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java.lang.Objectorg.exist.storage.journal.JournalReader
Read log entries from the journal file. This class is used during recovery to scan the last journal file. It uses a memory-mapped byte buffer on the file. Journal entries can be read forward (during redo) or backward (during undo).
Constructor Summary | |
JournalReader(DBBroker broker,
java.io.File file,
int fileNumber)
Opens the specified file for reading. |
Method Summary | |
void |
close()
|
Loggable |
lastEntry()
|
Loggable |
nextEntry()
Returns the next entry found from the current position. |
void |
position(long lsn)
Re-position the file position so it points to the start of the entry with the given LSN. |
Loggable |
previousEntry()
Returns the previous entry found by scanning backwards from the current position. |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public JournalReader(DBBroker broker, java.io.File file, int fileNumber) throws LogException
broker
- file
- fileNumber
-
LogException
Method Detail |
public Loggable nextEntry() throws LogException
LogException
- if an entry could not be read due to an inconsistency on disk.public Loggable previousEntry() throws LogException
LogException
- if an entry could not be read due to an inconsistency on disk.
java.io.IOException
public Loggable lastEntry() throws LogException
LogException
public void position(long lsn) throws LogException
lsn
-
java.io.IOException
LogException
public void close()
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