Package com.tangosol.io.journal

Class FlashJournalRM.WriterDaemon

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.Daemon
com.tangosol.io.journal.FlashJournalRM.WriterDaemon
All Implemented Interfaces:
Guardable, Runnable
Enclosing class:
FlashJournalRM
protected class FlashJournalRM.WriterDaemon extends Daemon
The WriterDaemon takes the enqueued Buffer objects from the PreparerDaemon, and appends them to a JournalFile.

  • Field Details

    • m_queue

      protected BlockingQueue<Runnable> m_queue
      A Queue of items for this daemon to execute.

    • m_cSingleBlockWrites

      protected long m_cSingleBlockWrites
      The number of blocks written individually.

    • m_cMillisSingleBlockWrites

      protected long m_cMillisSingleBlockWrites
      The number of milliseconds total spent writing blocks individually.

    • m_cMultiBlockWrites

      protected long m_cMultiBlockWrites
      The number of blocks written in groups (as part of a multi-buffer write).

    • m_cMillisMultiBlockWrites

      protected long m_cMillisMultiBlockWrites
      The number of milliseconds total spent writing blocks in groups.

    • m_fPreferSingleBlockWrites

      protected boolean m_fPreferSingleBlockWrites
      Set to true if it becomes apparent that single block writes are preferable.

  • Constructor Details

    • WriterDaemon

      public WriterDaemon()
      Construct a WriterDaemon.

  • Method Details

    • stop

      public void stop()
      Request the daemon to stop. This method will only have an effect if the daemon sub-class respects the value returned from Daemon.isStopping().
      Overrides:
      stop in class Daemon

    • run

      public void run()
      The daemon's implementation method. Override this method to implement a daemon.

      An example implementation is: 

      
   while (!isStopping())
       {
       // do some processing
       // ...

       synchronized (this)
           {
           // wait for notification of more work
           wait();
           }
       }

      Specified by:
      run in interface Runnable
      Specified by:
      run in class Daemon

    • setGuardPolicy

      protected void setGuardPolicy(Guardian guardian, long cTimeoutMillis, float flPctRecover)
      Set the Guardian and policy to guard this Daemon with. The Daemon is registered with the specified Guardian each time the Daemon is started, and is released each time the Daemon is stopped.
      Overrides:
      setGuardPolicy in class Daemon
      Parameters:
      guardian - the Guardian that will be guarding this Daemon
      cTimeoutMillis - the timeout in ms for this Daemon, or 0 for the service guardian timeout
      flPctRecover - the recovery percentage for this Daemon

    • getDescription

      protected String getDescription()
      Format the Daemon attributes into a String for inclusion in the String returned from the Daemon.toString() method.
      Overrides:
      getDescription in class Daemon
      Returns:
      a String listing the attributes of the Daemon

    • isSingleBlockWritePreferred

      public boolean isSingleBlockWritePreferred()
      Determine if the next write should automatically use the "single buffer write" capability of NIO, instead of attempting to use the NIO scatter/gather capability.
      Returns:
      true iff the next write should not attempt to use NIO scatter/gather functionality

    • getBlockWriteCount

      public long getBlockWriteCount()
      Determine the total number of blocks written by this daemon.
      Returns:
      the total number of blocks written by this daemon

    • getSingleBlockWriteCount

      public long getSingleBlockWriteCount()
      Determine the number of blocks written by this daemon using the NIO "single buffer write" functionality.
      Returns:
      the number of NIO individual buffer writes

    • getMultiBlockWriteCount

      public long getMultiBlockWriteCount()
      Determine the number of blocks written by this daemon using the NIO "scatter/gather" functionality. This is not the number of writes, since each write involves multiple blocks being written, one in each buffer.
      Returns:
      the number of NIO scatter/gather buffer writes

    • getAvgBlockWriteMillis

      public int getAvgBlockWriteMillis()
      Determine the average number of milliseconds to write each block.
      Returns:
      the average number of milliseconds to write each block

    • getAvgSingleBlockWriteMillis

      public int getAvgSingleBlockWriteMillis()
      Determine the average number of milliseconds to write each block using the NIO "single buffer write" functionality.
      Returns:
      the average number of milliseconds for NIO individual buffer writes

    • getAvgMultiBlockWriteMillis

      public int getAvgMultiBlockWriteMillis()
      Determine the average number of milliseconds to write each block using the NIO "scatter/gather" functionality.
      Returns:
      the average number of milliseconds for NIO scatter/gather writes

    • enqueueBuffer

      public void enqueueBuffer(FlashJournalRM.JournalFile jrnlfile, FlashJournalRM.Buffer buf, int cbBuffer)
      Notify the writer thread that a buffer needs to be written.
      Parameters:
      jrnlfile - the file to append to
      buf - the buffer to append
      cbBuffer - the number of bytes to append from the buffer

    • notifyFileFull

      public void notifyFileFull(FlashJournalRM.JournalFile jrnlfile)
      Notify the writer thread that a file is done being written to.
      Parameters:
      jrnlfile - the file to append to