Bastian Köcher
4af64eb071
* pallet-timestamp: Remove `ValidAtTimestamp` error variant The error variant wasn't that useful and it was also used wrongly in the code. In the code we returned this variant when the `timestamp < minimum`. The problem of this is that we waited on the node side some time, but then `set` function rejects the timestamp because of the same check (the timestamp in the block stays the same). We ensure that the timestamp isn't drifting too much in the future, but waiting for the timestamp to be "valid" would open some attack vector. The consensus protocols also compare the slots in the blocks to ensure that there isn't a block from the future and in the runtime we then ensure that `slot = timestamp / slot_duration`. So, we can just remove this variant and replace it with a new variant `TimeBetweenBlocksTooShort` to not even try importing a block which uses a too short delay since the last block. * Update primitives/timestamp/src/lib.rs Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com> * Rename to `TooEarly` * FMT --------- Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>
Timestamp Module
The Timestamp module provides functionality to get and set the on-chain time.
Overview
The Timestamp module allows the validators to set and validate a timestamp with each block.
It uses inherents for timestamp data, which is provided by the block author and validated/verified by other validators. The timestamp can be set only once per block and must be set each block. There could be a constraint on how much time must pass before setting the new timestamp.
NOTE: The Timestamp module is the recommended way to query the on-chain time instead of using an approach based on block numbers. The block number based time measurement can cause issues because of cumulative calculation errors and hence should be avoided.
Interface
Dispatchable Functions
set- Sets the current time.
Public functions
get- Gets the current time for the current block. If this function is called prior to setting the timestamp, it will return the timestamp of the previous block.
Config Getters
MinimumPeriod- Gets the minimum (and advised) period between blocks for the chain.
Usage
The following example shows how to use the Timestamp module in your custom module to query the current timestamp.
Prerequisites
Import the Timestamp module into your custom module and derive the module configuration trait from the timestamp trait.
Get current timestamp
use pallet_timestamp::{self as timestamp};
#[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 + timestamp::Config {}
#[pallet::call]
impl<T: Config> Pallet<T> {
#[pallet::weight(0)]
pub fn get_time(origin: OriginFor<T>) -> DispatchResult {
let _sender = ensure_signed(origin)?;
let _now = <timestamp::Pallet<T>>::get();
Ok(())
}
}
}
Example from the FRAME
The Session module uses the Timestamp module for session management.
Related Modules
License: Apache-2.0