Crate pallet_im_online

I’m online Pallet

If the local node is a validator (i.e. contains an authority key), this pallet gossips a heartbeat transaction with each new session. The heartbeat functions as a simple mechanism to signal that the node is online in the current era.

Received heartbeats are tracked for one era and reset with each new era. The pallet exposes two public functions to query if a heartbeat has been received in the current era or session.

The heartbeat is a signed transaction, which was signed using the session key and includes the recent best block number of the local validators chain. It is submitted as an Unsigned Transaction via off-chain workers.

• Config
• Call
• Pallet

Interface

Public Functions

• is_online - True if the validator sent a heartbeat in the current session.

Usage

use pallet_im_online::{self as im_online};

#[frame_support::pallet]
pub mod pallet {
	use super::*;
	use frame_support::pallet_prelude::*;
	use frame_system::pallet_prelude::*;

	#[pallet::pallet]
	pub struct Pallet<T>(_);

	#[pallet::config]
	pub trait Config: frame_system::Config + im_online::Config {}

	#[pallet::call]
	impl<T: Config> Pallet<T> {
		#[pallet::weight(0)]
		pub fn is_online(origin: OriginFor<T>, authority_index: u32) -> DispatchResult {
			let _sender = ensure_signed(origin)?;
			let _is_online = <im_online::Pallet<T>>::is_online(authority_index);
			Ok(())
		}
	}
}

Dependencies

This pallet depends on the Session pallet.

Re-exports

• pub use weights::WeightInfo;
• pub use pallet::*;

Modules

• benchmarking 🔒
  I’m Online pallet benchmarking.
• ed25519
• migration
  Storage migrations for the im-online pallet.
• pallet
  The pallet module in each FRAME pallet hosts the most important items needed to construct this pallet.
• sr25519
• weights
  Autogenerated weights for pallet_im_online

Structs

• Heartbeat
  Heartbeat which is sent/received.
• HeartbeatStatus 🔒
  Status of the offchain worker code.
• UnresponsivenessOffence
  An offence that is filed if a validator didn’t send a heartbeat message.

Enums

• OffchainErr 🔒
  Error which may occur while executing the off-chain code.

Constants

• DB_PREFIX 🔒
• INCLUDE_THRESHOLD 🔒
  How many blocks do we wait for heartbeat transaction to be included before sending another one.

Type Aliases

• AuthIndex
• IdentificationTuple
  A tuple of (ValidatorId, Identification) where Identification is the full identification of ValidatorId.
• OffchainResult 🔒
• ValidatorId
  A type for representing the validator id in a session.