Adds initial version for the reference implementation

.github/workflows/cc.yaml

@@ -0,0 +1,17 @@
+name: Continuous Check
+
+on: [push]
+
+jobs:
+  build:
+    name: Continuous Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Java 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: 21
+          distribution: temurin
+      - name: Build with Gradle
+        run: ./gradlew check --info

.gitignore

@@ -1,24 +1,5 @@
-# Compiled class file
-*.class
-
-# Log file
-*.log
-
-# BlueJ files
-*.ctxt
-
-# Mobile Tools for Java (J2ME)
-.mtj.tmp/
-
-# Package Files #
-*.jar
-*.war
-*.nar
-*.ear
-*.zip
-*.tar.gz
-*.rar
-
-# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
-hs_err_pid*
-replay_pid*
+build/**
+out/**
+bin/**
+.idea
+.gradle

README.md

@@ -1 +1,39 @@
-# s2324v-se3
+# s2324v-se3
+
+Reference implementation for the Concurrent Programming final project, Spring 2024.
+
+## Design notes
+
+The code in this repository implements a single-node _publish-subscriber_ system (pub-sub), with a TCP/IP interface.
+
+Client systems interact with the pub-sub system via the establishment of TCP/IP connections and the sending of 
+_requests_ through these connections.
+The available _request_ types are defined in [ClientRequest](src/main/kotlin/pt/isel/pc/protocol/ClientRequest.kt).
+For each _request_, the server must reply with a _response_ - 
+[ClientResponse](src/main/kotlin/pt/isel/pc/protocol/ClientResponse.kt).
+
+The server can also take the initiative to send messages to clients, without them being responses to requests.
+These messages are called _server pushes_ and are defined in [ServerPush](src/main/kotlin/pt/isel/pc/protocol/ServerPush.kt).
+
+The way strings are transformed into _requests_ (i.e. parsing) 
+and how _responses_ and _server pushes_ are transformed into strings (i.e. serialization) is defined in 
+[ParseAndSerialize](src/main/kotlin/pt/isel/pc/protocol/ParseAndSerialize.kt).
+
+The design for some components of this system is inspired in the [actor model](https://en.wikipedia.org/wiki/Actor_model).
+
+The [Server](src/main/kotlin/pt/isel/pc/Server.kt) is responsible for:
+- Creating a server socket and binding it to an IP address and a port.
+- Manage the association between topics and subscribers.
+- Accept connections from remote clients and create the data structures and threads required to deal with those clients.
+- The server is composed by two threads:
+  - a _main_ thread, implementing the main server domain logic and state, namely the list of remote clients and topics.
+  - a _accept_ thread, responsible for accepting new connections.
+- The _main_ thread runs a loop that
+  - retrieves _control messages_ from a _control queue_.
+  - changes internal state based on those control messages.
+  - produces side effects based on those control message.
+- With few exceptions (e.g. the server socket), all server state is exclusively managed by the _main_ thread.
+- All interaction with the server is done by sending control messages to the server's _control queue_.
+- 
+The [RemoteClient] [RemoteClient](src/main/kotlin/pt/isel/pc/RemoteClient.kt) is responsible to interact with a 
+specific connected client, and follows a similar design.

build.gradle.kts

@@ -0,0 +1,61 @@
+
+
+plugins {
+    kotlin("jvm") version "1.9.21"
+}
+
+group = "pt.isel"
+version = "1.0-SNAPSHOT"
+
+repositories {
+    mavenCentral()
+}
+
+val ktlint: Configuration by configurations.creating
+
+dependencies {
+    implementation("org.slf4j:slf4j-api:1.7.36")
+    implementation("org.slf4j:slf4j-simple:2.0.0-alpha7")
+
+    testImplementation("org.jetbrains.kotlin:kotlin-test")
+    ktlint("com.pinterest:ktlint:0.48.2") {
+        attributes {
+            attribute(Bundling.BUNDLING_ATTRIBUTE, objects.named(Bundling.EXTERNAL))
+        }
+    }
+}
+
+tasks.test {
+    useJUnitPlatform()
+    // To access the *non-public* Continuation API
+    // ONLY for learning purposes
+    jvmArgs(listOf(
+        "--add-exports", "java.base/jdk.internal.vm=ALL-UNNAMED"
+    ))
+}
+kotlin {
+    jvmToolchain(21)
+}
+
+val outputDir = "${layout.buildDirectory}/reports/ktlint/"
+val inputFiles = project.fileTree(mapOf("dir" to "src", "include" to "**/*.kt"))
+val ktlintCheck by tasks.creating(JavaExec::class) {
+    inputs.files(inputFiles)
+    outputs.dir(outputDir)
+
+    description = "Check Kotlin code style."
+    classpath = ktlint
+    mainClass.set("com.pinterest.ktlint.Main")
+    args = listOf("src/**/*.kt")
+}
+
+tasks.named("check") {
+    dependsOn("ktlintCheck")
+}
+
+// Use the following to run:
+// java -cp "build/libs/*:build/classes/kotlin/main" <package>.<class-name>Kt
+tasks.register<Copy>("packLibs") {
+    from(configurations.runtimeClasspath)
+    into("build/libs")
+}

gradle.properties

@@ -0,0 +1 @@
+kotlin.code.style=official

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Mon Feb 19 19:18:35 WET 2024
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.5-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

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 "$JAVACMD" "$@"