com.sleepycat.je.log

Class RestoreMarker

java.lang.Object

com.sleepycat.je.log.RestoreMarker

public class RestoreMarker
extends Object

A RestoreMarker is a file that indicates that a normal recovery is not possible, because the log files are physically or semantically inconsistent in some way. One example is an interrupted, incomplete network restore. The network restore copies log files from a source to destination node. If it's halted, while the destination node may contain files that are readable, checksum-able and seem correct, the set as a whole may not have a complete and coherent copy of the log. In such a case, recovery should not be run on this environment's log until some action is taken to make it consistent. For a network restore, this curative action is to restart the copy process, and to complete the copy of a set of logs from some node to this node. The network restore creates a marker file just before it does any form of change to the log that would make the log inconsistent. The restore marker file is named MAXINT.jdb, and holds a normal log file header and a RestoreRequired log entry. The RestoreRequired entry indicates the type of error of the initial cause, and information needed to repair the environment. The mechanism depends on the fact that the very first step of recovery is to read backwards from the last file in the environment. Recovery will start at this file, and will fail when it reads the RestoreRequired log entry, throwing an exception that contains prescriptive information for how the environment can be repaired. Note that createMarkerFile() is idempotent and can be safely called multiple times. It's done that way to make it simpler for the caller. The handler that repairs the log must also delete the marker file so future recoveries can succeed.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	RestoreMarker.FileCreationException Internal exception used to distinguish marker file creation from other IOErrors.

Constructor Summary

Constructors

Constructor and Description
RestoreMarker(FileManager fileManager, LogManager logManager)

Method Summary

Modifier and Type	Method and Description
void	createMarkerFile(RestoreRequired.FailureType failureType, Properties props) Create the restore marker file.
static String	getMarkerFileName()
void	removeMarkerFile(FileManager fileManager) Remove the marker file.

Methods inherited from class java.lang.Object

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

Constructor Detail

RestoreMarker

public RestoreMarker(FileManager fileManager,
                     LogManager logManager)

Method Detail

getMarkerFileName

public static String getMarkerFileName()

removeMarkerFile

public void removeMarkerFile(FileManager fileManager)
                      throws IOException

Remove the marker file. Use FileManager.delete so this file works with the FileDeletionDetector.

Throws:

IOException - if the file won't delete.

createMarkerFile

public void createMarkerFile(RestoreRequired.FailureType failureType,
                             Properties props)
                      throws RestoreMarker.FileCreationException

Create the restore marker file. The method may be called repeatedly, but will not re-create the marker file if there's already a non-zero length file.

Parameters:

failureType - the failure type that should be recorded in the RestoreRequired log entry.

props - will be serialized to store information about how to handle the failure type.

Throws:

RestoreMarker.FileCreationException - if the marker file can't be created.