pallet进阶(12)-benchmarking

2022-09-07

Word count: 1.5k | Reading time≈ 7 min

benchmarking应该都很熟悉，性能测试，同时该测试可以为pallet的公共方法提供权重值

1. 概述

编写benchmarking分两种情况：
1. 对函数进行性能测试时需要的构造条件不会涉及到本pallet以外的其它pallet；
2. 在对函数进行性能测试时需要先使用其它的pallet构造测试的先决条件。

2. 编写pallet业务代码

在lib.rs中：

#![cfg_attr(not(feature = "std"), no_std)]

#[cfg(test)]
mod mock;

#[cfg(feature = "runtime-benchmarks")]
mod benchmarking;

pub mod weights;
pub use weights::WeightInfo;

pub use pallet::*;
#[frame_support::pallet]
pub mod pallet {
	use codec::Codec;
	use frame_support::{
		pallet_prelude::*, sp_runtime::traits::AtLeast32BitUnsigned, sp_std::fmt::Debug,
	};
	use frame_system::pallet_prelude::*;
	use scale_info::prelude::vec::Vec;

	use crate::WeightInfo;
	use sp_io::hashing::{blake2_128, twox_128};

	#[pallet::pallet]
	#[pallet::generate_store(pub(super) trait Store)]
	pub struct Pallet<T>(_);

	#[pallet::config]
	pub trait Config: frame_system::Config {
		type Event: From<Event<Self>> + IsType<<Self as frame_system::Config>::Event>;

		//声明StudentNumber类型
		type StudentNumberType: Member
			+ Parameter
			+ AtLeast32BitUnsigned
			+ Codec
			+ From<u32>
			+ Into<u32>
			+ Copy
			+ Debug
			+ Default
			+ MaxEncodedLen
			+ MaybeSerializeDeserialize;

		//声明StudentName类型
		type StudentNameType: Parameter
			+ Member
			+ AtLeast32BitUnsigned
			+ Codec
			+ Default
			+ From<u128>
			+ Into<u128>
			+ Copy
			+ MaxEncodedLen
			+ MaybeSerializeDeserialize
			+ Debug;

		type WeightInfo: WeightInfo;
	}

	// 4. Runtime Storage
	// 用storageMap存储学生信息，（key， value）分别对应的是学号和姓名.
	#[pallet::storage]
	#[pallet::getter(fn students_info)]
	pub type StudentsInfo<T: Config> =
		StorageMap<_, Blake2_128Concat, T::StudentNumberType, T::StudentNameType, ValueQuery>;
   
	#[pallet::event]
	#[pallet::generate_deposit(pub(super) fn deposit_event)]
	pub enum Event<T: Config> {
		SetStudentInfo(T::StudentNumberType, T::StudentNameType),
	}
   
	#[pallet::error]
	pub enum Error<T> {
		// 相同学号的只允许设置一次名字
		SetStudentsInfoDuplicate,
	}

	#[pallet::call]
	impl<T: Config> Pallet<T> {
		#[pallet::weight(<T as Config>::WeightInfo::set_student_info((*student_number).into() ))]
		pub fn set_student_info(origin: OriginFor<T>, student_number: T::StudentNumberType, student_name: T::StudentNameType, ) -> DispatchResultWithPostInfo {
			ensure_signed(origin)?;
			if StudentsInfo::<T>::contains_key(student_number) {
				return Err(Error::<T>::SetStudentsInfoDuplicate.into())
			}
			StudentsInfo::<T>::insert(&student_number, &student_name);
			Self::deposit_event(Event::SetStudentInfo(student_number, student_name));
			Self::generate_key();
			Ok(().into())
		}
	}

	impl<T: Config> Pallet<T> {
		fn generate_key() {
			// let key1 = twox_128(b"Balances".to_vec().as_slice());
			let key1 = twox_128(b"Balances");
			let key2 = twox_128(b"FreeBalance");
			let key3 = Self::blake2_128_concat(
				b"0xd43593c715fdd31c61141abd04a99fd6822c8558854ccde39a5684e7a56da27d",
			);
			log::info!(target: "use-benchmarking", "------------ ============================, key1 = {:?}, key2 = {:?}, key3 = {:?}", key1, key2, key3);
			let a = "5GrwvaEF5zXb26Fz9rcQpDWS57CtERHpNehXCPcNoHGKutQY".as_bytes().to_vec();
			a.using_encoded(|ref slice| {
				log::info!(target: "use-benchmarking", "------------ ============================, code = {:?}", slice);
			});
		}

		fn blake2_128_concat(d: &[u8]) -> Vec<u8> {
			let mut v = blake2_128(d).to_vec();
			v.extend_from_slice(d);
			v
		}
	}
}

3. 编写mock代码

mock.rs

use crate as pallet_use_benchmarking;

use frame_support::traits::{ConstU16, ConstU64};
use frame_system as system;
use sp_core::H256;
use sp_runtime::{
	testing::Header,
	traits::{BlakeTwo256, IdentityLookup},
};

type UncheckedExtrinsic = frame_system::mocking::MockUncheckedExtrinsic<Test>;
type Block = frame_system::mocking::MockBlock<Test>;

frame_support::construct_runtime!(
	pub enum Test where
		Block = Block,
		NodeBlock = Block,
		UncheckedExtrinsic = UncheckedExtrinsic,
	{
		System: frame_system,
		UseBenchmarkingDemo: pallet_use_benchmarking,
	}
);

