Custom Benchmark Errors and Override (#9517)

* initial idea

* update benchmark test to frame v2

* fix some errors

* fixes for elec phrag

* fix tests

* update extrinsic time and docs

* fix import

* undo extra changes

* helper function

* wrong way

* Update frame/benchmarking/src/utils.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* doesnt need encode/decode

* fix benchmark return

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/frame/benchmarking/src/utils.rs

@@ -18,7 +18,11 @@
 //! Interfaces, types and utils for benchmarking a FRAME runtime.
 
 use codec::{Decode, Encode};
-use frame_support::traits::StorageInfo;
+use frame_support::{
+	dispatch::{DispatchError, DispatchErrorWithPostInfo},
+	pallet_prelude::*,
+	traits::StorageInfo,
+};
 use sp_io::hashing::blake2_256;
 use sp_std::{prelude::Box, vec::Vec};
 use sp_storage::TrackedStorageKey;
@@ -73,7 +77,7 @@ pub struct BenchmarkBatch {
 	/// The extrinsic (or benchmark name) of this benchmark.
 	pub benchmark: Vec<u8>,
 	/// The results from this benchmark.
-	pub results: Vec<BenchmarkResults>,
+	pub results: Vec<BenchmarkResult>,
 }
 
 // TODO: could probably make API cleaner here.
@@ -87,16 +91,16 @@ pub struct BenchmarkBatchSplitResults {
 	/// The extrinsic (or benchmark name) of this benchmark.
 	pub benchmark: Vec<u8>,
 	/// The extrinsic timing results from this benchmark.
-	pub time_results: Vec<BenchmarkResults>,
+	pub time_results: Vec<BenchmarkResult>,
 	/// The db tracking results from this benchmark.
-	pub db_results: Vec<BenchmarkResults>,
+	pub db_results: Vec<BenchmarkResult>,
 }
 
-/// Results from running benchmarks on a FRAME pallet.
+/// Result from running benchmarks on a FRAME pallet.
 /// Contains duration of the function call in nanoseconds along with the benchmark parameters
 /// used for that benchmark result.
 #[derive(Encode, Decode, Default, Clone, PartialEq, Debug)]
-pub struct BenchmarkResults {
+pub struct BenchmarkResult {
 	pub components: Vec<(BenchmarkParameter, u32)>,
 	pub extrinsic_time: u128,
 	pub storage_root_time: u128,
@@ -108,6 +112,50 @@ pub struct BenchmarkResults {
 	pub keys: Vec<(Vec<u8>, u32, u32, bool)>,
 }
 
+impl BenchmarkResult {
+	pub fn from_weight(w: Weight) -> Self {
+		Self { extrinsic_time: (w as u128) / 1_000, ..Default::default() }
+	}
+}
+
+/// Possible errors returned from the benchmarking pipeline.
+///
+/// * Stop: The benchmarking pipeline should stop and return the inner string.
+/// * WeightOverride: The benchmarking pipeline is allowed to fail here, and we should use the
+///   included weight instead.
+#[derive(Clone, PartialEq, Debug)]
+pub enum BenchmarkError {
+	Stop(&'static str),
+	Override(BenchmarkResult),
+}
+
+impl From<BenchmarkError> for &'static str {
+	fn from(e: BenchmarkError) -> Self {
+		match e {
+			BenchmarkError::Stop(s) => s,
+			BenchmarkError::Override(_) => "benchmark override",
+		}
+	}
+}
+
+impl From<&'static str> for BenchmarkError {
+	fn from(s: &'static str) -> Self {
+		Self::Stop(s)
+	}
+}
+
+impl From<DispatchErrorWithPostInfo> for BenchmarkError {
+	fn from(e: DispatchErrorWithPostInfo) -> Self {
+		Self::Stop(e.into())
+	}
+}
+
+impl From<DispatchError> for BenchmarkError {
+	fn from(e: DispatchError) -> Self {
+		Self::Stop(e.into())
+	}
+}
+
 /// Configuration used to setup and run runtime benchmarks.
 #[derive(Encode, Decode, Default, Clone, PartialEq, Debug)]
 pub struct BenchmarkConfig {
@@ -235,7 +283,7 @@ pub trait Benchmarking {
 }
 
 /// The pallet benchmarking trait.
-pub trait Benchmarking<T> {
+pub trait Benchmarking {
 	/// Get the benchmarks available for this pallet. Generally there is one benchmark per
 	/// extrinsic, so these are sometimes just called "extrinsics".
 	///
@@ -251,7 +299,7 @@ pub trait Benchmarking<T> {
 		whitelist: &[TrackedStorageKey],
 		verify: bool,
 		internal_repeats: u32,
-	) -> Result<Vec<T>, &'static str>;
+	) -> Result<Vec<BenchmarkResult>, BenchmarkError>;
 }
 
 /// The required setup for creating a benchmark.
@@ -267,7 +315,7 @@ pub trait BenchmarkingSetup<T, I = ()> {
 		&self,
 		components: &[(BenchmarkParameter, u32)],
 		verify: bool,
-	) -> Result<Box<dyn FnOnce() -> Result<(), &'static str>>, &'static str>;
+	) -> Result<Box<dyn FnOnce() -> Result<(), BenchmarkError>>, &'static str>;
 }
 
 /// Grab an account, seeded by a name and index.