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Rename CardinalityOne -> LastWriteWins (part of #85)
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niko
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Sep 14, 2019
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,104 @@ | ||
| //! Operator enforcing last-write-wins semantics for each eid. | ||
| use timely::dataflow::channels::pact::Pipeline; | ||
| use timely::dataflow::operators::aggregation::StateMachine; | ||
| use timely::dataflow::operators::{generic::operator::Operator, Map}; | ||
| use timely::dataflow::Scope; | ||
|
|
||
| use differential_dataflow::lattice::Lattice; | ||
| use differential_dataflow::operators::arrange::{Arrange, Arranged}; | ||
| use differential_dataflow::trace::{cursor::Cursor, BatchReader}; | ||
| use differential_dataflow::{AsCollection, Collection}; | ||
|
|
||
| use crate::{TraceValHandle, Value}; | ||
|
|
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| /// Provides the `last_write_wins` method. | ||
| pub trait LastWriteWins<S: Scope> { | ||
| /// Ensures that only a single value per eid exists within an | ||
| /// attribute, by retracting any previous values upon new | ||
| /// updates. Therefore this stream does not expect explicit | ||
| /// retractions. | ||
| fn last_write_wins(&self) -> Collection<S, (Value, Value), isize>; | ||
| } | ||
|
|
||
| impl<S> LastWriteWins<S> for Collection<S, (Value, Value), isize> | ||
| where | ||
| S: Scope, | ||
| S::Timestamp: Lattice + Ord, | ||
| { | ||
| fn last_write_wins(&self) -> Collection<S, (Value, Value), isize> { | ||
| use differential_dataflow::hashable::Hashable; | ||
|
|
||
| let arranged: Arranged<S, TraceValHandle<Value, Value, S::Timestamp, isize>> = | ||
| self.arrange(); | ||
|
|
||
| arranged | ||
| .stream | ||
| .unary(Pipeline, "AsCollection", move |_, _| { | ||
| move |input, output| { | ||
| input.for_each(|time, data| { | ||
| let mut session = output.session(&time); | ||
| for wrapper in data.iter() { | ||
| let batch = &wrapper; | ||
| let mut cursor = batch.cursor(); | ||
| while let Some(key) = cursor.get_key(batch) { | ||
| let mut tuples = Vec::new(); | ||
| while let Some(val) = cursor.get_val(batch) { | ||
| cursor.map_times(batch, |time, diff| { | ||
| tuples.push(( | ||
| (key.clone(), val.clone()), | ||
| time.clone(), | ||
| diff.clone(), | ||
| )); | ||
| }); | ||
| cursor.step_val(batch); | ||
| } | ||
|
|
||
| tuples.sort_by_key(|(_, ref t, _)| t.clone()); | ||
| session.give_iterator(tuples.drain(..)); | ||
|
|
||
| cursor.step_key(batch); | ||
| } | ||
| } | ||
| }); | ||
| } | ||
| }) | ||
| .map( | ||
| |((e, next_v), t, diff): ((Value, Value), S::Timestamp, isize)| { | ||
| (e, (next_v, t, diff)) | ||
| }, | ||
| ) | ||
| .state_machine( | ||
| |e, (next_v, t, diff), v| { | ||
| match v { | ||
| None => { | ||
| assert!( | ||
| diff > 0, | ||
| "Received a retraction of a new key on a LastWriteWins attribute" | ||
| ); | ||
| *v = Some(next_v.clone()); | ||
| (false, vec![((e.clone(), next_v), t, 1)]) | ||
| } | ||
| Some(old_v) => { | ||
| let old_v = old_v.clone(); | ||
| if diff > 0 { | ||
| *v = Some(next_v.clone()); | ||
| ( | ||
| false, | ||
| vec![ | ||
| ((e.clone(), old_v), t.clone(), -1), | ||
| ((e.clone(), next_v), t, 1), | ||
| ], | ||
| ) | ||
| } else { | ||
| // Retraction received. Can clean up state. | ||
| (true, vec![((e.clone(), old_v), t, -1)]) | ||
| } | ||
| } | ||
| } | ||
| }, | ||
