Prefetch Input Queue

Prefetch Input Queue is a lightweight, thread-safe library built with Scala and Actor model for educational purposes. It is designed to improve the efficiency of programs operating in a producer-consumer pattern by prefetching/buffering the data from source systems and delivering it to consumers, all in a thread-safe manner.

Todo:

• Continuous prefetching / buffering
• Thread-safe
• Exponential backoff mechanism
• Configurability

Usage

First implement custom ItemSource:

import com.idj.ItemSource
import scala.util.Random

class MyRandomIntsSource() extends ItemSource[Int] {

  override def get(n: Int): Future[Seq[Int]] = {
    Future.successful {
      Seq.fill(n)(Random.nextInt())
    }
  }
}

Then configure, create and start PrefetchInputQueue:

import com.idj.{PrefetchInputQueueConfig, PrefetchInputQueue}

val source = new MyRandomIntsSource()
val config = PrefetchInputQueueConfig(
  name = "myInputQueue",
  maxQueueSize = 1000,
  maxConcurrency = 10,
  maxBatchSize = 20,
  maxBackoff = 5.seconds
)
val queue = PrefetchInputQueue.create(source, config)
queue.start()

Consume items from the queue, in sync or async fashion. In case when queue is empty result value is returned immediately and is also empty:

val items: Seq[Int] = queue.get(n = 100) // sync api
val itemsFuture: Future[Int] = queue.getAsync(n = 100) // async api

Stop prefetching/buffering:

queue.stop() // can be resumed by calling start() again

Configuration

Name	Description	Default
name	Name used for logging
maxQueueSize	Maximum number of items to prefetch/buffer
maxConcurrency	Maximum number of allowed concurrent fetch calls to item source
maxBatchSize	Maximum number of items to fetch in each call
maxBackoff	Maximum wait time used in backoff mechanism	1 second

License

MIT License

Copyright (c) 2023

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.