Share logging file with Dart plugin

src/io/flutter/FlutterInitializer.java

@@ -83,6 +83,8 @@ public class FlutterInitializer extends FlutterProjectActivity {
 
   @Override
   public void executeProjectStartup(@NotNull Project project) {
+    PluginLogger.initLogger();
+
     // This sets the correct log level and listens for future changes.
     PluginLogger.updateLogLevel();
     FlutterSettings.getInstance().addListener(PluginLogger::updateLogLevel);

src/io/flutter/logging/PluginLogger.java

@@ -10,41 +10,109 @@
 import com.intellij.openapi.diagnostic.Logger;
 import io.flutter.settings.FlutterSettings;
 import org.jetbrains.annotations.NotNull;
+import org.jspecify.annotations.Nullable;
 
 import java.io.File;
 import java.io.IOException;
 import java.util.logging.FileHandler;
+import java.util.logging.Handler;
+import java.util.logging.Level;
+import java.util.logging.LogManager;
 import java.util.logging.SimpleFormatter;
 
 public class PluginLogger {
   public static final String LOG_FILE_NAME = "dash.log";
 
-  // This handler specifies the logging format and location.
-  private static final FileHandler fileHandler;
+  private static final String FLUTTER_ROOT_LOGGER_NAME = "io.flutter";
+  private static final int MAX_LOG_SIZE = 10 * 1024 * 1024;
+  private static final int MAX_LOG_FILES = 5;
+  private static final String LOG_FORMAT_STRING = "%1$tF %1$tT %3$s [%4$-7s] %5$s %6$s %n";
+
+  // Add the handler to the root logger so that all classes within `io.flutter`
+  // log to the file correctly. We can also update the log level
+  // of all classes at once by changing the root logger level.
+  private static final java.util.logging.Logger rootLogger = java.util.logging.Logger.getLogger(FLUTTER_ROOT_LOGGER_NAME);
+  private static final java.util.logging.Logger dartLogger = java.util.logging.Logger
+    .getLogger("com.jetbrains.lang.dart");
+
+  private static boolean isInitialized = false;
+
+  public static void initLogger() {
+    if (isInitialized) return;
 
-  static {
     final String logPath = PathManager.getLogPath();
-    try {
-      fileHandler = new FileHandler(logPath + File.separatorChar + LOG_FILE_NAME, 1024 * 1024, 1);
+    String fullPath = logPath + File.separatorChar + LOG_FILE_NAME;
+
+    synchronized (LogManager.getLogManager()) {
+      isInitialized = true;
+      // Try to find an existing FileHandler on either logger
+      FileHandler existingHandler = getExistingFileHandler(rootLogger);
+      if (existingHandler == null) {
+        existingHandler = getExistingFileHandler(dartLogger);
+      }
+
+      if (existingHandler != null) {
+        // Another plugin initialized first; reuse its handler
+        ensureHandlerSet(rootLogger, existingHandler);
+      }
+      else {
+        // We are the first plugin to initialize; create the handler
+        try {
+          FileHandler newHandler = new FileHandler(fullPath, MAX_LOG_SIZE, MAX_LOG_FILES, true);
+          newHandler.setFormatter(createLogFormatter());
+
+          // Attach to logger so the next plugin finds it
+          ensureHandlerSet(rootLogger, newHandler);
+        }
+        catch (IOException | SecurityException e) {
+          java.util.logging.Logger.getLogger(PluginLogger.class.getName())
+            .log(Level.WARNING, "Failed to initialize plugin log file handler", e);
+        }
+      }
     }
-    catch (IOException e) {
-      throw new RuntimeException(e);
+  }
+
+  private static void ensureHandlerSet(java.util.logging.Logger logger, FileHandler handler) {
+    if (logger != null) {
+      Handler[] handlers = logger.getHandlers();
+      boolean hasHandler = handlers != null && java.util.Arrays.stream(handlers).anyMatch(h -> h == handler);
+      if (!hasHandler) {
+        logger.addHandler(handler);
+      }
     }
-    System.setProperty("java.util.logging.SimpleFormatter.format",
-                       "%1$tF %1$tT %3$s [%4$-7s] %5$s %6$s %n");
-    fileHandler.setFormatter(new SimpleFormatter());
   }
 
-  // Add the handler to the root logger so that all classes within `io.flutter` log to the file correctly. We can also update the log level
-  // of all classes at once by changing the root logger level.
-  private static final java.util.logging.Logger rootLogger = java.util.logging.Logger.getLogger("io.flutter");
+  private static @Nullable FileHandler getExistingFileHandler(java.util.logging.Logger logger) {
+    if (logger == null) return null;
+    Handler[] handlers = logger.getHandlers();
+    if (handlers != null) {
+      for (Handler handler : handlers) {
+        if (handler instanceof FileHandler) {
+          return (FileHandler)handler;
+        }
+      }
+    }
+    return null;
+  }
 
-  static {
-    rootLogger.addHandler(fileHandler);
+  private static @NotNull java.util.logging.Formatter createLogFormatter() {
+    return new java.util.logging.Formatter() {
+      @Override
+      public String format(java.util.logging.LogRecord record) {
+        return String.format(LOG_FORMAT_STRING,
+          new java.util.Date(record.getMillis()),
+          null, // Not using source name in the format string
+          record.getLoggerName(),
+          record.getLevel().getLocalizedName(),
+          super.formatMessage(record),
+          (record.getThrown() != null ? "\n" + com.intellij.openapi.util.text.StringUtil.getThrowableText(record.getThrown()) : "")
+        );
+      }
+    };
   }
 
   public static void updateLogLevel() {
-    final Logger rootLoggerInstance = Logger.getInstance("io.flutter");
+    final Logger rootLoggerInstance = Logger.getInstance(FLUTTER_ROOT_LOGGER_NAME);
     // Workaround for https://github.com/flutter/flutter-intellij/issues/8631
     if (rootLoggerInstance.getClass().getName().equals("com.haulmont.jmixstudio.logger.JmixLoggerWrapper")) {
       return;