[HDFS-13428] RBF: Remove LinkedList From StateStoreFileImpl.java

• Type: Sub-task
• Status: Resolved
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 3.0.1
• Fix Version/s: 2.10.0, 3.2.0, 3.1.1, 2.9.2, 3.0.3
• Component/s: federation
• Hadoop Flags: Reviewed
• Flags: Patch
• Assignee: David Mollitor
• Reporter: David Mollitor
• Created: 11/Apr/18 12:49
• Updated: 09/May/18 05:12
• Resolved: 11/Apr/18 17:44

Description

Replace LinkedList with ArrayList implementation in the StateStoreFileImpl class.  This is especially advantageous because we can pre-allocate the internal array before a copy occurs.  ArrayList is faster for iterations and requires less memory than LinkedList.

  protected List<String> getChildren(String path) {
    List<String> ret = new LinkedList<>();
    File dir = new File(path);
    File[] files = dir.listFiles();
    if (files != null) {
      for (File file : files) {
        String filename = file.getName();
        ret.add(filename);
      }
    }
    return ret;
  }