commit 83e6b4d4c6f7dd72558bedf2a1eddbf8fbfa4847 Author: Jakob Waibel Date: Fri Sep 23 05:06:34 2022 +0200 Add Dining Philosopher and Consumer Producer base code structure diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..796b96d --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +/build diff --git a/build.gradle.kts b/build.gradle.kts new file mode 100644 index 0000000..6aa0b31 --- /dev/null +++ b/build.gradle.kts @@ -0,0 +1,30 @@ +import org.jetbrains.kotlin.gradle.tasks.KotlinCompile + +plugins { + kotlin("jvm") version "1.7.10" +} + +group = "org.example" +version = "1.0-SNAPSHOT" + +repositories { + mavenCentral() +} + +dependencies { + implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.6.4") + implementation("io.kotest:kotest-runner-junit5-jvm:5.4.2") + testImplementation(kotlin("test")) + testImplementation("io.kotest:kotest-runner-junit5:5.4.2") + testImplementation("io.kotest:kotest-property:5.4.2") + testImplementation("org.jetbrains.kotlinx:kotlinx-coroutines-debug:1.4.0") +} + +tasks.test { + useJUnitPlatform() + testLogging.showStandardStreams = true +} + +tasks.withType { + kotlinOptions.jvmTarget = "1.8" +} diff --git a/gradle.properties b/gradle.properties new file mode 100644 index 0000000..7fc6f1f --- /dev/null +++ b/gradle.properties @@ -0,0 +1 @@ +kotlin.code.style=official diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar new file mode 100644 index 0000000..7454180 Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties new file mode 100644 index 0000000..60c76b3 --- /dev/null +++ b/gradle/wrapper/gradle-wrapper.properties @@ -0,0 +1,5 @@ +distributionBase=GRADLE_USER_HOME +distributionPath=wrapper/dists +distributionUrl=https\://services.gradle.org/distributions/gradle-7.4.2-bin.zip +zipStoreBase=GRADLE_USER_HOME +zipStorePath=wrapper/dists \ No newline at end of file diff --git a/gradlew b/gradlew new file mode 100755 index 0000000..1b6c787 --- /dev/null +++ b/gradlew @@ -0,0 +1,234 @@ +#!/bin/sh + +# +# Copyright © 2015-2021 the original authors. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# + +############################################################################## +# +# Gradle start up script for POSIX generated by Gradle. +# +# Important for running: +# +# (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is +# noncompliant, but you have some other compliant shell such as ksh or +# bash, then to run this script, type that shell name before the whole +# command line, like: +# +# ksh Gradle +# +# Busybox and similar reduced shells will NOT work, because this script +# requires all of these POSIX shell features: +# * functions; +# * expansions «$var», «${var}», «${var:-default}», «${var+SET}», +# «${var#prefix}», «${var%suffix}», and «$( cmd )»; +# * compound commands having a testable exit status, especially «case»; +# * various built-in commands including «command», «set», and «ulimit». +# +# Important for patching: +# +# (2) This script targets any POSIX shell, so it avoids extensions provided +# by Bash, Ksh, etc; in particular arrays are avoided. +# +# The "traditional" practice of packing multiple parameters into a +# space-separated string is a well documented source of bugs and security +# problems, so this is (mostly) avoided, by progressively accumulating +# options in "$@", and eventually passing that to Java. +# +# Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS, +# and GRADLE_OPTS) rely on word-splitting, this is performed explicitly; +# see the in-line comments for details. +# +# There are tweaks for specific operating systems such as AIX, CygWin, +# Darwin, MinGW, and NonStop. +# +# (3) This script is generated from the Groovy template +# https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt +# within the Gradle project. +# +# You