[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - Re: Journal Clean up / Compactor

[clebert.suconic@jboss.com]

This is a summary of the main changes:


- JournalFile..
I have added:


  |    void addCleanupInfo(long id, JournalFile deleteFile);
  |    JournalFile getCleanupInfo(long id);
  |  

I need to know what records are possibly bad. If a delete happened on a different file, I need that information to later perform a delete. The cleanupInfo will give me that List.


On JournalImpl, when a record is deleted, if the record is on a different file, I add the Information on that list:


  | inner class PosFiles:
  | ...
  | 
  |       void addDelete(final long id, final JournalFile deleteFile)
  |       {
  |          if (addFile != deleteFile)
  |          {
  |             addFile.addCleanupInfo(id, deleteFile);
  |          } 
  | 
  |          deleteFile.incNegCount(addFile);
  | 
  |          if (updateFiles != null)
  |          {
  |             for (JournalFile updateF : updateFiles)
  |             {
  |                if (addFile != updateF)
  |                {
  | 
  |                   // ... (some comments suppressed here)
  |                   updateF.addCleanupInfo(id, deleteFile);
  |                }
  | 
  |                deleteFile.incNegCount(updateF);
  |             }
  |          }
  |       }
  | 


During the cleanup, if a record is on that list, I change the field-type for that record as CLEARED. 


         readJournalFile(journalFile, new JournalReader()
  |          {
  | 
  |             public void addRecord(final int recordPos, final RecordInfo recordInfo) throws Exception
  |             {
  |                JournalFile cleanupFile = journalFile.getCleanupInfo(recordInfo.id);
  |                if (cleanupFile != null)
  |                {
  |                   if (trace)
  |                   {
  |                      trace("Cleaning addRecord id = " + recordInfo.id);
  |                   }
  | 
  |                   ByteBufferWrapper buffer = generateAddRecord(false,
  |                                                                fileID,
  |                                                                recordInfo.id,
  |                                                                recordInfo.userRecordType,
  |                                                                new ByteArrayEncoding(recordInfo.data));
  | 
  |                   buffer.rewind();
  | 
  |                   sf.position(recordPos);
  |                   sf.write(buffer.getBuffer(), false);
  | 
  |                   // Eliminating the dependency between a and b
  | 
  |                   cleanupFile.decNegCount(journalFile);
  |                   journalFile.decPosCount();
  |                }
  | 
  |             }
  | 



And to support reading JournalFiles for different purposes other than loading, I have created a method readJournalFile, that will be used by both load, cleaning, and compacting (in the future). The logic of reading the file is kept on a single place:



  |    // Used by both load, cleanup, and compact (in future)
  |    private int readJournalFile(final JournalFile file, final JournalReader reader) throws Exception
  |    {
  | 

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