com.sleepycat.db
Class DbLogc

java.lang.Object
  |
  +--com.sleepycat.db.DbLogc

public class DbLogc

extends Object

The DbLogc object is the handle for a cursor into the log files, supporting sequential access to the records stored in log files. The handle is not free-threaded. Once the DbLogc.close method is called, the handle may not be accessed again, regardless of that method's return.

Method Summary

void	close(int flags) The DbLogc.close method discards the log cursor.
int	get(DbLsn lsn, Dbt data, int flags) The DbLogc.get method returns records from the log.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

close

public void close(int flags)
           throws DbException

The DbLogc.close method discards the log cursor. After DbLogc.close has been called, regardless of its return, the cursor handle may not be used again.

Parameters:

flags - currently unused, and must be set to 0.

Throws:

DbException

IllegalArgumentException - The DbLogc.close method will fail and throw a IllegalArgumentException exception if the cursor was previously closed; or if an invalid flag value or parameter was specified.

get

public int get(DbLsn lsn,
               Dbt data,
               int flags)
        throws DbException

The DbLogc.get method returns records from the log.

Parameters:

data - The data field of the data structure is set to the record retrieved, and the size field indicates the number of bytes in the record. See Dbt for a description of other fields in the data structure. The Db.DB_DBT_MALLOC, Db.DB_DBT_REALLOC and Db.DB_DBT_USERMEM flags may be specified for any Dbt used for data retrieval.

flags - must be set to one of the following values:

• Db.DB_CURRENT

  Return the log record to which the log currently refers.

• Db.DB_FIRST

  The first record from any of the log files found in the log directory is returned in the data parameter. overwritten with the DbLsn of the record returned.

• Db.DB_LAST

  The last record in the log is returned in the data parameter. overwritten with the DbLsn of the record returned.

• Db.DB_NEXT

  The current log position is advanced to the next record in the log, and that record is returned in the data parameter. overwritten with the DbLsn of the record returned.

  If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc.get will return the first record in the log.

• Db.DB_PREV

  The current log position is advanced to the previous record in the log, and that record is returned in the data parameter. overwritten with the DbLsn of the record returned.

  If the cursor has not been initialized via DB_FIRST, DB_LAST, DB_SET, DB_NEXT, or DB_PREV, DbLogc.get will return the last record in the log.

• Db.DB_SET

  Retrieve the record specified by the lsn parameter.

lsn - When the flag parameter is set to Db.DB_CURRENT, Db.DB_FIRST, Db.DB_LAST, Db.DB_NEXT or Db.DB_PREV, the lsn parameter is overwritten with the DbLsn value of the record retrieved. When flag is set to Db.DB_SET, the lsn parameter is the DbLsn value of the record to be retrieved.

Returns:

Unless otherwise specified, the DbLogc.get method throws an exception that encapsulates a non-zero error value on failure.

• DB_NOTFOUND

  The DbLogc.get method will return Db.DB_NOTFOUND if Db.DB_FIRST is set and the log is empty.

• DB_NOTFOUND

  The DbLogc.get method will return Db.DB_NOTFOUND if Db.DB_LAST is set and the log is empty.

• DB_NOTFOUND

  The DbLogc.get method will return Db.DB_NOTFOUND if Db.DB_NEXT is set and the last log record has already been returned or the log is empty.

• DB_NOTFOUND

  The DbLogc.get method will return Db.DB_NOTFOUND if Db.DB_PREV is set and the first log record has already been returned or the log is empty.

Throws:

DbException

IllegalArgumentException - The DbLogc.get method will fail and throw a IllegalArgumentException exception if the Db.DB_CURRENT flag was set and the log cursor has not yet been initialized; the Db.DB_CURRENT, Db.DB_NEXT, or Db.DB_PREV flags were set and the log was opened with the DB_THREAD flag set; the Db.DB_SET flag was set and the specified log sequence number does not appear in the log; or if an invalid flag value or parameter was specified.