Interface StreamLogScan

All Superinterfaces:
LogScan
All Known Implementing Classes:
FlushedScan, Scan

public interface StreamLogScan extends LogScan
LogScan provides methods to read a log record and get its LogInstant in an already defined scan. A logscan also needs to know how to advance to the next log record.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    Close this log scan.
    long
    Get the instant of the record just retrieved with getNextRecord().
    Get the LogInstant for the record just retrieved with getNextRecord().
    long
    Get the log instant that is right after the record just retrieved with getNextRecord().
    getNextRecord(ArrayInputStream input, TransactionId tranId, int groupmask)
    Get the next record in the scan and place its data in the passed in array.
    boolean
     
    void
    Reset the scan to the given LogInstant so that getNextRecord get the log record AFTER the given LogInstant.
  • Method Details

    • getNextRecord

      LogRecord getNextRecord(ArrayInputStream input, TransactionId tranId, int groupmask) throws StandardException, IOException
      Get the next record in the scan and place its data in the passed in array. The scan is advanced to the next log record. If the input array is of insufficient size, getNextRecord must expand the array to accomodate the log record. User can optionally pass in a transaction Id and a group mask. If provided, only log record that matches the transaction Id and the group mask is returned.
      Parameters:
      input - the ArrayInputStream to put the log record
      tranId - if non-null, only log record that equals tranId will be returned. If null, log records are not filtered on transaction Id.
      groupmask - if non-zero, only log record whose Loggable's group value is included in the groupmask is returned. groupmask can be a bit wise OR of many Loggable groups. If zero, log records are not filtered on the Loggable's group.
      Returns:
      an object that represents the log record, return null if the scan has completed.
      Throws:
      StandardException - Standard Clooudscape error policy
      IOException - Some I/O exception raised during reading the log record.
    • getInstant

      long getInstant()
      Get the instant of the record just retrieved with getNextRecord().
      Returns:
      INVALID_LOG_INSTANT if no records have been returned yet or the scan has completed.
    • getLogRecordEnd

      long getLogRecordEnd()
      Get the log instant that is right after the record just retrieved with getNextRecord(). Only valid for a forward scan and on a successful retrieval.
      Returns:
      INVALID_LOG_INSTANT if this is not a FORWARD scan or, no record have been returned yet or the scan has completed.
    • isLogEndFuzzy

      boolean isLogEndFuzzy()
      Returns:
      true if fuzzy log end found during forward scan, this happens if there was a partially written log records before the crash.
    • getLogInstant

      LogInstant getLogInstant()
      Get the LogInstant for the record just retrieved with getNextRecord().
      Returns:
      null if no records have been returned yet or the scan has completed.
    • resetPosition

      void resetPosition(LogInstant instant) throws IOException, StandardException
      Reset the scan to the given LogInstant so that getNextRecord get the log record AFTER the given LogInstant.
      Parameters:
      instant - the log instant to reset to
      Throws:
      IOException - Some I/O exception raised when accessing the log file
      StandardException - reset to illegal position or beyond the limit of the scan.
    • close

      void close()
      Close this log scan.