Adding benchmarking for new frame_election_provider_support (#11149)

* First stab at adding benchmarking for
`election-provider-support` onchain

* Adding `BoundedPhragMMS` and fixing stuff

* Fixing node runtime

* Fixing tests

* Finalising all benchmarking stuff

* better comments

* Better benchmarking config

* Better `WeightInfo` and benchmarking

* Fixing tests

* Adding some documentation

* Fixing some typos

* Incorporating review feedback

* cleanup of rustdocs

* rustdoc changes

* changes after code review

* Fixing some errors.

* Fixing dependencies post merge

* Bringing back `UnboundedExecution`

* Better rustdoc and naming

* Cargo.toml formatting

substrate/frame/election-provider-support/src/lib.rs

@@ -170,7 +170,7 @@ pub mod onchain;
 pub mod traits;
 #[cfg(feature = "std")]
 use codec::{Decode, Encode};
-use frame_support::{BoundedVec, RuntimeDebug};
+use frame_support::{weights::Weight, BoundedVec, RuntimeDebug};
 use sp_runtime::traits::Bounded;
 use sp_std::{fmt::Debug, prelude::*};
 
@@ -195,6 +195,9 @@ pub use sp_arithmetic;
 #[doc(hidden)]
 pub use sp_std;
 
+pub mod weights;
+pub use weights::WeightInfo;
+
 #[cfg(test)]
 mod mock;
 #[cfg(test)]
@@ -523,6 +526,12 @@ pub trait NposSolver {
 		targets: Vec<Self::AccountId>,
 		voters: Vec<(Self::AccountId, VoteWeight, impl IntoIterator<Item = Self::AccountId>)>,
 	) -> Result<ElectionResult<Self::AccountId, Self::Accuracy>, Self::Error>;
+
+	/// Measure the weight used in the calculation of the solver.
+	/// - `voters` is the number of voters.
+	/// - `targets` is the number of targets.
+	/// - `vote_degree` is the degree ie the maximum numbers of votes per voter.
+	fn weight<T: WeightInfo>(voters: u32, targets: u32, vote_degree: u32) -> Weight;
 }
 
 /// A wrapper for [`sp_npos_elections::seq_phragmen`] that implements [`NposSolver`]. See the
@@ -547,6 +556,10 @@ impl<
 	) -> Result<ElectionResult<Self::AccountId, Self::Accuracy>, Self::Error> {
 		sp_npos_elections::seq_phragmen(winners, targets, voters, Balancing::get())
 	}
+
+	fn weight<T: WeightInfo>(voters: u32, targets: u32, vote_degree: u32) -> Weight {
+		T::phragmen(voters, targets, vote_degree)
+	}
 }
 
 /// A wrapper for [`sp_npos_elections::phragmms()`] that implements [`NposSolver`]. See the
@@ -571,6 +584,10 @@ impl<
 	) -> Result<ElectionResult<Self::AccountId, Self::Accuracy>, Self::Error> {
 		sp_npos_elections::phragmms(winners, targets, voters, Balancing::get())
 	}
+
+	fn weight<T: WeightInfo>(voters: u32, targets: u32, vote_degree: u32) -> Weight {
+		T::phragmms(voters, targets, vote_degree)
+	}
 }
 
 /// A voter, at the level of abstraction of this crate.