Struct polkadot_node_subsystem_util::backing_implicit_view::View

pub struct View { /* private fields */ }

Handles the implicit view of the relay chain derived from the immediate view, which is composed of active leaves, and the minimum relay-parents allowed for candidates of various parachains at those leaves.

Implementations

impl View

pub fn leaves(&self) -> impl Iterator<Item = &Hash>

Get an iterator over active leaves in the view.

pub async fn activate_leaf<Sender>( &mut self, sender: &mut Sender, leaf_hash: Hash ) -> Result<Vec<ParaId>, FetchError>where Sender: SubsystemSender<ChainApiMessage> + SubsystemSender<ProspectiveParachainsMessage>,

Activate a leaf in the view. This will request the minimum relay parents from the Prospective Parachains subsystem for each leaf and will load headers in the ancestry of each leaf in the view as needed. These are the ‘implicit ancestors’ of the leaf.

To maximize reuse of outdated leaves, it’s best to activate new leaves before deactivating old ones.

This returns a list of para-ids which are relevant to the leaf, and the allowed relay parents for these paras under this leaf can be queried with View::known_allowed_relay_parents_under.

No-op for known leaves.

pub fn deactivate_leaf(&mut self, leaf_hash: Hash) -> Vec<Hash>

Deactivate a leaf in the view. This prunes any outdated implicit ancestors as well.

Returns hashes of blocks pruned from storage.

pub fn all_allowed_relay_parents(&self) -> impl Iterator<Item = &Hash>

Get an iterator over all allowed relay-parents in the view with no particular order.

Important: not all blocks are guaranteed to be allowed for some leaves, it may happen that a block info is only kept in the view storage because of a retaining rule.

For getting relay-parents that are valid for parachain candidates use View::known_allowed_relay_parents_under.

pub fn known_allowed_relay_parents_under( &self, block_hash: &Hash, para_id: Option<ParaId> ) -> Option<&[Hash]>

Get the known, allowed relay-parents that are valid for parachain candidates which could be backed in a child of a given block for a given para ID.

This is expressed as a contiguous slice of relay-chain block hashes which may include the provided block hash itself.

If para_id is None, this returns all valid relay-parents across all paras for the leaf.

None indicates that the block hash isn’t part of the implicit view or that there are no known allowed relay parents.

This always returns Some for active leaves or for blocks that previously were active leaves.

This can return the empty slice, which indicates that no relay-parents are allowed for the para, e.g. if the para is not scheduled at the given block hash.

Trait Implementations

impl Clone for View

fn clone(&self) -> View

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for View

fn default() -> View

Returns the “default value” for a type.