refactor: logging in separate module

orchestrator/src/main/kotlin/Main.kt

@@ -3,10 +3,10 @@ package technology.idlab
 import java.io.File
 import kotlin.system.exitProcess
 import kotlinx.coroutines.runBlocking
+import technology.idlab.log.Log
 import technology.idlab.orchestrator.impl.SimpleOrchestrator
 import technology.idlab.parser.impl.JenaParser
 import technology.idlab.resolver.impl.GenericResolver
-import technology.idlab.util.Log
 import technology.idlab.util.ManagedProcess
 
 /**

orchestrator/src/main/kotlin/broker/impl/SimpleBroker.kt

@@ -3,7 +3,7 @@ package technology.idlab.broker.impl
 import technology.idlab.broker.Broker
 import technology.idlab.broker.BrokerClient
 import technology.idlab.broker.BrokerException
-import technology.idlab.util.Log
+import technology.idlab.log.Log
 
 typealias Clients<T> = Pair<Int, MutableSet<BrokerClient<T>>>
 

orchestrator/src/main/kotlin/log/Log.kt

@@ -0,0 +1,75 @@
+package technology.idlab.log
+
+import technology.idlab.log.pretty.PrettyLog
+
+abstract class Log(
+    // The current log level. Messages with a level lower than this will not be printed.
+    private val level: LogLevel
+) {
+  /**
+   * Print a message to the output using a given level.
+   *
+   * @param message The message to print.
+   * @param level The level of the message.
+   */
+  abstract fun log(message: String, level: LogLevel)
+
+  /**
+   * Print a message if and only if the debug flag is set. Note that the message will not be
+   * evaluated lazily.
+   *
+   * @param message The message to print.
+   */
+  fun debug(message: String) {
+    log(message, LogLevel.DEBUG)
+  }
+
+  /**
+   * Print a message if and only if the debug flag is set. Note that the message will be evaluated
+   * lazily only if the debug flag is set.
+   *
+   * @param message A function determining the message to print.
+   */
+  fun debug(message: () -> String) {
+    if (level == LogLevel.DEBUG) {
+      val computedMessage = message()
+      log(computedMessage, LogLevel.DEBUG)
+    }
+  }
+
+  /**
+   * Print a general info message. Will get outputted in all modes.
+   *
+   * @param message The message to print.
+   */
+  fun info(message: String) {
+    log(message, LogLevel.INFO)
+  }
+
+  /**
+   * Print a command message, which will be colored yellow in the console. The location, i.e. the
+   * file and line number, will be determined by the caller.
+   *
+   * @param message The message to print.
+   */
+  fun command(message: String) {
+    log(message, LogLevel.CMD)
+  }
+
+  /**
+   * Print a severe message, which will be colored red in the console.
+   *
+   * @param message The message to print.
+   */
+  fun severe(message: String) {
+    log(message, LogLevel.SEVERE)
+  }
+
+  companion object {
+    /**
+     * A globally available instance of the logger. Note that at its creation, the logger will
+     * output the header to the console, which is why we only allow a single instance.
+     */
+    val shared = PrettyLog(LogLevel.INFO)
+  }
+}

orchestrator/src/main/kotlin/log/LogLevel.kt

@@ -0,0 +1,8 @@
+package technology.idlab.log
+
+enum class LogLevel {
+  CMD,
+  DEBUG,
+  INFO,
+  SEVERE,
+}

