mergePrioritizedN

Merge multiple sources with priorities.

Fan-in operators

Signature

Source.mergePrioritizedNSource.mergePrioritizedN

Description

Merge multiple sources. Prefer sources depending on priorities if all sources have elements ready. If a subset of all sources have elements ready the relative priorities for those sources are used to prioritize. For example, when used with only three sources sourceA, sourceB and sourceC, the sourceA has a probability of (priorityOfA) / (priorityOfA + priorityOfB + priorityOfC) of being prioritized and similarly for the rest of the sources. The priorities for each source must be positive integers.

Example

Scala

copysourceimport org.apache.pekko.stream.scaladsl.{ Sink, Source }

val sourceA = Source(List(1, 2, 3, 4))
val sourceB = Source(List(10, 20, 30, 40))
val sourceC = Source(List(100, 200, 300, 400))

Source
  .mergePrioritizedN(List((sourceA, 9900), (sourceB, 99), (sourceC, 1)), eagerComplete = false)
  .runWith(Sink.foreach(println))
// prints e.g. 1, 100, 2, 3, 4, 10, 20, 30, 40, 200, 300, 400  since both sources have their first element ready and
// the left sourceA has higher priority - if both sources have elements ready, sourceA has a 99% chance of being picked next
// while sourceB has a 0.99% chance and sourceC has a 0.01% chance

Java

copysourceSource<Integer, NotUsed> sourceA = Source.from(Arrays.asList(1, 2, 3, 4));
Source<Integer, NotUsed> sourceB = Source.from(Arrays.asList(10, 20, 30, 40));
Source<Integer, NotUsed> sourceC = Source.from(Arrays.asList(100, 200, 300, 400));
List<Pair<Source<Integer, ?>, Integer>> sourcesAndPriorities =
    Arrays.asList(new Pair<>(sourceA, 9900), new Pair<>(sourceB, 99), new Pair<>(sourceC, 1));
Source.mergePrioritizedN(sourcesAndPriorities, false).runForeach(System.out::println, system);
// prints e.g. 1, 100, 2, 3, 4, 10, 20, 30, 40, 200, 300, 400  since both sources have their
// first element ready and
// the left sourceA has higher priority - if both sources have elements ready, sourceA has a 99%
// chance of being picked next
// while sourceB has a 0.99% chance and sourceC has a 0.01% chance

Reactive Streams semantics