Added logging capabilities using logback and secured default Standard…

… Output Stream to reserve it for LSP4j

.gitignore

@@ -1,2 +1,3 @@
 lsp
-target
+target
+logs

pom.xml

@@ -25,7 +25,9 @@
     <encoding>UTF-8</encoding>
     <scala.version>3.3.0</scala.version> <!-- Scala 2.12 not working because of copies of annotations issues -->
     <lsp4j.version>0.21.0</lsp4j.version>
-    <typesafe.version>1.4.2</typesafe.version>
+    <typesafe.config.version>1.4.2</typesafe.config.version>
+    <ujson.version>3.1.2</ujson.version>
+    <logback.version>1.4.11</logback.version>
   </properties>
 
 
@@ -47,13 +49,20 @@
     <dependency>
       <groupId>com.typesafe</groupId>
       <artifactId>config</artifactId>
-      <version>${typesafe.version}</version>
+      <version>${typesafe.config.version}</version>
     </dependency>
 
     <dependency>
       <groupId>com.lihaoyi</groupId>
       <artifactId>ujson_3</artifactId>
-      <version>3.1.2</version>
+      <version>${ujson.version}</version>
+    </dependency>
+
+    <!-- Logging -->
+    <dependency>
+      <groupId>ch.qos.logback</groupId>
+      <artifactId>logback-classic</artifactId>
+      <version>${logback.version}</version>
     </dependency>
 
 

src/main/resources/logback.xml

@@ -0,0 +1,24 @@
+<configuration>
+
+    <!-- Appender to write logs to a file -->
+    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
+        <file>logs/myapp.log</file> <!-- Change the file name as needed -->
+        <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
+            <fileNamePattern>logs/myapp.%i.log</fileNamePattern>
+            <minIndex>1</minIndex>
+            <maxIndex>10</maxIndex>
+        </rollingPolicy>
+        <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
+            <maxFileSize>10MB</maxFileSize>
+        </triggeringPolicy>
+        <encoder>
+            <pattern>%date{dd-MM-yyyy HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
+        </encoder>
+    </appender>
+
+    <!-- Root logger settings -->
+    <root level="info">
+        <appender-ref ref="FILE"/>
+    </root>
+
+</configuration>

src/main/scala/io/smartdatalake/Main.scala

@@ -1,26 +1,31 @@
 package io.smartdatalake
 
+import io.smartdatalake.logging.LoggingManager
 import io.smartdatalake.modules.AppModule
 import org.eclipse.lsp4j.jsonrpc.Launcher
 import org.eclipse.lsp4j.launch.LSPLauncher
 import org.eclipse.lsp4j.services.{LanguageClient, LanguageClientAware, LanguageServer}
 
-import java.io.{InputStream, PrintStream}
-import java.util.logging.{Level, LogManager, Logger}
+import java.io.{InputStream, OutputStream, PrintStream}
+import org.slf4j.LoggerFactory
 
 /**
  * @author scalathe
  */
+
 object Main extends AppModule {
 
   def main(args : Array[String]): Unit = {
 
-    // We're using Standard Input and Standard Output for communication.
-    LogManager.getLogManager.reset()
-    val globalLogger = Logger.getLogger(Logger.GLOBAL_LOGGER_NAME)
-    globalLogger.setLevel(Level.OFF)
+    // We're using Standard Input and Standard Output for communication, so we need to ensure Standard Output is only used by the LSP4j server.
+    // Keep a reference on the default standard output
+    val systemOut = System.out
+
+    // redirect default output to the same stream of the logback logger
+    LoggingManager.redirectStandardOutputToLoggerOutput()
 
-    startServer(System.in, System.out)
+    // give the Standard Output reference for the server.
+    startServer(System.in, systemOut)
   }
 
   private def startServer(in: InputStream, out: PrintStream) = {
@@ -29,7 +34,9 @@ object Main extends AppModule {
     val client: LanguageClient = launcher.getRemoteProxy
 
     helloLanguageServer.connect(client)
-
+    // Use the configured logger
+    val logger = LoggerFactory.getLogger(getClass)
+    logger.info("Server starts listening...")
     launcher.startListening().get()
   }
 

src/main/scala/io/smartdatalake/logging/LoggerOutputStream.scala

@@ -0,0 +1,18 @@
+package io.smartdatalake.logging
+
+import org.slf4j.Logger
+
+import java.io.OutputStream
+
+private[logging] class LoggerOutputStream(logger: Logger) extends OutputStream {
+  private val builder = new StringBuilder
+  override def write(b: Int): Unit = {
+    if (b == '\n') {
+      logger.info(builder.toString)
+      builder.clear()
+    } else {
+      builder.append(b.toChar)
+    }
+  }
+
+}

src/main/scala/io/smartdatalake/logging/LoggingManager.scala

@@ -0,0 +1,15 @@
+package io.smartdatalake.logging
+
+import org.slf4j.LoggerFactory
+
+import java.io.PrintStream
+
+object LoggingManager {
+
+  def redirectStandardOutputToLoggerOutput(): Unit =
+    val loggerRedirectedOutput = LoggerFactory.getLogger("redirectedOutput")
+    val redirectedPrintStream = new PrintStream(new LoggerOutputStream(loggerRedirectedOutput))
+    System.setOut(redirectedPrintStream)
+    println("Using new default output stream")
+
+}