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Add Dining Philosopher and Consumer Producer base code structure

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This commit is contained in:
jwaibel
2022-09-23 05:06:34 +02:00
commit 83e6b4d4c6
12 changed files with 792 additions and 0 deletions
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.gitignore vendored Normal file
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/build

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build.gradle.kts Normal file
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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<KotlinCompile> {
kotlinOptions.jvmTarget = "1.8"
}

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gradle.properties Normal file
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kotlin.code.style=official

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gradle/wrapper/gradle-wrapper.jar vendored Normal file
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gradle/wrapper/gradle-wrapper.properties vendored Normal file
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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

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#!/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 "$JAVACMD" "$@"

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@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

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rootProject.name = "SharedMutableState"

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src/main/kotlin/ConsumerProducer.kt Normal file
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import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
fun main(args: Array<String>) = 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
}

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src/main/kotlin/DiningPhilosophers.kt Normal file
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import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
class Fork(id: String) : Observable<String?>(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<String>(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<T>(val id: String) {
var onChange: suspend (String, T) -> Unit = { _, _ -> }
protected suspend fun onChange(state: T) = onChange(id, state)
}
suspend fun main(args: Array<String>) = 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() }
}
}

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src/test/kotlin/ConsumerProducerTest.kt Normal file
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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()
}
}
}
}

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src/test/kotlin/DiningPhilosophersTest.kt Normal file
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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<LogMessage> {
val forks = HashMap<String, String?>()
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<List<Pair<String, String?>>>()
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<List<Pair<String, String?>>>()
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 $n philosophers-----")
val diningPhilosopherLogger = actor<LogMessage> {
val forks = HashMap<String, String?>()
for (msg in channel) {
when {
msg.id.contains("Fork") -> {
if (msg.state != null && forks[msg.id] != null) {
fail("${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 $n philosophers-----")
val diningPhilosopherLogger = actor<LogMessage> {
val forks = HashMap<String, String?>()
for (msg in channel) {
when {
msg.id.contains("Fork") -> forks[msg.id] = msg.state
msg.state == "EATING" -> {
if (forks.filterValues { it == msg.id }.size != 2) {
fail("${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 $measureTimeMillis")
measureTimeMillis shouldBeLessThan 35000
}
}
private fun CoroutineScope.observingActor() =
actor<ObserverMessage> {
val log = ArrayList<Pair<String, String?>>()
for (msg in channel) {
when (msg) {
is LogMessage -> log.add(Pair(msg.id, msg.state))
is ReadLogMessage -> msg.response.complete(log)
}
}
}
private suspend fun philosophyTime(number: Int, channel: SendChannel<LogMessage>? = null) = withContext(Dispatchers.Default) {
val forks = Array(number) { Fork("Fork$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<List<Pair<String, String?>>>) : ObserverMessage()
class LogMessage(val id: String, val state: String?) : ObserverMessage()
}