can find Gradle at https://github.com/gradle/gradle/. +# +############################################################################## + +# Attempt to set APP_HOME + +# Resolve links: $0 may be a link +app_path=$0 + +# Need this for daisy-chained symlinks. +while + APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path + [ -h "$app_path" ] +do + ls=$( ls -ld "$app_path" ) + link=${ls#*' -> '} + case $link in #( + /*) app_path=$link ;; #( + *) app_path=$APP_HOME$link ;; + esac +done + +APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit + +APP_NAME="Gradle" +APP_BASE_NAME=${0##*/} + +# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"' + +# Use the maximum available, or set MAX_FD != -1 to use that value. +MAX_FD=maximum + +warn () { + echo "$*" +} >&2 + +die () { + echo + echo "$*" + echo + exit 1 +} >&2 + +# OS specific support (must be 'true' or 'false'). +cygwin=false +msys=false +darwin=false +nonstop=false +case "$( uname )" in #( + CYGWIN* ) cygwin=true ;; #( + Darwin* ) darwin=true ;; #( + MSYS* | MINGW* ) msys=true ;; #( + NONSTOP* ) nonstop=true ;; +esac + +CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar + + +# Determine the Java command to use to start the JVM. +if [ -n "$JAVA_HOME" ] ; then + if [ -x "$JAVA_HOME/jre/sh/java" ] ; then + # IBM's JDK on AIX uses strange locations for the executables + JAVACMD=$JAVA_HOME/jre/sh/java + else + JAVACMD=$JAVA_HOME/bin/java + fi + if [ ! -x "$JAVACMD" ] ; then + die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." + fi +else + JAVACMD=java + which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." +fi + +# Increase the maximum file descriptors if we can. +if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then + case $MAX_FD in #( + max*) + MAX_FD=$( ulimit -H -n ) || + warn "Could not query maximum file descriptor limit" + esac + case $MAX_FD in #( + '' | soft) :;; #( + *) + ulimit -n "$MAX_FD" || + warn "Could not set maximum file descriptor limit to $MAX_FD" + esac +fi + +# Collect all arguments for the java command, stacking in reverse order: +# * args from the command line +# * the main class name +# * -classpath +# * -D...appname settings +# * --module-path (only if needed) +# * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables. + +# For Cygwin or MSYS, switch paths to Windows format before running java +if "$cygwin" || "$msys" ; then + APP_HOME=$( cygpath --path --mixed "$APP_HOME" ) + CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" ) + + JAVACMD=$( cygpath --unix "$JAVACMD" ) + + # Now convert the arguments - kludge to limit ourselves to /bin/sh + for arg do + if + case $arg in #( + -*) false ;; # don't mess with options #( + /?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath + [ -e "$t" ] ;; #( + *) false ;; + esac + then + arg=$( cygpath --path --ignore --mixed "$arg" ) + fi + # Roll the args list around exactly as many times as the number of + # args, so each arg winds up back in the position where it started, but + # possibly modified. + # + # NB: a `for` loop captures its iteration list before it begins, so + # changing the positional parameters here affects neither the number of + # iterations, nor the values presented in `arg`. + shift # remove old arg + set -- "$@" "$arg" # push replacement arg + done +fi + +# Collect all arguments for the java command; +# * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of +# shell script including quotes and variable substitutions, so put them in +# double quotes to make sure that they get re-expanded; and +# * put everything else in single quotes, so that it's not re-expanded. + +set -- \ + "-Dorg.gradle.appname=$APP_BASE_NAME" \ + -classpath "$CLASSPATH" \ + org.gradle.wrapper.GradleWrapperMain \ + "$@" + +# Use "xargs" to parse quoted args. +# +# With -n1 it outputs one arg per line, with the quotes and backslashes removed. +# +# In Bash we could simply go: +# +# readarray ARGS < <( xargs -n1 <<<"$var" ) && +# set -- "${ARGS[@]}" "$@" +# +# but POSIX shell has neither arrays nor command substitution, so instead we +# post-process each arg (as a line of input to sed) to backslash-escape any +# character that might be a shell metacharacter, then use eval to reverse +# that process (while maintaining the separation between arguments), and wrap +# the whole thing up as a single "set" statement. +# +# This will of course break if any of these variables contains a newline or +# an unmatched quote. +# + +eval "set -- $( + printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" | + xargs -n1 | + sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' | + tr '\n' ' ' + )" '"$@"' + +exec "$JAVACMD" "$@" diff --git a/gradlew.bat b/gradlew.bat new file mode 100644 index 0000000..107acd3 --- /dev/null +++ b/gradlew.bat @@ -0,0 +1,89 @@ +@rem +@rem Copyright 2015 the original author or authors. +@rem +@rem Licensed under the Apache License, Version 2.0 (the "License"); +@rem you may not use this file except in compliance with the License. +@rem You may obtain a copy of the License at +@rem +@rem https://www.apache.org/licenses/LICENSE-2.0 +@rem +@rem Unless required by applicable law or agreed to in writing, software +@rem distributed under the License is distributed on an "AS IS" BASIS, +@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +@rem See the License for the specific language governing permissions and +@rem limitations under the License. +@rem + +@if "%DEBUG%" == "" @echo off +@rem ########################################################################## +@rem +@rem Gradle startup script for Windows +@rem +@rem ########################################################################## + +@rem Set local scope for the variables with windows NT shell +if "%OS%"=="Windows_NT" setlocal + +set DIRNAME=%~dp0 +if "%DIRNAME%" == "" set DIRNAME=. +set APP_BASE_NAME=%~n0 +set APP_HOME=%DIRNAME% + +@rem Resolve any "." and ".." in APP_HOME to make it shorter. +for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi + +@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m" + +@rem Find java.exe +if defined JAVA_HOME goto findJavaFromJavaHome + +set JAVA_EXE=java.exe +%JAVA_EXE% -version >NUL 2>&1 +if "%ERRORLEVEL%" == "0" goto execute + +echo. +echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. +echo. +echo Please set the JAVA_HOME variable in your environment to match the +echo location of your Java installation. + +goto fail + +:findJavaFromJavaHome +set JAVA_HOME=%JAVA_HOME:"=% +set JAVA_EXE=%JAVA_HOME%/bin/java.exe + +if exist "%JAVA_EXE%" goto execute + +echo. +echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% +echo. +echo Please set the JAVA_HOME variable in your environment to match the +echo location of your Java installation. + +goto fail + +:execute +@rem Setup the command line + +set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar + + +@rem Execute Gradle +"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %* + +:end +@rem End local scope for the variables with windows NT shell +if "%ERRORLEVEL%"=="0" goto mainEnd + +:fail +rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of +rem the _cmd.exe /c_ return code! +if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 +exit /b 1 + +:mainEnd +if "%OS%"=="Windows_NT" endlocal + +:omega diff --git a/settings.gradle.kts b/settings.gradle.kts new file mode 100644 index 0000000..a21d8df --- /dev/null +++ b/settings.gradle.kts @@ -0,0 +1,3 @@ + +rootProject.name = "SharedMutableState" + diff --git a/src/main/kotlin/ConsumerProducer.kt b/src/main/kotlin/ConsumerProducer.kt new file mode 100644 index 