id:sumim:20070612:p1 の続きで、こんどは結城さんの 結城浩のはてな日記 - サンタクロース問題を解く(Java) における Java 版を Squeak Smalltalk に。
Ruby と違って Java だと Smalltalk へ直訳っぽく…というのは無理みたいで、書いていていろいろと発見があって面白かったです。
Object subclass: #CyclicBarrier instanceVariableNames: 'waitingParties awaitingProcess numOfParties barrierAction' CyclicBarrier>>initialize waitingParties := SharedQueue new CyclicBarrier>>await | process | waitingParties size < (numOfParties - 1) ifTrue: [ process := Processor activeProcess. waitingParties nextPut: process. process wait] ifFalse: [ barrierAction value. numOfParties - 1 timesRepeat: [waitingParties next notify]] CyclicBarrier>>setParties: anInteger action: aBlock numOfParties := anInteger. barrierAction := aBlock CyclicBarrier class>>parties: numOfParties ^self parties: numOfParties action: [] CyclicBarrier class>>parties: numOfParties action: actionBlock ^self new setParties: numOfParties action: actionBlock; yourself
Process subclass: #Santa instanceVariableNames: 'readyAllElvesToWork readyAllReindeersToWork reindeerPlayBarrier elfPlayBarrier reindeerWorkBarrier elfWorkBarrier sema workers' classVariableNames: 'ElfNum ReindeerNum' Santa>>initialize readyAllElvesToWork := false. readyAllReindeersToWork := false. reindeerWorkBarrier := CyclicBarrier parties: ReindeerNum action: [self notifyAllReindeersAreReadyToWork]. elfWorkBarrier := CyclicBarrier parties: ElfNum action: [self notifyAllElvesAreReadyToWork]. reindeerPlayBarrier := CyclicBarrier parties: ReindeerNum + 1. elfPlayBarrier := CyclicBarrier parties: ElfNum + 1. sema := Semaphore new. Santa out flush Santa>>notifyAllElvesAreReadyToWork Santa out nextPut: 'All elves are ready to work!!'. readyAllElvesToWork := true. self notify Santa>>notifyAllReindeersAreReadyToWork Santa out nextPut: 'All reindeers are ready to work!!'. readyAllReindeersToWork := true. self notify Santa>>startAllWorkers | worker | workers := OrderedCollection new. (1 to: ReindeerNum) do: [:i | worker := Worker named: 'Reindeer No.', i printString workBarrier: reindeerWorkBarrier playBarrier: reindeerPlayBarrier. workers add: worker. worker resume ]. (1 to: ElfNum) do: [:i | worker := Worker named: 'Elf No.', i printString workBarrier: elfWorkBarrier playBarrier: elfPlayBarrier. workers add: worker. worker resume ] Santa>>run self startAllWorkers. [ [readyAllElvesToWork not and: [readyAllReindeersToWork not]] whileTrue: [ self wait ]. readyAllReindeersToWork ifTrue: [ readyAllReindeersToWork := false. reindeerPlayBarrier await ]. readyAllElvesToWork ifTrue: [ readyAllElvesToWork := false. elfPlayBarrier await ] ] repeat Santa>>workers ^workers Santa>>notify sema signal Santa>>wait sema wait Santa class instanceVariableNames: 'out' Santa class>>initialize ReindeerNum := 9. ElfNum := 3. out := SharedQueue new "Santa initialize" Santa class>>new | newProcess | newProcess _ super new. newProcess suspendedContext: [newProcess run. Processor terminateActive] asContext. newProcess priority: Processor activePriority. ^newProcess Santa class>>example | santa | World findATranscript: nil. Transcript clear. santa := Santa new. santa resume. (Delay forSeconds: 8) wait. santa workers do: [:wk | wk terminate]. santa terminate. Santa out size timesRepeat: [Transcript cr; show: Santa out next] "self example" Santa class>>out ^out
Process subclass: #Worker instanceVariableNames: 'workBarrier playBarrier sema' Worker>>setName: nameString workBarrier: wBarrier playBarrier: pBarrier self name: nameString. workBarrier := wBarrier. playBarrier := pBarrier. Santa out nextPut: self name, ' is born.' Worker>>play Santa out nextPut: self name, ' is waiting to play.'. playBarrier await. self randomSleep Worker>>work Santa out nextPut: self name, ' is waiting to work.'. workBarrier await. self randomSleep Worker>>randomSleep (Delay forMilliseconds: 1000 atRandom) wait Worker>>run [self work; play] repeat Worker>>notify sema signal Worker>>wait sema wait Worker>>initialize sema := Semaphore new Worker class>>named: nameString workBarrier: wBarrier playBarrier: pBarrier | newProcess | newProcess := self new. newProcess setName: nameString workBarrier: wBarrier playBarrier: pBarrier. newProcess suspendedContext: [newProcess run. Processor terminateActive] asContext. newProcess priority: Processor activePriority. ^newProcess
Squeak Smalltlak には CyclicBarrier のようなクラスを見つけられなかったので、自前でなんちゃって版を用意しました。あと、Java の Object#wait()、#notify() っぽいものも、Santa と Worker にはセマフォへの委譲でしつらえてあります（くだんの CyclicBarrier でもそれらを使っています）。加えて、Squeak のトランスクリプト（環境内の標準出力っぽい機構）は、排他的処理がちょっとおかしいみたいなので、Santa のクラスインスタンス変数 out に関連づけた a SharedQueue で代用しました。一定時間実行後、out の内容をトランスクリプトにはき出しています。
Santa example の出力例はこんな感じ。
Reindeer No.1 is born. Reindeer No.2 is born. Reindeer No.3 is born. Reindeer No.4 is born. Reindeer No.5 is born. Reindeer No.6 is born. Reindeer No.7 is born. Reindeer No.8 is born. Reindeer No.9 is born. Elf No.1 is born. Elf No.2 is born. Elf No.3 is born. Reindeer No.1 is waiting to work. Reindeer No.2 is waiting to work. Reindeer No.3 is waiting to work. Reindeer No.4 is waiting to work. Reindeer No.5 is waiting to work. Reindeer No.6 is waiting to work. Reindeer No.7 is waiting to work. Reindeer No.8 is waiting to work. Reindeer No.9 is waiting to work. All reindeers are ready to work!! Elf No.1 is waiting to work. Elf No.2 is waiting to work. Elf No.3 is waiting to work. All elves are ready to work!! Reindeer No.1 is waiting to play. Reindeer No.4 is waiting to play. Reindeer No.9 is waiting to play. Reindeer No.7 is waiting to play. Reindeer No.3 is waiting to play. Elf No.3 is waiting to play. Reindeer No.8 is waiting to play. Reindeer No.5 is waiting to play. Reindeer No.2 is waiting to play. Elf No.1 is waiting to play. Elf No.2 is waiting to play. Reindeer No.6 is waiting to play. Reindeer No.8 is waiting to work. Elf No.3 is waiting to work. Reindeer No.4 is waiting to work. Elf No.1 is waiting to work. Elf No.2 is waiting to work. All elves are ready to work!! Reindeer No.3 is waiting to work. Reindeer No.5 is waiting to work. Elf No.2 is waiting to play. Elf No.3 is waiting to play. Reindeer No.9 is waiting to work. Reindeer No.6 is waiting to work. Elf No.1 is waiting to play. Elf No.1 is waiting to work. Reindeer No.1 is waiting to work. Elf No.2 is waiting to work. Reindeer No.7 is waiting to work. Reindeer No.2 is waiting to work. All reindeers are ready to work!! ...
id:sumim:20070613:p2 に続く。
