Liam Aharon
12ce4f7d04
Closes https://github.com/paritytech/polkadot-sdk-docs/issues/55 - Changes 'current storage version' terminology to less ambiguous 'in-code storage version' (suggestion by @ggwpez) - Adds a new example pallet `pallet-example-single-block-migrations` - Adds a new reference doc to replace https://docs.substrate.io/maintain/runtime-upgrades/ (temporarily living in the pallet while we wait for developer hub PR to merge) - Adds documentation for the `storage_alias` macro - Improves `trait Hooks` docs - Improves `trait GetStorageVersion` docs - Update the suggested patterns for using `VersionedMigration`, so that version unchecked migrations are never exported - Prevents accidental usage of version unchecked migrations in runtimes https://github.com/paritytech/substrate/pull/14421#discussion_r1255467895 - Unversioned migration code is kept inside `mod version_unchecked`, versioned code is kept in `pub mod versioned` - It is necessary to use modules to limit visibility because the inner migration must be `pub`. See https://github.com/rust-lang/rust/issues/30905 and https://internals.rust-lang.org/t/lang-team-minutes-private-in-public-rules/4504/40 for more. ### todo - [x] move to reference docs to proper place within sdk-docs (now that https://github.com/paritytech/polkadot-sdk/pull/2102 is merged) - [x] prdoc --------- Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> Co-authored-by: Juan <juangirini@gmail.com> Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> Co-authored-by: command-bot <> Co-authored-by: gupnik <nikhilgupta.iitk@gmail.com>
System Module
The System module provides low-level access to core types and cross-cutting utilities. It acts as the base layer for other pallets to interact with the Substrate framework components.
Overview
The System module defines the core data types used in a Substrate runtime. It also provides several utility functions
(see Pallet) for other FRAME pallets.
In addition, it manages the storage items for extrinsics data, indexes, event records, and digest items, among other things that support the execution of the current block.
It also handles low-level tasks like depositing logs, basic set up and take down of temporary storage entries, and access to previous block hashes.
Interface
Dispatchable Functions
The System module does not implement any dispatchable functions.
Public Functions
See the Pallet struct for details of
publicly available functions.
Signed Extensions
The System module defines the following extensions:
- [
CheckWeight]: Checks the weight and length of the block and ensure that it does not exceed the limits. - [
CheckNonce]: Checks the nonce of the transaction. Contains a single payload of typeT::Nonce. - [
CheckEra]: Checks the era of the transaction. Contains a single payload of typeEra. - [
CheckGenesis]: Checks the provided genesis hash of the transaction. Must be a part of the signed payload of the transaction. - [
CheckSpecVersion]: Checks that the runtime version is the same as the one used to sign the transaction. - [
CheckTxVersion]: Checks that the transaction version is the same as the one used to sign the transaction.
Lookup the runtime aggregator file (e.g. node/runtime) to see the full list of signed extensions included in a chain.
Usage
Prerequisites
Import the System module and derive your module's configuration trait from the system trait.
Example - Get extrinsic count and parent hash for the current block
#[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 {}
#[pallet::pallet]
pub struct Pallet<T>(_);
#[pallet::call]
impl<T: Config> Pallet<T> {
#[pallet::weight(0)]
pub fn system_module_example(origin: OriginFor<T>) -> DispatchResult {
let _sender = ensure_signed(origin)?;
let _extrinsic_count = <system::Pallet<T>>::extrinsic_count();
let _parent_hash = <system::Pallet<T>>::parent_hash();
Ok(())
}
}
}
License: Apache-2.0