix more tests and improve doc.

* Bump.

* Make some tests work again.

* Fix subkey.

* Remove todos + bump.

* Ignore expensive test.

* Bump.

substrate/core/sr-primitives/src/weights.rs

@@ -17,8 +17,8 @@
 //! Primitives for transaction weighting.
 //!
 //! Each dispatch function within `decl_module!` can have an optional `#[weight = $x]` attribute.
-//!  $x can be any object that implements the `Weighable` trait. By default, All transactions are
-//! annotated by `#[weight = TransactionWeight::default()]`.
+//! `$x` can be any type that implements the `ClassifyDispatch<T>` and `WeighData<T>` traits. By
+//! default, All transactions are annotated with `#[weight = SimpleDispatchInfo::default()]`.
 //!
 //! Note that the decl_module macro _cannot_ enforce this and will simply fail if an invalid struct
 //! (something that does not  implement `Weighable`) is passed in.
@@ -26,59 +26,147 @@
 use crate::{Fixed64, traits::Saturating};
 use crate::codec::{Encode, Decode};
 
-/// The final type that each `#[weight = $x:expr]`'s
-/// expression must evaluate to.
+pub use crate::transaction_validity::TransactionPriority;
+use crate::traits::Bounded;
+
+/// Numeric range of a transaction weight.
 pub type Weight = u32;
 
-/// Maximum block saturation: 4mb
-pub const MAX_TRANSACTIONS_WEIGHT: u32 = 4 * 1024 * 1024;
-/// Target block saturation: 25% of max block saturation = 1mb
-pub const IDEAL_TRANSACTIONS_WEIGHT: u32 = MAX_TRANSACTIONS_WEIGHT / 4;
-
-/// A `Call` enum (aka transaction) that can be weighted using the custom weight attribute of
-/// its dispatchable functions. Is implemented by default in the `decl_module!`.
-///
-/// Both the outer Call enum and the per-module individual ones will implement this.
-/// The outer enum simply calls the inner ones based on call type.
-pub trait Weighable {
-	/// Return the weight of this call.
-	/// The `len` argument is the encoded length of the transaction/call.
-	fn weight(&self, len: usize) -> Weight;
+/// A generalized group of dispatch types. This is only distinguishing normal, user-triggered transactions
+/// (`Normal`) and anything beyond which serves a higher purpose to the system (`Operational`).
+#[cfg_attr(feature = "std", derive(Debug))]
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub enum DispatchClass {
+	/// A normal dispatch.
+	Normal,
+	/// An operational dispatch.
+	Operational,
 }
 
-/// Default type used as the weight representative in a `#[weight = x]` attribute.
-///
-/// A user may pass in any other type that implements [`Weighable`]. If not, the `Default`
-/// implementation of [`TransactionWeight`] is used.
-pub enum TransactionWeight {
-	/// Basic weight (base, byte).
-	/// The values contained are the base weight and byte weight respectively.
-	Basic(Weight, Weight),
-	/// Maximum fee. This implies that this transaction _might_ get included but
-	/// no more transaction can be added. This can be done by setting the
-	/// implementation to _maximum block weight_.
-	Max,
-	/// Free. The transaction does not increase the total weight
-	/// (i.e. is not included in weight calculation).
-	Free,
+impl Default for DispatchClass {
+	fn default() -> Self {
+		DispatchClass::Normal
+	}
 }
 
-impl Weighable for TransactionWeight {
-	fn weight(&self, len: usize) -> Weight {
-		match self {
-			TransactionWeight::Basic(base, byte) => base + byte * len as Weight,
-			TransactionWeight::Max => 3 * 1024 * 1024,
-			TransactionWeight::Free => 0,
+impl From<SimpleDispatchInfo> for DispatchClass {
+	fn from(tx: SimpleDispatchInfo) -> Self {
+		match tx {
+			SimpleDispatchInfo::FixedOperational(_) => DispatchClass::Operational,
+			SimpleDispatchInfo::MaxOperational => DispatchClass::Operational,
+			SimpleDispatchInfo::FreeOperational => DispatchClass::Operational,
+
+			SimpleDispatchInfo::FixedNormal(_) => DispatchClass::Normal,
+			SimpleDispatchInfo::MaxNormal => DispatchClass::Normal,
+			SimpleDispatchInfo::FreeNormal => DispatchClass::Normal,
 		}
 	}
 }
 
