Struct mz_adapter::coord::read_policy::ReadHolds

pub struct ReadHolds<T: TimelyTimestamp> {
    pub storage_holds: BTreeMap<GlobalId, ReadHold<T>>,
    pub compute_holds: BTreeMap<(ComputeInstanceId, GlobalId), ReadHold<T>>,
}

Read holds kept to ensure a set of collections remains readable at some time.

This is a collection of ReadHold objects, which act as tokens ensuring that read frontiers cannot advance past the held time as long as they exist. Dropping a ReadHolds also drops the ReadHold tokens within and relinquishes the associated read capabilities.

Fields

storage_holds: BTreeMap<GlobalId, ReadHold<T>>

compute_holds: BTreeMap<(ComputeInstanceId, GlobalId), ReadHold<T>>

Implementations

impl<T: TimelyTimestamp> ReadHolds<T>

pub fn new() -> Self

Return empty ReadHolds.

pub fn is_empty(&self) -> bool

pub fn storage_ids(&self) -> impl Iterator<Item = GlobalId> + '_

Return the IDs of the contained storage collections.

pub fn compute_ids( &self, ) -> impl Iterator<Item = (ComputeInstanceId, GlobalId)> + '_

Return the IDs of the contained compute collections.

pub fn id_bundle(&self) -> CollectionIdBundle

Return a CollectionIdBundle containing all the IDs in the ReadHolds.

pub fn downgrade(&mut self, time: T)

Downgrade the contained ReadHolds to the given time.

pub fn remove_storage_collection(&mut self, id: GlobalId)

pub fn remove_compute_collection( &mut self, instance_id: ComputeInstanceId, id: GlobalId, )

impl<T: TimelyTimestamp + Lattice> ReadHolds<T>

pub fn least_valid_read(&self) -> Antichain<T>

pub fn since(&self, desired_id: &GlobalId) -> Antichain<T>

Returns the frontier at which this ReadHolds is holding back the since of the collection identified by id. This does not mean that the overall since of the collection is what we report here. Only that it is at least held back to the reported frontier by this read hold.

This method is not meant to be fast, use wisely!

fn merge(&mut self, other: Self)

Merge the read holds in other into the contained read holds.

fn extend(&mut self, other: Self)

Extend the contained read holds with those in other.

Panics

In contrast to ReadHolds::merge, this method expects the collection IDs in self and other to be distinct and panics otherwise.

Trait Implementations

impl<T: Debug + TimelyTimestamp> Debug for ReadHolds<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: TimelyTimestamp> Default for ReadHolds<T>

fn default() -> Self

Returns the “default value” for a type.