orchestrator/src/main/kotlin/log/pretty/PrettyLog.kt

@@ -0,0 +1,76 @@
+package technology.idlab.log.pretty
+
+import java.time.format.DateTimeFormatter
+import java.util.*
+import technology.idlab.log.Log
+import technology.idlab.log.LogLevel
+
+private const val TIME_PADDING = 15
+private const val LEVEL_PADDING = 10
+private const val FILE_PADDING = 39
+private const val MESSAGE_PADDING = 87
+
+/**
+ * A simple logging class that prints messages to the console. The class is a singleton, and all
+ * messages are outputted to the console. The class has three levels of logging: DEBUG, INFO, and
+ * FATAL. DEBUG is for debugging information, INFO is for general information, and FATAL is for
+ * errors that will cause the program to exit. At the moment of writing, all levels are outputted to
+ * the console regardless of the debug flag.
+ */
+class PrettyLog(level: LogLevel) : Log(level) {
+  init {
+    val builder = StringBuilder()
+    builder.append("\u001B[1m")
+    builder.append("TIME".padEnd(TIME_PADDING, ' '))
+    builder.append("LEVEL".padEnd(LEVEL_PADDING, ' '))
+    builder.append("FILE".padEnd(FILE_PADDING, ' '))
+    builder.append("MESSAGE".padEnd(MESSAGE_PADDING, ' '))
+    builder.append("\n")
+    builder.append("\u001B[0m")
+    builder.append("----".padEnd(TIME_PADDING, ' '))
+    builder.append("-----".padEnd(LEVEL_PADDING, ' '))
+    builder.append("----".padEnd(FILE_PADDING, ' '))
+    builder.append("-------\n")
+
+    synchronized(System.out) { print(builder) }
+  }
+
+  override fun log(message: String, level: LogLevel) {
+    // Get the current time.
+    val instant = Date().toInstant()
+    val tz = instant.atZone(TimeZone.getDefault().toZoneId())
+    val iso = DateTimeFormatter.ISO_LOCAL_TIME
+
+    val time = tz.format(iso)
+    val levelCode = level.name
+
+    val stack = Throwable().stackTrace[4]
+    val file = "${stack.fileName ?: "Unknown"}:${stack.lineNumber}"
+
+    // Build the message.
+    val builder = StringBuilder()
+
+    // If the message is of level debug, set color to gray.
+    if (level == LogLevel.DEBUG) {
+      builder.append("\u001B[37m")
+    }
+
+    // If the message is of level command, set color to muted yellow.
+    if (level == LogLevel.CMD) {
+      builder.append("\u001B[38;5;180m")
+    }
+
+    // The actual message.
+    builder.append(time.padEnd(TIME_PADDING, ' '))
+    builder.append(levelCode.padEnd(LEVEL_PADDING, ' '))
+    builder.append(file.padEnd(FILE_PADDING, ' '))
+    builder.append(message)
+    builder.append("\n")
+
+    // Reset coloring.
+    builder.append("\u001B[0m")
+
+    // Print to the console, thread safe.
+    synchronized(System.out) { print(builder) }
+  }
+}

orchestrator/src/main/kotlin/parser/impl/JenaParser.kt

@@ -30,9 +30,9 @@ import technology.idlab.intermediate.parameter.LiteralParameter
 import technology.idlab.intermediate.parameter.NestedParameter
 import technology.idlab.intermediate.parameter.Parameter
 import technology.idlab.intermediate.runner.RunnerType
+import technology.idlab.log.Log
 import technology.idlab.parser.Parser
 import technology.idlab.parser.ParserException
-import technology.idlab.util.Log
 
 class JenaParser(
     /** A file pointer to the pipeline configuration entrypoint. */

orchestrator/src/main/kotlin/resolver/impl/GitResolver.kt

@@ -2,8 +2,8 @@ package technology.idlab.resolver.impl
 
 import java.io.File
 import technology.idlab.intermediate.IRDependency
+import technology.idlab.log.Log
 import technology.idlab.resolver.Resolver
-import technology.idlab.util.Log
 
 /** Resolve a Git repository by cloning it locally and reading its configuration file. */
 class GitResolver : Resolver {

orchestrator/src/main/kotlin/runner/impl/grpc/GRPCRunner.kt

@@ -18,8 +18,8 @@ import runner.impl.grpc.Config
 import technology.idlab.ConnectionException
 import technology.idlab.UnrecognizedRequestException
 import technology.idlab.intermediate.IRStage
+import technology.idlab.log.Log
 import technology.idlab.runner.Runner
-import technology.idlab.util.Log
 import technology.idlab.util.retries
 
 /**

orchestrator/src/main/kotlin/runner/impl/jvm/JVMRunner.kt

@@ -15,8 +15,8 @@ import technology.idlab.intermediate.IRStage
 import technology.idlab.intermediate.argument.LiteralArgument
 import technology.idlab.intermediate.argument.NestedArgument
 import technology.idlab.intermediate.parameter.LiteralParameterType
+import technology.idlab.log.Log
 import technology.idlab.runner.Runner
-import technology.idlab.util.Log
 
 private const val JVM_RUNNER_URI = "https://www.rdf-connect/#JVMRunner"
 

orchestrator/src/main/kotlin/runner/impl/jvm/Processor.kt

@@ -1,6 +1,6 @@
 package technology.idlab.runner.impl.jvm
 
-import technology.idlab.util.Log
+import technology.idlab.log.Log
 
 abstract class Processor(
     /**