Shared Pallet
This module is responsible for managing shared storage and configuration for other modules.
It is important that other pallets are able to use the Shared Module, so it should not have a dependency on any other modules in the Parachains Runtime.
For the moment, it is used exclusively to track the current session index across the Parachains Runtime system, and when it should be allowed to schedule future changes to Paras or Configurations.
Constants
Storage
Helper structs:
Storage Layout:
Initialization
The Shared Module currently has no initialization routines.
The Shared Module is initialized directly after the Configuration module, but before all other modules. It is important to update the Shared Module before any other module since its state may be used within the logic of other modules, and it is important that the state is consistent across them.
Session Change
During a session change, the Shared Module receives and stores the current Session Index directly from the initializer module, along with the broader validator set, and it returns the new list of validators.
The list of validators should be first shuffled according to the chain's random seed and then truncated. The indices of
these validators should be set to ActiveValidatorIndices
and then returned back to the initializer.
ActiveValidatorKeys
should be set accordingly.
This information is used in the:
- Configuration Module: For delaying updates to configurations until at lease one full session has passed.
- Paras Module: For delaying updates to paras until at least one full session has passed.
Allowed relay parents buffer, which is maintained by ParaInherent module, is cleared on every session change.
Finalization
The Shared Module currently has no finalization routines.
Functions
scheduled_sessions() -> SessionIndex
: Return the next session index where updates to the Parachains Runtime system would be safe to apply.set_session_index(SessionIndex)
: For tests. Set the current session index in the Shared Module.