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 Detail

      • getNextRecord

        LogRecord getNextRecord​(ArrayInputStream input,
                                TransactionId tranId,
                                int groupmask)
                         throws StandardException,
                                java.io.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
        java.io.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 java.io.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:
        java.io.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.