Add pruning to bechmarks & update weights. (#918)

* Insert headers in benchmarks.

* Fix benchmarks.

* Lower number of headers.

* Avoid hardcoding numbers.

* Update weights.

* cargo fmt --all

* Remove todo.

* Fix test.

* Address review comments.

* Fix borrowed value.

bridges/bin/rialto/runtime/src/lib.rs

@@ -409,16 +409,30 @@ impl pallet_session::Config for Runtime {
 }
 
 parameter_types! {
-	// This is a pretty unscientific cap.
-	//
-	// Note that once this is hit the pallet will essentially throttle incoming requests down to one
-	// call per block.
+	/// This is a pretty unscientific cap.
+	///
+	/// Note that once this is hit the pallet will essentially throttle incoming requests down to one
+	/// call per block.
 	pub const MaxRequests: u32 = 50;
+}
 
-	// Number of headers to keep.
-	//
-	// Assuming the worst case of every header being finalized, we will keep headers at least for a
-	// week.
+#[cfg(feature = "runtime-benchmarks")]
+parameter_types! {
+	/// Number of headers to keep in benchmarks.
+	///
+	/// In benchmarks we always populate with full number of `HeadersToKeep` to make sure that
+	/// pruning is taken into account.
+	///
+	/// Note: This is lower than regular value, to speed up benchmarking setup.
+	pub const HeadersToKeep: u32 = 1024;
+}
+
+#[cfg(not(feature = "runtime-benchmarks"))]
+parameter_types! {
+	/// Number of headers to keep.
+	///
+	/// Assuming the worst case of every header being finalized, we will keep headers at least for a
+	/// week.
 	pub const HeadersToKeep: u32 = 7 * bp_rialto::DAYS as u32;
 }