mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-07-10 23:57:23 +00:00
Stanislav Tkach
97 lines
2.6 KiB
Rust
97 lines
2.6 KiB
Rust
// Copyright 2017 Parity Technologies (UK) Ltd.
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// This file is part of Polkadot.
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// Polkadot is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Polkadot is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
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//! Basic parachain that adds a number as part of its state.
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#![no_std]
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use parity_codec::{Encode, Decode};
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/// Head data for this parachain.
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#[derive(Default, Clone, Hash, Eq, PartialEq, Encode, Decode)]
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pub struct HeadData {
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/// Block number
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pub number: u64,
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/// parent block keccak256
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pub parent_hash: [u8; 32],
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/// hash of post-execution state.
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pub post_state: [u8; 32],
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}
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impl HeadData {
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pub fn hash(&self) -> [u8; 32] {
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::tiny_keccak::keccak256(&self.encode())
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}
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}
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/// Block data for this parachain.
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#[derive(Default, Clone, Encode, Decode)]
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pub struct BlockData {
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/// State to begin from.
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pub state: u64,
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/// Amount to add (overflowing)
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pub add: u64,
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}
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pub fn hash_state(state: u64) -> [u8; 32] {
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::tiny_keccak::keccak256(state.encode().as_slice())
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}
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#[derive(Default, Encode, Decode)]
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pub struct AddMessage {
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/// The amount to add based on this message.
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pub amount: u64,
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}
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/// Start state mismatched with parent header's state hash.
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#[derive(Debug)]
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pub struct StateMismatch;
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/// Process all incoming messages, yielding the amount of addition from messages.
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///
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/// Ignores unknown message kinds.
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pub fn process_messages<I, T>(iterable: I) -> u64
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where I: IntoIterator<Item=T>, T: AsRef<[u8]>
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{
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iterable.into_iter()
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.filter_map(|data| AddMessage::decode(&mut data.as_ref()))
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.fold(0u64, |a, c| a.overflowing_add(c.amount).0)
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}
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/// Execute a block body on top of given parent head, producing new parent head
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/// if valid.
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pub fn execute(
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parent_hash: [u8; 32],
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parent_head: HeadData,
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block_data: &BlockData,
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from_messages: u64,
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) -> Result<HeadData, StateMismatch> {
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debug_assert_eq!(parent_hash, parent_head.hash());
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if hash_state(block_data.state) != parent_head.post_state {
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return Err(StateMismatch);
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}
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let new_state = block_data.state.overflowing_add(block_data.add).0;
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let new_state = new_state.overflowing_add(from_messages).0;
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Ok(HeadData {
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number: parent_head.number + 1,
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parent_hash,
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post_state: hash_state(new_state),
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})
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}
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