akka/akka-core

Source.actorRefWithAck for batch sending to stream

Open

#26,818 opened on Apr 26, 2019

View on GitHub
 (0 comments) (0 reactions) (0 assignees)Scala (3,547 forks)batch import
1 - triagedhelp wantedt:stream

Repository metrics

Stars
 (13,277 stars)
PR merge metrics
 (Avg merge 8d 19h) (10 merged PRs in 30d)

Description

https://github.com/akka/akka/pull/26633 added actorRefWithAck with 1-1 acks and no buffering (single element buffer).

We could also have a variant with a buffer and OverflowStrategy similar to ActorRefSource and SourceQueue.

Then we could also support batch sending into the stream by having having a function that evaluates if an ack should be sent back for a given element and thereby 1-1 acks are not needed. Could be ackMessage: Any => Option[Any], where the first Any is the incoming message and the second is optionally the ack message.

Then one can define a Source.actorRefWithAck with buffer size 100 and use it like:

ackMessage = n => if (n % 50 == 0) Some(n) else None

ref ! 1
ref ! 2
ref ! 3
...
ref ! 99
// wait for ack 50 if not already received
ref ! 100
ref ! 101
...
ref ! 149
// wait for ack 100 if not already received
...

Inspiration for jmh benchmark can be found in https://github.com/akka/akka/blob/master/akka-bench-jmh/src/main/scala/akka/remote/artery/SendQueueBenchmark.scala#L79

Contributor guide

Research direction
Study the existing `actorRefWithAck` implementation in Akka Streams (Source.actorRefWithAck) and understand the single element buffer and 1-1 ack model. Then design a new variant that adds a configurable buffer with OverflowStrategy and a function `ackMessage: Any => Option[Any]` that determines when to send an ack based on incoming elements. Look at ActorRefSource and SourceQueue for buffer and overflow patterns. Also review the SendQueueBenchmark for performance considerations.
Tech stack
scala
Domain
backendapi
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
ScalaAkka Streams
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40