Move all example pallets under examples folder. (#10215)

* Put all examples under one folder

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* Updated Cargo.toml

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* updated for ci script

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* update

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* Added notes that example pallets are not meant to be used in production.

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

* updated

Signed-off-by: Jimmy Chu <jimmychu0807@gmail.com>

substrate/frame/examples/parallel/src/lib.rs

@@ -0,0 +1,150 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020-2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! # Parallel Tasks Example Pallet
+//!
+//! This example pallet demonstrates parallelizing validation of the enlisted participants
+//! (see `enlist_participants` dispatch).
+//!
+//! **This pallet serves as an example and is not meant to be used in production.**
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+use sp_runtime::RuntimeDebug;
+
+use codec::{Decode, Encode};
+use sp_std::vec::Vec;
+
+#[cfg(test)]
+mod tests;
+
+pub use pallet::*;
+
+#[frame_support::pallet]
+pub mod pallet {
+	use super::*;
+	use frame_support::pallet_prelude::*;
+	use frame_system::pallet_prelude::*;
+
+	#[pallet::config]
+	pub trait Config: frame_system::Config {
+		/// The overarching dispatch call type.
+		type Call: From<Call<Self>>;
+	}
+
+	#[pallet::pallet]
+	#[pallet::generate_store(pub(super) trait Store)]
+	pub struct Pallet<T>(_);
+
+	/// A public part of the pallet.
+	#[pallet::call]
+	impl<T: Config> Pallet<T> {
+		/// Get the new event running.
+		#[pallet::weight(0)]
+		pub fn run_event(origin: OriginFor<T>, id: Vec<u8>) -> DispatchResultWithPostInfo {
+			let _ = ensure_signed(origin)?;
+			<Participants<T>>::kill();
+			<CurrentEventId<T>>::mutate(move |event_id| *event_id = id);
+			Ok(().into())
+		}
+
+		/// Submit list of participants to the current event.
+		///
+		/// The example utilizes parallel execution by checking half of the
+		/// signatures in spawned task.
+		#[pallet::weight(0)]
+		pub fn enlist_participants(
+			origin: OriginFor<T>,
+			participants: Vec<EnlistedParticipant>,
+		) -> DispatchResultWithPostInfo {
+			let _ = ensure_signed(origin)?;
+
+			if validate_participants_parallel(&<CurrentEventId<T>>::get(), &participants[..]) {
+				for participant in participants {
+					<Participants<T>>::append(participant.account);
+				}
+			}
+			Ok(().into())
+		}
+	}
+
+	/// A vector of current participants
+	///
+	/// To enlist someone to participate, signed payload should be
+	/// sent to `enlist`.
+	#[pallet::storage]
+	#[pallet::getter(fn participants)]
+	pub(super) type Participants<T: Config> = StorageValue<_, Vec<Vec<u8>>, ValueQuery>;
+
+	/// Current event id to enlist participants to.
+	#[pallet::storage]
+	#[pallet::getter(fn get_current_event_id)]
+	pub(super) type CurrentEventId<T: Config> = StorageValue<_, Vec<u8>, ValueQuery>;
+}
+
+/// Request to enlist participant.
+#[derive(Encode, Decode, Clone, PartialEq, Eq, RuntimeDebug, scale_info::TypeInfo)]
+pub struct EnlistedParticipant {
+	pub account: Vec<u8>,
+	pub signature: Vec<u8>,
+}
+
+impl EnlistedParticipant {
+	fn verify(&self, event_id: &[u8]) -> bool {
+		use sp_core::Public;
+		use sp_runtime::traits::Verify;
+
+		match sp_core::sr25519::Signature::try_from(&self.signature[..]) {
+			Ok(signature) => {
+				let public = sp_core::sr25519::Public::from_slice(self.account.as_ref());
+				signature.verify(event_id, &public)
+			},
+			_ => false,
+		}
+	}
+}
+
+fn validate_participants_parallel(event_id: &[u8], participants: &[EnlistedParticipant]) -> bool {
+	fn spawn_verify(data: Vec<u8>) -> Vec<u8> {
+		let stream = &mut &data[..];
+		let event_id = Vec::<u8>::decode(stream).expect("Failed to decode");
+		let participants = Vec::<EnlistedParticipant>::decode(stream).expect("Failed to decode");
+
+		for participant in participants {
+			if !participant.verify(&event_id) {
+				return false.encode()
+			}
+		}
+		true.encode()
+	}
+
+	let mut async_payload = Vec::new();
+	event_id.encode_to(&mut async_payload);
+	participants[..participants.len() / 2].encode_to(&mut async_payload);
+
+	let handle = sp_tasks::spawn(spawn_verify, async_payload);
+	let mut result = true;
+
+	for participant in &participants[participants.len() / 2 + 1..] {
+		if !participant.verify(event_id) {
+			result = false;
+			break
+		}
+	}
+
+	bool::decode(&mut &handle.join()[..]).expect("Failed to decode result") && result
+}