Uploaded image for project: 'Lucene - Core'
  1. Lucene - Core
  2. LUCENE-2316

Define clear semantics for Directory.fileLength

    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 3.1, 4.0-ALPHA
    • Component/s: core/index
    • Labels:
      None
    • Lucene Fields:
      New, Patch Available

      Description

      On this thread: http://mail-archives.apache.org/mod_mbox/lucene-java-dev/201003.mbox/%3C126142c1003121525v24499625u1589bbef4c0792e7@mail.gmail.com%3E it was mentioned that Directory's fileLength behavior is not consistent between Directory implementations if the given file name does not exist. FSDirectory returns a 0 length while RAMDirectory throws FNFE.

      The problem is that the semantics of fileLength() are not defined. As proposed in the thread, we'll define the following semantics:

      • Returns the length of the file denoted by <code>name</code> if the file exists. The return value may be anything between 0 and Long.MAX_VALUE.
      • Throws FileNotFoundException if the file does not exist. Note that you can call dir.fileExists(name) if you are not sure whether the file exists or not.

      For backwards we'll create a new method w/ clear semantics. Something like:

      /**
       * @deprecated the method will become abstract when #fileLength(name) has been removed.
       */
      public long getFileLength(String name) throws IOException {
        long len = fileLength(name);
        if (len == 0 && !fileExists(name)) {
          throw new FileNotFoundException(name);
        }
        return len;
      }
      

      The first line just calls the current impl. If it throws exception for a non-existing file, we're ok. The second line verifies whether a 0 length is for an existing file or not and throws an exception appropriately.

        Attachments

          Activity

            People

            • Assignee:
              shaie Shai Erera
              Reporter:
              shaie Shai Erera
            • Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

              • Created:
                Updated:
                Resolved: