Fix tracer logging when instrumenting Gradle Daemon

dd-java-agent/agent-logging/src/main/java/datadog/trace/logging/ddlogger/DDLoggerFactory.java

@@ -75,4 +75,9 @@ private LoggerHelperFactory getHelperFactory() {
     }
     return factory;
   }
+
+  @Override
+  public void reinitialize() {
+    helperFactory = null;
+  }
 }

dd-java-agent/instrumentation/gradle/src/main/groovy/datadog/trace/instrumentation/gradle/GradleDaemonLoggingInstrumentation.java

@@ -0,0 +1,47 @@
+package datadog.trace.instrumentation.gradle;
+
+import static datadog.trace.agent.tooling.bytebuddy.matcher.NameMatchers.named;
+
+import com.google.auto.service.AutoService;
+import datadog.trace.agent.tooling.Instrumenter;
+import datadog.trace.logging.GlobalLogLevelSwitcher;
+import net.bytebuddy.asm.Advice;
+
+@AutoService(Instrumenter.class)
+public class GradleDaemonLoggingInstrumentation extends Instrumenter.CiVisibility
+    implements Instrumenter.ForSingleType {
+
+  public GradleDaemonLoggingInstrumentation() {
+    super("gradle", "gradle-daemon-logging");
+  }
+
+  @Override
+  public String instrumentedType() {
+    return "org.gradle.launcher.daemon.bootstrap.DaemonMain";
+  }
+
+  @Override
+  public void adviceTransformations(AdviceTransformation transformation) {
+    transformation.applyAdvice(
+        named("initialiseLogging"),
+        GradleDaemonLoggingInstrumentation.class.getName() + "$ReinitialiseLogging");
+  }
+
+  /**
+   * Gradle Daemon closes original {@link System.out} and {@link System.err} streams (see {@link
+   * org.gradle.launcher.daemon.bootstrap.DaemonMain#daemonStarted}), and replaces them with Gradle
+   * Daemon log streams (see {@link
+   * org.gradle.launcher.daemon.bootstrap.DaemonMain#initialiseLogging}).
+   *
+   * <p>{@link datadog.trace.logging.simplelogger.SLCompatFactory} that contains logging settings
+   * gets initialized before Gradle Daemon, so DD logging settings refer to the original streams
+   * that the daemon closes. They need to refer to the new streams created by the daemon, so here we
+   * reset the settings letting them re-initialize to capture the new streams.
+   */
+  public static class ReinitialiseLogging {
+    @Advice.OnMethodExit(suppress = Throwable.class)
+    public static void reinitialiseTracerLogging() {
+      GlobalLogLevelSwitcher.get().reinitialize();
+    }
+  }
+}

internal-api/src/main/java/datadog/trace/logging/GlobalLogLevelSwitcher.java

@@ -43,4 +43,11 @@ public void restore() {
       delegate.restore();
     }
   }
+
+  @Override
+  public void reinitialize() {
+    if (delegate != null) {
+      delegate.reinitialize();
+    }
+  }
 }

internal-api/src/main/java/datadog/trace/logging/LogLevelSwitcher.java

@@ -12,4 +12,7 @@ public interface LogLevelSwitcher {
 
   /** Restore the LogLevel to the original setting. */
   void restore();
+
+  /** Re-execute logging settings initialization */
+  void reinitialize();
 }