com.sleepycat.je.log

Class ScavengerFileReader

java.lang.Object

com.sleepycat.je.log.FileReader

com.sleepycat.je.log.ScavengerFileReader

public abstract class ScavengerFileReader
extends FileReader

A ScavengerFileReader reads the log backwards. If it encounters a checksum error, it goes to the start of that log file and reads forward until it encounters a checksum error. It then continues the reading backwards in the log. The caller may set "dumpCorruptedBounds" to true if information about the start and finish of the corrupted portion should be displayed on stderr. The caller is expected to implement processEntryCallback. This method is called once for each entry that the ScavengerFileReader finds in the log.

Nested Class Summary

Nested classes/interfaces inherited from class com.sleepycat.je.log.FileReader

FileReader.EOFException, FileReader.ReadWindow

Field Summary

Fields inherited from class com.sleepycat.je.log.FileReader

cksumValidator, currentEntryHeader, currentEntryOffset, currentEntryPrevOffset, envImpl, eof, fileManager, forward, logger, nextEntryOffset, startLsn, window

Constructor Summary

Constructors

Constructor and Description
ScavengerFileReader(EnvironmentImpl env, int readBufferSize, long startLsn, long finishLsn, long endOfFileLsn) Create this reader to start at a given LSN.

Method Summary

Modifier and Type	Method and Description
protected void	handleGapInBackwardsScan(long prevFileNum) TBW
protected boolean	isTargetEntry() This method is called by readNextEntry() after the header of the current logrec has been de-serialized, but not the body.
protected boolean	processEntry(ByteBuffer entryBuffer) Each file reader implements this method to process the entry data.
protected abstract void	processEntryCallback(LogEntry entry, LogEntryType entryType)
boolean	readNextEntry() Scans the log files until either it has reached the end of the log or has hit an invalid portion.
protected boolean	resyncReader(long nextGoodRecordPostCorruption, boolean showCorruptedBounds)
void	setDumpCorruptedBounds(boolean dumpCorruptedBounds) Set to true if corrupted boundaries should be dumped to stderr.
void	setTargetType(LogEntryType type) Tell the reader that we are interested in these kind of entries.

Methods inherited from class com.sleepycat.je.log.FileReader

entryIsReplicated, getAndResetNReads, getLastEntrySize, getLastLsn, getLastVlsn, getLogVersion, getNRepeatIteratorReads, getNumRead, initStartingPosition, makeWindow, readNextEntryAllowExceptions, setAlwaysValidateChecksum, setBackwardPosition, setForwardPosition, skipData, skipEntry

Methods inherited from class java.lang.Object

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

Constructor Detail

ScavengerFileReader

public ScavengerFileReader(EnvironmentImpl env,
                           int readBufferSize,
                           long startLsn,
                           long finishLsn,
                           long endOfFileLsn)
                    throws DatabaseException

Create this reader to start at a given LSN.

Throws:

DatabaseException

Method Detail

setDumpCorruptedBounds

public void setDumpCorruptedBounds(boolean dumpCorruptedBounds)

Set to true if corrupted boundaries should be dumped to stderr.

setTargetType

public void setTargetType(LogEntryType type)

Tell the reader that we are interested in these kind of entries.

processEntry

protected boolean processEntry(ByteBuffer entryBuffer)
                        throws DatabaseException

Description copied from class: FileReader

Each file reader implements this method to process the entry data.

Specified by:

processEntry in class FileReader

Parameters:

entryBuffer - A ByteBuffer that the logrec data and is positioned at the start of the logrec body (i.e., just after the logrec header).

Returns:

true if this entry should be returned to the caller of readNextEntry().

Throws:

DatabaseException

processEntryCallback

protected abstract void processEntryCallback(LogEntry entry,
                                             LogEntryType entryType)
                                      throws DatabaseException

Throws:

DatabaseException

readNextEntry

public boolean readNextEntry()

Description copied from class: FileReader

Scans the log files until either it has reached the end of the log or has hit an invalid portion.

Overrides:

readNextEntry in class FileReader

Returns:

true if an element has been read, false at end-of-log.

handleGapInBackwardsScan

protected void handleGapInBackwardsScan(long prevFileNum)

TBW

Overrides:

handleGapInBackwardsScan in class FileReader

resyncReader

protected boolean resyncReader(long nextGoodRecordPostCorruption,
                               boolean showCorruptedBounds)
                        throws DatabaseException

Throws:

DatabaseException

isTargetEntry

protected boolean isTargetEntry()

Description copied from class: FileReader

This method is called by readNextEntry() after the header of the current logrec has been de-serialized, but not the body. Based on header info only, it may perform some actions and then decide whether the rest of the logrec should be de-serialized or just skipped.

Overrides:

isTargetEntry in class FileReader

Returns:

true if this reader should process this entry, or just skip over it.