Roll instrumentation log files.

pkg/analysis_server/lib/src/server/driver.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library driver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 365 matching lines @@
     } else {
       // No path to the SDK provided; use DirectoryBasedDartSdk.defaultSdk,
       // which will make a guess.
       defaultSdk = DirectoryBasedDartSdk.defaultSdk;
     }
     //
     // Initialize the instrumentation service.
     //
     String logFilePath = results[INSTRUMENTATION_LOG_FILE];
     if (logFilePath != null) {
+      _rollLogFiles(logFilePath, 5);
       FileInstrumentationServer fileBasedServer =
           new FileInstrumentationServer(logFilePath);
       instrumentationServer = instrumentationServer != null
           ? new MulticastInstrumentationServer(
               [instrumentationServer, fileBasedServer])
           : fileBasedServer;
     }
     InstrumentationService service =
         new InstrumentationService(instrumentationServer);
     service.logVersion(_readUuid(service), results[CLIENT_ID],
@@ skipping 174 matching lines @@
     try {
       uuidFile.parent.createSync(recursive: true);
       uuidFile.writeAsStringSync(uuid);
     } catch (exception, stackTrace) {
       service.logPriorityException(exception, stackTrace);
       // Slightly alter the uuid to indicate it was not persisted
       uuid = 'temp-$uuid';
     }
     return uuid;
   }
+
+  /**
+   * Perform log files rolling.
+   *
+   * Rename existing files with names `[path].(x)` to `[path].(x+1)`.
+   * Keep at most [numOld] files.
+   * Rename the file with the given [path] to `[path].1`.
+   */
+  static void _rollLogFiles(String path, int numOld) {
+    for (int i = numOld - 1; i >= 0; i--) {
+      try {
+        String oldPath = i == 0 ? path : '$path.$i';
+        new File(oldPath).renameSync('$path.${i+1}');

[Brian Wilkerson, 2015/11/04 23:00:29]

Does rename work if there's already a file with that name? If not, don't we need
to explicitly delete "$path.$numOld"?

[scheglov, 2015/11/05 16:40:27]

Yes, it does.

   /**
   * Synchronously renames this file. Returns a [File]
   * instance for the renamed file.
   *
   * If [newPath] identifies an existing file, that file is
   * replaced. If [newPath] identifies an existing directory the
   * operation fails and an exception is thrown.
   */
  File renameSync(String newPath);

+      } catch (e) {}
+    }
+  }
 }