Struct ComputeCommandHistory

pub struct ComputeCommandHistory<M, T = Timestamp> {
    reduced_count: usize,
    commands: Vec<ComputeCommand<T>>,
    metrics: HistoryMetrics<M>,
}

TODO(database-issues#7533): Add documentation.

Fields

reduced_count: usize

The number of commands at the last time we compacted the history.

commands: Vec<ComputeCommand<T>>

The sequence of commands that should be applied.

This list may not be “compact” in that there can be commands that could be optimized or removed given the context of other commands, for example compaction commands that can be unified, or dataflows that can be dropped due to allowed compaction.

metrics: HistoryMetrics<M>

Tracked metrics.

Implementations

impl<M, T> ComputeCommandHistory<M, T>

where M: Borrow<UIntGauge>, T: Timestamp,

pub fn new(metrics: HistoryMetrics<M>) -> Self

TODO(database-issues#7533): Add documentation.

pub fn push(&mut self, command: ComputeCommand<T>)

Add a command to the history.

This action will reduce the history every time it doubles.

pub fn reduce(&mut self)

Reduces self.history to a minimal form.

This action not only simplifies the issued history, but importantly reduces the instructions to only reference inputs from times that are still certain to be valid. Commands that allow compaction of a collection also remove certainty that the inputs will be available for times not greater or equal to that compaction frontier.

pub fn discard_peeks(&mut self)

Discard all peek commands.

pub fn update_source_uppers( &mut self, storage_collections: &Arc<dyn StorageCollections<Timestamp = T> + Send + Sync>, )

Update the source import uppers to reflect the current state of the imported collections.

This method should be called after compacting the history to make sure that the dataflow descriptions do not mention storage collections that don’t exist anymore. Its main purpose is to advance the uppers when connecting a new replica.

pub fn iter(&self) -> impl Iterator<Item = &ComputeCommand<T>>

Iterate through the contained commands.

Trait Implementations

impl<M: Debug, T: Debug> Debug for ComputeCommandHistory<M, T>

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

Formats the value using the given formatter.