impl system::Config for Test {
	type BaseCallFilter = frame_support::traits::Everything;
	type BlockWeights = ();
	type BlockLength = ();
	type DbWeight = ();
	type Origin = Origin;
	type Call = Call;
	type Index = u64;
	type BlockNumber = u64;
	type Hash = H256;
	type Hashing = BlakeTwo256;
	type AccountId = u64;
	type Lookup = IdentityLookup<Self::AccountId>;
	type Header = Header;
	type Event = Event;
	type BlockHashCount = ConstU64<250>;
	type Version = ();
	type PalletInfo = PalletInfo;
	type AccountData = ();
	type OnNewAccount = ();
	type OnKilledAccount = ();
	type SystemWeightInfo = ();
	type SS58Prefix = ConstU16<42>;
	type OnSetCode = ();
	type MaxConsumers = frame_support::traits::ConstU32<16>;
}

impl pallet_use_benchmarking::Config for Test {
	type Event = Event;
	type StudentNumberType = u32;
	type StudentNameType = u128;
}

pub use frame_support::pallet_prelude::GenesisBuild;

pub fn new_test_ext() -> sp_io::TestExternalities {
	system::GenesisConfig::default().build_storage::<Test>().unwrap().into()
}

4. 编写benchmarking

编写benchmarking的目的主要是为调度函数生成对应的权重计算函数，对应到本例子中就主要是use-benchmarking的set_student_info函数生成对应的权重计算函数。
编写benchmark以宏benchmarks!包含，里面的内容主要分三部分，做的事情分别是准备条件、调用调度函数、对执行结果验证。对于第一步，其实就是对我们调度函数中的变量进行赋值，
benchmarking.rs

use super::*;

#[allow(unused)]
use crate::Pallet as UseBenchmarkingDemo;
use frame_benchmarking::{benchmarks, whitelisted_caller};
use frame_system::RawOrigin;

benchmarks! {
	set_student_info {
		let s in 0 .. 100;
		let caller: T::AccountId = whitelisted_caller();
	}:{
		let _ = UseBenchmarkingDemo::<T>::set_student_info(RawOrigin::Signed(caller).into(), s.into(), Default::default());
	}
	verify {
		assert_eq!(<StudentsInfo<T>>::get::<<T as pallet::Config>::StudentNumberType>(s.into()), Default::default());
	}

	impl_benchmark_test_suite!(UseBenchmarkingDemo, crate::mock::new_test_ext(), crate::mock::Test);
}

5. 添加到runtime中

添加依赖.pallet/runtime/Cargo.toml：

[dependencies]
#...
pallet-use-benchmarking = { version = "4.0.0-dev", default-features = false, path = "../pallets/use-benchmarking" }
#...

[features]
default = ["std"]
std = [
  #...
  "pallet-use-benchmarking/std",
  #...
]

runtime-benchmarks = [
  #...
  "pallet-use-benchmarking/runtime-benchmarks",
  #...
]

然后就是将use-benchmarking添加到runtime中，在runtime/src/lib.rs：

impl pallet_use_benchmarking::Config for Runtime {
  type Event = Event;
  type StudentNumberType = u32;
  type StudentNameType = u128;
}

construct_runtime!(
  pub enum Runtime where
    Block = Block,
    NodeBlock = opaque::Block,
    UncheckedExtrinsic = UncheckedExtrinsic
  {
    //...
    //添加下面这行
    UseBenchmarkingDemo: pallet_use_benchmarking,
  }
);

将use-benchmarking pallet添加到对应的benchmark宏中，在runtime/src/lib.rs：


#[cfg(feature = "runtime-benchmarks")]
mod benches {
  define_benchmarks!(
     //...
    //这行为添加的代码
    [pallet_use_benchmarking, UseBenchmarkingDemo]
  );
}

6. 编译&生成weights.rs文件

编译

1 2	# 需要带上--features runtime-benchmarks cargo build --features runtime-benchmarks

拷贝模板：

mkdir .maintain
cd .maintain
#此处的substrate同官方的repo仓库
#从substrate的repo中拷贝模板放到我们的substrate-node-template目录下
cp substrate/.maintain/frame-weight-template.hbs .

生成weights文件

./target/debug/node-template benchmark --chain dev \
  --execution wasm --wasm-execution compiled \
  --pallet pallet_use_benchmarking \
  --extrinsic "*" --steps 20 --repeat 10 \
  --output ./pallets/use-benchmarking/src/weights.rs \
  --template ./.maintain/frame-weight-template.hbs

执行完后就会在./pallets/use-benchmarking/src/目录下生成对应的weights.rs文件。
至此，生成了weights.rs文件，但是这仅仅只是生成，还需要把生成的权重函数用到pallet中

7. 将生成的权重函数应用到pallet中

首先需要在pallet的Cargo.toml中添加如下：


...
[dependencies]
...
#添加下面这行
sp-std = { default-features = false, 
  version = "4.0.0", 
  git = "https://github.com/paritytech/substrate.git", 
  branch = "polkadot-v0.9.28" }

[features]
default = ["std"]
std = [
  ...
  #添加下面这行
  "sp-std/std",
]

接着在pallet的lib.rs中：
将#[pallet::weight(100)]改为#[pallet::weight(<T as Config>::WeightInfo::set_student_info((*student_number).into() ))]
最后，还需要回到runtime/src/lib.rs文件，修改pallet_use_benchmarking的配置，如下：

impl pallet_use_benchmarking::Config for Runtime {
  //...
  //添加这一行
  type WeightInfo = pallet_use_benchmarking::weights::SubstrateWeight<Runtime>;
}

重新编译，pallet的对应的权重就会在新的执行文件中生效：

1	cargo build

8. 总结

本文编辑完毕