Some benchmarks for phragmen (#2650)

* Add some benchmarks for phragmen

* Fix dep. import.

* Clean up with some macros.

* more details.

* Fix dual import.

* Remove wrong assertions.

* Add a few more.

substrate/srml/staking/src/phragmen.rs

@@ -107,29 +107,29 @@ pub fn elect<T: Trait + 'static, FV, FN, FS>(
 	// Candidates who have 0 stake => have no votes or all null-votes. Kick them out not.
 	let mut nominators: Vec<Nominator<T::AccountId>> = Vec::with_capacity(validator_iter.size_hint().0 + nominator_iter.size_hint().0);
 	let mut candidates = validator_iter.map(|(who, _)| {
-			let stash_balance = stash_of(&who);
-			(Candidate { who, ..Default::default() }, stash_balance)
-		})
-		.filter_map(|(mut c, s)| {
-			c.approval_stake += to_votes(s);
-			if c.approval_stake.is_zero() {
-				None
-			} else {
-				Some((c, s))
-			}
-		})
-		.enumerate()
-		.map(|(idx, (c, s))| {
-			nominators.push(Nominator {
-				who: c.who.clone(),
-				edges: vec![ Edge { who: c.who.clone(), candidate_index: idx, ..Default::default() }],
-				budget: to_votes(s),
-				load: Fraction::zero(),
-			});
-			c_idx_cache.insert(c.who.clone(), idx);
-			c
-		})
-		.collect::<Vec<Candidate<T::AccountId>>>();
+		let stash_balance = stash_of(&who);
+		(Candidate { who, ..Default::default() }, stash_balance)
+	})
+	.filter_map(|(mut c, s)| {
+		c.approval_stake += to_votes(s);
+		if c.approval_stake.is_zero() {
+			None
+		} else {
+			Some((c, s))
+		}
+	})
+	.enumerate()
+	.map(|(idx, (c, s))| {
+		nominators.push(Nominator {
+			who: c.who.clone(),
+			edges: vec![ Edge { who: c.who.clone(), candidate_index: idx, ..Default::default() }],
+			budget: to_votes(s),
+			load: Fraction::zero(),
+		});
+		c_idx_cache.insert(c.who.clone(), idx);
+		c
+	})
+	.collect::<Vec<Candidate<T::AccountId>>>();
 
 	// 2- Collect the nominators with the associated votes.
 	// Also collect approval stake along the way.