| |e| e.hashed(), | ||
| ) | ||
| .as_collection() | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,105 +1,6 @@ | ||
| //! Extension traits for `Stream` implementing various | ||
| //! declarative-specific operators. | ||
| use timely::dataflow::channels::pact::Pipeline; | ||
| use timely::dataflow::operators::aggregation::StateMachine; | ||
| use timely::dataflow::operators::{generic::operator::Operator, Map}; | ||
| use timely::dataflow::Scope; | ||
| mod last_write_wins; | ||
|
|
||
| use differential_dataflow::lattice::Lattice; | ||
| use differential_dataflow::operators::arrange::{Arrange, Arranged}; | ||
| use differential_dataflow::trace::{cursor::Cursor, BatchReader}; | ||
| use differential_dataflow::{AsCollection, Collection}; | ||
|
|
||
| use crate::{TraceValHandle, Value}; | ||
|
|
||
| /// Provides the `cardinality_one` method. | ||
| pub trait CardinalityOne<S: Scope> { | ||
| /// Ensures that only a single value per eid exists within an | ||
| /// attribute, by retracting any previous values upon new | ||
| /// updates. Therefore this stream does not expect explicit | ||
| /// retractions. | ||
| fn cardinality_one(&self) -> Collection<S, (Value, Value), isize>; | ||
| } | ||
|
|
||
| impl<S> CardinalityOne<S> for Collection<S, (Value, Value), isize> | ||
| where | ||
| S: Scope, | ||
| S::Timestamp: Lattice + Ord, | ||
| { | ||
| fn cardinality_one(&self) -> Collection<S, (Value, Value), isize> { | ||
| use differential_dataflow::hashable::Hashable; | ||
|
|
||
| let arranged: Arranged<S, TraceValHandle<Value, Value, S::Timestamp, isize>> = | ||
| self.arrange(); | ||
|
|
||
| arranged | ||
| .stream | ||
| .unary(Pipeline, "AsCollection", move |_, _| { | ||
| move |input, output| { | ||
| input.for_each(|time, data| { | ||
| let mut session = output.session(&time); | ||
| for wrapper in data.iter() { | ||
| let batch = &wrapper; | ||
| let mut cursor = batch.cursor(); | ||
| while let Some(key) = cursor.get_key(batch) { | ||
| let mut tuples = Vec::new(); | ||
| while let Some(val) = cursor.get_val(batch) { | ||
| cursor.map_times(batch, |time, diff| { | ||
| tuples.push(( | ||
| (key.clone(), val.clone()), | ||
| time.clone(), | ||
| diff.clone(), | ||
| )); | ||
| }); | ||
| cursor.step_val(batch); | ||
| } | ||
|
|
||
| tuples.sort_by_key(|(_, ref t, _)| t.clone()); | ||
| session.give_iterator(tuples.drain(..)); | ||
|
|
||
| cursor.step_key(batch); | ||
| } | ||
| } | ||
| }); | ||
| } | ||
| }) | ||
| .map( | ||
| |((e, next_v), t, diff): ((Value, Value), S::Timestamp, isize)| { | ||
| (e, (next_v, t, diff)) | ||
| }, | ||
| ) | ||
| .state_machine( | ||
| |e, (next_v, t, diff), v| { | ||
| match v { | ||
| None => { | ||
| assert!( | ||
| diff > 0, | ||
| "Received a retraction of a new key on a CardinalityOne attribute" | ||
| ); | ||
| *v = Some(next_v.clone()); | ||
| (false, vec![((e.clone(), next_v), t, 1)]) | ||
| } | ||
| Some(old_v) => { | ||
| let old_v = old_v.clone(); | ||
| if diff > 0 { | ||
| *v = Some(next_v.clone()); | ||
| ( | ||
| false, | ||
| vec![ | ||
| ((e.clone(), old_v), t.clone(), -1), | ||
| ((e.clone(), next_v), t, 1), | ||
| ], | ||
| ) | ||
| } else { | ||
| // Retraction received. Can clean up state. | ||
| (true, vec![((e.clone(), old_v), t, -1)]) | ||
| } | ||
| } | ||
| } | ||
| }, | ||
| |e| e.hashed(), | ||
| ) | ||
| .as_collection() | ||
| } | ||
| } | ||
| pub use last_write_wins::LastWriteWins; |
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