Struct mz_txn_wal::txn_read::DataSnapshot

pub struct DataSnapshot<T> {
    pub(crate) data_id: ShardId,
    pub(crate) latest_write: Option<T>,
    pub(crate) as_of: T,
    pub(crate) empty_to: T,
}

A token exchangeable for a data shard snapshot.

• Invariant: latest_write <= as_of < empty_to
• Invariant: (latest_write, empty_to) and (as_of, empty_to) have no unapplied writes (which means we can do an empty CaA of those times if we like).

Fields

data_id: ShardId

The id of the data shard this snapshot is for.

latest_write: Option<T>

The latest possibly unapplied write <= as_of. None if there are no writes via txns or if they’re all known to be applied.

as_of: T

The as_of asked for.

empty_to: T

Some timestamp s.t. [as_of, empty_to) is known to be empty of unapplied writes via txns.

Implementations

impl<T: Timestamp + Lattice + TotalOrder + Codec64 + Sync> DataSnapshot<T>

pub(crate) async fn unblock_read<K, V, D>( &self, data_write: WriteHandle<K, V, T, D>, )

where K: Debug + Codec, V: Debug + Codec, D: Debug + Semigroup + Ord + Codec64 + Send + Sync,

Unblocks reading a snapshot at self.as_of by waiting for the latest write before that time and then running an empty CaA if necessary.

pub async fn snapshot_and_fetch<K, V, D>( &self, data_read: &mut ReadHandle<K, V, T, D>, ) -> Result<Vec<((Result<K, String>, Result<V, String>), T, D)>, Since<T>>

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Debug + Semigroup + Ord + Codec64 + Send + Sync,

See ReadHandle::snapshot_and_fetch.

pub async fn snapshot_cursor<K, V, D>( &self, data_read: &mut ReadHandle<K, V, T, D>, should_fetch_part: impl for<'a> Fn(Option<&'a LazyPartStats>) -> bool, ) -> Result<Cursor<K, V, T, D>, Since<T>>

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Debug + Semigroup + Ord + Codec64 + Send + Sync,

See ReadHandle::snapshot_cursor.

pub async fn snapshot_and_stream<K, V, D>( &self, data_read: &mut ReadHandle<K, V, T, D>, ) -> Result<impl Stream<Item = ((Result<K, String>, Result<V, String>), T, D)>, Since<T>>

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Debug + Semigroup + Ord + Codec64 + Send + Sync,

See ReadHandle::snapshot_and_stream.

pub fn snapshot_stats_from_critical<K, V, D, O>( &self, data_since: &SinceHandle<K, V, T, D, O>, ) -> impl Future<Output = Result<SnapshotStats, Since<T>>> + Send + 'static

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Semigroup + Codec64 + Send + Sync, O: Opaque + Codec64,

See SinceHandle::snapshot_stats.

pub fn snapshot_stats_from_leased<K, V, D>( &self, data_since: &ReadHandle<K, V, T, D>, ) -> impl Future<Output = Result<SnapshotStats, Since<T>>> + Send + 'static

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Ord + Semigroup + Codec64 + Send + Sync,

See ReadHandle::snapshot_stats.

pub async fn snapshot_parts_stats<K, V, D>( &self, data_read: &ReadHandle<K, V, T, D>, ) -> Result<SnapshotPartsStats, Since<T>>

where K: Debug + Codec + Ord, V: Debug + Codec + Ord, D: Debug + Semigroup + Ord + Codec64 + Send + Sync,

See ReadHandle::snapshot_parts_stats.

pub(crate) fn validate(&self) -> Result<(), String>

Trait Implementations

impl<T: Debug> Debug for DataSnapshot<T>

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

Formats the value using the given formatter.