Struct mz_persist_client::cache::StateCache

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pub struct StateCache {
    cfg: Arc<PersistConfig>,
    pub(crate) metrics: Arc<Metrics>,
    states: Arc<Mutex<BTreeMap<ShardId, Arc<OnceCell<Weak<dyn DynState>>>>>>,
    pubsub_sender: Arc<dyn PubSubSender>,
}
Expand description

A cache of TypedState, shared between all machines for that shard.

This is shared between all machines that come out of the same PersistClientCache, but in production there is one of those per process, so in practice, we have one copy of state per shard per process.

The mutex contention between commands is not an issue, because if two command for the same shard are executing concurrently, only one can win anyway, the other will retry. With the mutex, we even get to avoid the retry if the racing commands are on the same process.

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§cfg: Arc<PersistConfig>§metrics: Arc<Metrics>§states: Arc<Mutex<BTreeMap<ShardId, Arc<OnceCell<Weak<dyn DynState>>>>>>§pubsub_sender: Arc<dyn PubSubSender>

Implementations§

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impl StateCache

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pub fn new( cfg: &PersistConfig, metrics: Arc<Metrics>, pubsub_sender: Arc<dyn PubSubSender>, ) -> Self

Returns a new StateCache.

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pub(crate) async fn get<K, V, T, D, F, InitFn>( &self, shard_id: ShardId, init_fn: InitFn, diagnostics: &Diagnostics, ) -> Result<Arc<LockingTypedState<K, V, T, D>>, Box<CodecMismatch>>
where K: Debug + Codec, V: Debug + Codec, T: Timestamp + Lattice + Codec64, D: Semigroup + Codec64, F: Future<Output = Result<TypedState<K, V, T, D>, Box<CodecMismatch>>>, InitFn: FnMut() -> F,

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pub(crate) fn get_state_weak( &self, shard_id: &ShardId, ) -> Option<Weak<dyn DynState>>

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impl Debug for StateCache

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

Formats the value using the given formatter. Read more

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