-impl Default for TransactionWeight {
+/// A bundle of static information collected from the `#[weight = $x]` attributes.
+#[cfg_attr(feature = "std", derive(PartialEq, Eq, Debug))]
+#[derive(Clone, Copy, Default)]
+pub struct DispatchInfo {
+	/// Weight of this transaction.
+	pub weight: Weight,
+	/// Class of this transaction.
+	pub class: DispatchClass,
+}
+
+impl DispatchInfo {
+	/// Determine if this dispatch should pay the base length-related fee or not.
+	pub fn pay_length_fee(&self) -> bool {
+		match self.class {
+			DispatchClass::Normal => true,
+			// For now we assume all operational transactions don't pay the length fee.
+			DispatchClass::Operational => false,
+		}
+	}
+}
+
+/// A `Dispatchable` function (aka transaction) that can carry some static information along with it, using the
+/// `#[weight]` attribute.
+pub trait GetDispatchInfo {
+	/// Return a `DispatchInfo`, containing relevant information of this dispatch.
+	///
+	/// This is done independently of its encoded size.
+	fn get_dispatch_info(&self) -> DispatchInfo;
+}
+
+/// Means of weighing some particular kind of data (`T`).
+pub trait WeighData<T> {
+	/// Weigh the data `T` given by `target`.
+	fn weigh_data(&self, target: T) -> Weight;
+}
+
+/// Means of classifying a dispatchable function.
+pub trait ClassifyDispatch<T> {
+	/// Classify the dispatch function based on input data `target` of type `T`.
+	fn classify_dispatch(&self, target: T) -> DispatchClass;
+}
+
+/// Default type used with the `#[weight = x]` attribute in a substrate chain.
+///
+/// A user may pass in any other type that implements the correct traits. If not, the `Default`
+/// implementation of [`SimpleDispatchInfo`] is used.
+///
+/// For each generalized group (`Normal` and `Operation`):
+///   - A `Fixed` variant means weight fee is charged normally and the weight is the number
+///      specified in the inner value of the variant.
+///   - A `Free` variant is equal to `::Fixed(0)`. Note that this does not guarantee inclusion.
+///   - A `Max` variant is equal to `::Fixed(Weight::max_value())`.
+///
+/// Based on the final weight value, based on the above variants:
+///   - A _weight-fee_  is deducted.
+///   - The block weight is consumed proportionally.
+///
+/// As for the generalized groups themselves:
+///   - `Normal` variants will be assigned a priority proportional to their weight. They can only
+///     consume a portion (1/4) of the maximum block resource limits.
+///   - `Operational` variants will be assigned the maximum priority. They can potentially consume
+///     the entire block resource limit.
+#[derive(Clone, Copy)]
+pub enum SimpleDispatchInfo {
+	/// A normal dispatch with fixed weight.
+	FixedNormal(Weight),
+	/// A normal dispatch with the maximum weight.
+	MaxNormal,
+	/// A normal dispatch with no weight.
+	FreeNormal,
+	/// An operational dispatch with fixed weight.
+	FixedOperational(Weight),
+	/// An operational dispatch with the maximum weight.
+	MaxOperational,
+	/// An operational dispatch with no weight.
+	FreeOperational,
+}
+
+impl<T> WeighData<T> for SimpleDispatchInfo {
+	fn weigh_data(&self, _: T) -> Weight {
+		match self {
+			SimpleDispatchInfo::FixedNormal(w) => *w,
+			SimpleDispatchInfo::MaxNormal => Bounded::max_value(),
+			SimpleDispatchInfo::FreeNormal => Bounded::min_value(),
+
+			SimpleDispatchInfo::FixedOperational(w) => *w,
+			SimpleDispatchInfo::MaxOperational => Bounded::max_value(),
+			SimpleDispatchInfo::FreeOperational => Bounded::min_value(),
+		}
+	}
+}
+
+impl<T> ClassifyDispatch<T> for SimpleDispatchInfo {
+	fn classify_dispatch(&self, _: T) -> DispatchClass {
+		DispatchClass::from(*self)
+	}
+}
+
+impl Default for SimpleDispatchInfo {
 	fn default() -> Self {
-		// This implies that the weight is currently equal to tx-size, nothing more
+		// This implies that the weight is currently equal to 100, nothing more
 		// for all substrate transactions that do NOT explicitly annotate weight.
 		// TODO #2431 needs to be updated with proper max values.
-		TransactionWeight::Basic(0, 1)
+		SimpleDispatchInfo::FixedNormal(100)
 	}
 }