0000000..84c1c76 --- /dev/null +++ b/src/main/kotlin/ConsumerProducer.kt @@ -0,0 +1,67 @@ +import kotlinx.coroutines.delay +import kotlinx.coroutines.launch +import kotlinx.coroutines.runBlocking + +fun main(args: Array) = runBlocking { + val kitchen = Kitchen((2..8).random()) + repeat((10..20).random()) { + launch { + Consumer( + hunger = (2..8).random(), + kitchen = kitchen, + whenConsuming = { it?.let { println("Yummy $it") } ?: run { println("I'm still hungry :(") } } + ).start() + } + } + repeat((50..70).random()) { + launch { + Producer(kitchen).start() + } + } +} + +class Consumer( + private val hunger: Int, + private val kitchen: Kitchen, + private val whenConsuming: (String?) -> Unit +) { + + suspend fun start() { + TODO("Not yet implemented") + } + + private suspend fun consume(product: String?) { + delay((1L..30L).random()) + whenConsuming(product) + } + + private suspend fun collect(): String? { + delay((5L..10L).random()) + TODO("Not yet implemented") + } +} + +class Producer( + private val kitchen: Kitchen, + private val whenProducing: (String?) -> Unit = {} +) { + suspend fun start() { + while (true) { + TODO("Not yet implemented") + } + } + + private suspend fun produce(): String { + delay((30L..60L).random()) + whenProducing("Weißwurst") + return "Weißwurst" + } + + private suspend fun deliver(product: String) { + delay((5L..10L).random()) + } +} + +class Kitchen(capacity: Int) { + //TODO +} diff --git a/src/main/kotlin/DiningPhilosophers.kt b/src/main/kotlin/DiningPhilosophers.kt new file mode 100644 index 0000000..24a579f --- /dev/null +++ b/src/main/kotlin/DiningPhilosophers.kt @@ -0,0 +1,104 @@ +import kotlinx.coroutines.delay +import kotlinx.coroutines.launch +import kotlinx.coroutines.runBlocking + +class Fork(id: String) : Observable(id) { + + //TODO + // --------------- EDIT CODE BELOW --------------- + + suspend fun take(philosopher: String) { + setOccupiedBy(philosopher) + } + + suspend fun release() { + setOccupiedBy(null) + } + + // --------------- EDIT CODE ABOVE --------------- + + private suspend fun setOccupiedBy(philosopher: String?) { + delay(5L) + onChange(philosopher) + occupiedBy = philosopher + } + + private var occupiedBy: String? = null + + fun available() = occupiedBy == null +} + +class Philosopher( + id: String, + private val leftFork: Fork, + private val rightFork: Fork, +) : Observable(id) { + + //TODO + // --------------- EDIT CODE BELOW --------------- + + suspend fun start() = repeat(10) { + + }.also { changeState("FINISHED") } + + private suspend fun takeForks() { + leftFork.take(id) + rightFork.take(id) + } + + // --------------- EDIT CODE ABOVE --------------- + + private suspend fun wait() { + delay(1) + } + + private suspend fun eat() { + changeState("EATING") + delay((0L..10L).random()) + } + + private suspend fun think() { + changeState("THINKING") + delay((0L..10L).random()) + changeState("HUNGRY") + } + + private suspend fun changeState(state: String) { + onChange(state) + this.state = state + } + + private var state = "THINKING" +} + +open class Observable(val id: String) { + var onChange: suspend (String, T) -> Unit = { _, _ -> } + protected suspend fun onChange(state: T) = onChange(id, state) +} + +suspend fun main(args: Array) = runBlocking { + val number = 5 + val forks = Array(number) { Fork("Fork$it") } + val philosophers = Array(number) { index -> + Philosopher( + id = "Philosopher$index", + leftFork = forks[index], + rightFork = forks[(index + 1) % number] + ) + } + + philosophers.forEach { + it.onChange = { philosopher, state -> + println("$philosopher is now $state") + } + } + forks.forEach { + it.onChange = { fork, philosopher -> + println(philosopher?.let { "$fork acquired by $it" } ?: "$fork released") + } + } + + philosophers.forEach { + launch { it.start() } + } +} diff --git a/src/test/kotlin/ConsumerProducerTest.kt b/src/test/kotlin/ConsumerProducerTest.kt new file mode 100644 index 0000000..8407b19 --- /dev/null +++ b/src/test/kotlin/ConsumerProducerTest.kt @@ -0,0 +1,58 @@ +import io.kotest.core.spec.style.StringSpec +import io.kotest.matchers.shouldBe +import io.kotest.property.Arb +import io.kotest.property.Exhaustive +import io.kotest.property.arbitrary.next +import io.kotest.property.arbitrary.positiveInt +import io.kotest.property.exhaustive.cartesian +import io.kotest.property.exhaustive.exhaustive +import kotlinx.coroutines.async +import kotlinx.coroutines.awaitAll +import java.util.concurrent.atomic.AtomicInteger + +class ConsumerProducerTest : StringSpec() { + + private val consumerNumber = listOf(2, 5, 18).exhaustive() + private val producerNumber = listOf(3, 26, 39).exhaustive() + private val capacity = listOf(1, 5, 12).exhaustive() + private val hunger = Arb.positiveInt(max = 50) + + init { + + Exhaustive.cartesian(consumerNumber, producerNumber, capacity) { c, p, n -> + "$c consumers, $p producers, capacity $n" { + val consumerCounters = Array(c) { AtomicInteger(0) } + val consumerHunger = Array(p) { hunger.next() } + val producerCounter = AtomicInteger(0) + val kitchen = Kitchen(n) + val consumers = (0..p).map { index -> + async { + Consumer( + hunger = consumerHunger[index], + kitchen = kitchen, + whenConsuming = { if (it == "Weißwurst") consumerCounters[index].getAndIncrement() } + ).start() + } + } + val producers = (0..p).map { + async { + Producer( + kitchen = kitchen, + whenProducing = { if (it == "Weißwurst") producerCounter.getAndIncrement() } + ).start() + } + } + consumers.awaitAll() + producers.awaitAll() + + consumerCounters.forEachIndexed { i, c -> + c shouldBe consumerHunger[i] + } + + consumerCounters.fold(0) { sum, counter -> + sum + counter.get() + } shouldBe producerCounter.get() + } + } + } +} diff --git a/src/test/kotlin/DiningPhilosophersTest.kt b/src/test/kotlin/DiningPhilosophersTest.kt new file mode 100644 index 0000000..f40ef58 --- /dev/null +++ b/src/test/kotlin/DiningPhilosophersTest.kt @@ -0,0 +1,200 @@ +import io.kotest.assertions.fail +import io.kotest.core.spec.style.StringSpec +import io.kotest.matchers.longs.shouldBeLessThan +import io.kotest.matchers.shouldBe +import io.kotest.property.checkAll +import io.kotest.property.exhaustive.exhaustive +import kotlinx.coroutines.CompletableDeferred +import kotlinx.coroutines.CoroutineScope +import kotlinx.coroutines.Dispatchers +import kotlinx.coroutines.ObsoleteCoroutinesApi +import kotlinx.coroutines.channels.SendChannel +import kotlinx.coroutines.channels.actor +import kotlinx.coroutines.launch +import kotlinx.coroutines.withContext +import kotlin.system.measureTimeMillis +import kotlin.time.Duration.Companion.milliseconds + +@OptIn(ObsoleteCoroutinesApi::class) +class DiningPhilosophersTest : StringSpec() { + + init { + coroutineDebugProbes = true + timeout = 2000 + val philosopherNumbers = listOf(2, 5, 12).exhaustive() + + + "No Deadlock" { + philosopherNumbers.checkAll { n -> + println("-----Seating $n philosophers-----") + val diningPhilosopherLogger = actor { + val forks = HashMap() + for (msg in channel) { + when { + msg.id.contains("Fork") -> { + forks[msg.id] = msg.state + if (forks.entries.filter { it.value != null }.groupBy { it.value }.size == n) { + fail( + "All forks are blocked by pair wise distinct philosophers. This usually results in a dead lock. " + + "Some solutions to deadlocks won't resolve this test. If the other tests run successfully ignore this." + ) + } + } + } + } + } + withContext(Dispatchers.Default) { + philosophyTime(n, diningPhilosopherLogger) + } + diningPhilosopherLogger.close() + } + } + + "All philosophers think 10 times" { + philosopherNumbers.checkAll { n -> + println("-----Seating $n philosophers-----") + val diningPhilosopherLogger = observingActor() + philosophyTime(n, diningPhilosopherLogger) + val response = CompletableDeferred>>() + diningPhilosopherLogger.send(ReadLogMessage(response)) + + response.await() + .filter { it.first.contains("Philosophers") } + .filter { it.second == "THINKING" } + .groupBy { it.first } + .apply { + size shouldBe n + forEach { + it.value.size shouldBe n + } + } + + diningPhilosopherLogger.close() + } + } + + "Philosopher eat after thinking" { + philosopherNumbers.checkAll { n -> + println("-----Seating $n philosophers-----") + val diningPhilosopherLogger = observingActor() + philosophyTime(n, diningPhilosopherLogger) + val response = CompletableDeferred>>() + diningPhilosopherLogger.send(ReadLogMessage(response)) + + response.await() + .filter { it.first.contains("Philosophers") } + .groupBy { it.first } + .map { it.value.map { it.second }.iterator() } + .forEach { + while (it.hasNext()) { + val x = it.next() + if (it.hasNext()) { + x shouldBe "THINKING" + } else { + x shouldBe "FINISHED" + break + } + it.next() shouldBe "HUNGRY" + it.next() shouldBe "EATING" + } + } + + diningPhilosopherLogger.close() + } + } + + "Forks are not obtained when still used" { + philosopherNumbers.checkAll { n -> + println("-----Seating $n philosophers-----") + val diningPhilosopherLogger = actor { + val forks = HashMap() + for (msg in channel) { + when { + msg.id.contains("Fork") -> { + if (msg.state != null && forks[msg.id] != null) { + fail("${msg.state} tried to acquire ${msg.id} which is currently acquired by ${forks[msg.id]}") + } + forks[msg.id] = msg.state + } + } + } + } + philosophyTime(n, diningPhilosopherLogger) + diningPhilosopherLogger.close() + } + } + + "Philosophers obtain 2 forks before eating" { + philosopherNumbers.checkAll { n -> + println("-----Seating $n philosophers-----") + val diningPhilosopherLogger = actor { + val forks = HashMap() + for (msg in channel) { + when { + msg.id.contains("Fork") -> forks[msg.id] = msg.state + msg.state == "EATING" -> { + if (forks.filterValues { it == msg.id }.size != 2) { + fail("${msg.id} tried eating without acquiring 2 forks first. Acquired forks: ${forks.filterValues { it == msg.id }}") + } + } + } + } + } + philosophyTime(n, diningPhilosopherLogger) + diningPhilosopherLogger.close() + } + } + + "Use some parallelization".config(timeout = 40000.milliseconds) { + val measureTimeMillis = measureTimeMillis { + repeat(10) { + philosophyTime(10) + } + } + println("Finished in $measureTimeMillis") + measureTimeMillis shouldBeLessThan 35000 + } + } + + private fun CoroutineScope.observingActor() = + actor { + val log = ArrayList>() + for (msg in channel) { + when (msg) { + is LogMessage -> log.add(Pair(msg.id, msg.state)) + is ReadLogMessage -> msg.response.complete(log) + } + } + } + + private suspend fun philosophyTime(number: Int, channel: SendChannel? = null) = withContext(Dispatchers.Default) { + val forks = Array(number) { Fork("Fork$it") } + val philosophers = Array(number) { index -> + Philosopher( + id = "Philosopher$index", + leftFork = forks[index], + rightFork = forks[(index + 1) % number] + ) + } + philosophers.forEach { + it.onChange = { philosopher, state -> + channel?.send(LogMessage(philosopher, state)) + println("$philosopher is now $state") + } + } + forks.forEach { + it.onChange = { fork, philosopher -> + println(philosopher?.let { "$fork acquired by $it" } ?: "$fork released") + channel?.send(LogMessage(fork, philosopher)) + } + } + philosophers.forEach { + launch { it.start() } + } + } + + sealed class ObserverMessage + class ReadLogMessage(val response: CompletableDeferred>>) : ObserverMessage() + class LogMessage(val id: String, val state: String?) : ObserverMessage() +} +