Actors in Scala (1140) by Philipp Haller & Frank Sommers

Author:Philipp Haller & Frank Sommers
Language: eng
Format: epub
Tags: Scala
Publisher: Artima Press
Published: 2011-03-14T16:00:00+00:00

val crasher = actor { println("I'm (re-)born") var cnt = 0 loop { cnt += 1 react { case 'request => println("I try to service a request") if (cnt % 2 == 0) { println("sometimes I crash...") throw new Exception } case 'stop => exit() } } }

val client = actor { react { case 'start => for (_ <- 1 to 6) { crasher ! 'request } crasher ! 'stop } }

actor { self.trapExit = true link(crasher) client ! 'start keepAlive(crasher) }

Listing 6.5 - Using keepAlive to automatically restart a crashed actor.

def renderImages(url: String) { val imageInfos = scanForImageInfo(url) self.trapExit = true val dataFutures = for (info <- imageInfos) yield { val loader = link { react { case Download(info) => throw new Exception("no connection") reply(info.downloadImage()) }: Unit } loader !! Download(info) } var i = 0 loopWhile (i < imageInfos.size) { i += 1 val Input = dataFutures(i-1).inputChannel react { case Input ! (data @ ImageData(_)) => renderImage(data) case Exit(from, UncaughtException(_, Some(Download(info)), _, _, cause)) => println("Couldn't download image "+info+ " because of "+cause) } } }

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