pub enum ReadPolicy<T> {
    NoPolicy {
        initial_since: Antichain<T>,
    },
    ValidFrom(Antichain<T>),
    LagWriteFrontier(Arc<dyn Fn(AntichainRef<'_, T>) -> Antichain<T> + Send + Sync>),
    Multiple(Vec<ReadPolicy<T>>),
}
Expand description

Compaction policies for collections maintained by Controller.

NOTE(benesch): this might want to live somewhere besides the storage crate, because it is fundamental to both storage and compute.

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NoPolicy

Fields

§initial_since: Antichain<T>

No-one has yet requested a ReadPolicy from us, which means that we can still change the implied_capability/the collection since if we need to.

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ValidFrom(Antichain<T>)

Maintain the collection as valid from this frontier onward.

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LagWriteFrontier(Arc<dyn Fn(AntichainRef<'_, T>) -> Antichain<T> + Send + Sync>)

Maintain the collection as valid from a function of the write frontier.

This function will only be re-evaluated when the write frontier changes. If the intended behavior is to change in response to external signals, consider using the ValidFrom variant to manually pilot compaction.

The Arc makes the function cloneable.

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Multiple(Vec<ReadPolicy<T>>)

Allows one to express multiple read policies, taking the least of the resulting frontiers.

Implementations§

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impl<T> ReadPolicy<T>where T: Timestamp + TimestampManipulation,

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pub fn step_back() -> Self

Creates a read policy that lags the write frontier “by one”.

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impl ReadPolicy<Timestamp>

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pub fn lag_writes_by(lag: Timestamp, max_granularity: Timestamp) -> Self

Creates a read policy that lags the write frontier by the indicated amount, rounded down to (at most) the specified value. The rounding down is done to reduce the number of changes the capability undergoes.

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impl<T: Timestamp> ReadPolicy<T>

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pub fn frontier(&self, write_frontier: AntichainRef<'_, T>) -> Antichain<T>

Trait Implementations§

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impl<T: Clone> Clone for ReadPolicy<T>

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fn clone(&self) -> ReadPolicy<T>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T> Debug for ReadPolicy<T>where T: Debug,

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

Formats the value using the given formatter. Read more

Auto Trait Implementations§

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impl<T> !RefUnwindSafe for ReadPolicy<T>

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impl<T> Send for ReadPolicy<T>where T: Send,

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impl<T> Sync for ReadPolicy<T>where T: Sync,

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impl<T> Unpin for ReadPolicy<T>where T: Unpin,

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impl<T> !UnwindSafe for ReadPolicy<T>

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> DynClone for Twhere T: Clone,

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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromRef<T> for Twhere T: Clone,

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fn from_ref(input: &T) -> T

Converts to this type from a reference to the input type.
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impl<T> FutureExt for T

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fn with_context(self, otel_cx: Context) -> WithContext<Self>

Attaches the provided Context to this type, returning a WithContext wrapper. Read more
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fn with_current_context(self) -> WithContext<Self>

Attaches the current Context to this type, returning a WithContext wrapper. Read more
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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoRequest<T> for T

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fn into_request(self) -> Request<T>

Wrap the input message T in a tonic::Request
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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> ProgressEventTimestamp for Twhere T: Data + Debug + Any,

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fn as_any(&self) -> &(dyn Any + 'static)

Upcasts this ProgressEventTimestamp to Any. Read more
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fn type_name(&self) -> &'static str

Returns the name of the concrete type of this object. Read more
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impl<P, R> ProtoType<R> for Pwhere R: RustType<P>,

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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<T> Data for Twhere T: Clone + 'static,