/*
* A checksum error has been encountered. Go to the start of this log file
* and read forward until the lower side of the corrupted area has been
* found.
*/
@Override
protected boolean resyncReader(long nextGoodRecordPostCorruption, boolean showCorruptedBounds)
throws DatabaseException {
LastFileReader reader = null;
long tryReadBufferFileNum = DbLsn.getFileNumber(nextGoodRecordPostCorruption);
while (tryReadBufferFileNum >= 0) {
try {
reader = new LastFileReader(envImpl, readBufferSize, Long.valueOf(tryReadBufferFileNum));
break;
} catch (ChecksumException e) {
/*
* We encountered a problem opening this file so skip to an
* earlier file.
*/
tryReadBufferFileNum--;
continue;
}
}
boolean switchedFiles =
tryReadBufferFileNum != DbLsn.getFileNumber(nextGoodRecordPostCorruption);
if (!switchedFiles) {
/*
* Read forward until a checksum fails. This reader will not throw
* an exception if a checksum error is hit -- it will just return
* false.
*/
while (reader.readNextEntry()) {}
}
long lastUsedLsn = reader.getLastValidLsn();
long nextAvailableLsn = reader.getEndOfLog();
if (showCorruptedBounds) {
System.err.println("A checksum error was found in the log.");
System.err.println("Corruption begins at LSN:\n " + DbLsn.toString(nextAvailableLsn));
System.err.println(
"Last known good record before corruption is at LSN:\n " + DbLsn.toString(lastUsedLsn));
System.err.println(
"Next known good record after corruption is at LSN:\n "
+ DbLsn.toString(nextGoodRecordPostCorruption));
}
startLsn = lastUsedLsn;
initStartingPosition(nextAvailableLsn, null);
if (switchedFiles) {
currentEntryPrevOffset = 0;
}
/* Indicate resync is permitted so don't throw exception. */
return true;
}
/**
* readNextEntry will stop at a bad entry.
*
* @return true if an element has been read.
*/
public boolean readNextEntry() throws DatabaseException, IOException {
boolean foundEntry = false;
try {
/*
* At this point,
* currentEntryOffset is the entry we just read.
* nextEntryOffset is the entry we're about to read.
* currentEntryPrevOffset is 2 entries ago.
* Note that readNextEntry() moves all the offset pointers up.
*/
foundEntry = super.readNextEntry();
/*
* Note that initStartingPosition() makes sure that the file header
* entry is valid. So by the time we get to this method, we know
* we're at a file with a valid file header entry.
*/
lastValidOffset = currentEntryOffset;
nextUnprovenOffset = nextEntryOffset;
} catch (DbChecksumException e) {
Tracer.trace(
Level.INFO,
envImpl,
"Found checksum exception while searching "
+ " for end of log. Last valid entry is at "
+ DbLsn.toString(DbLsn.makeLsn(readBufferFileNum, lastValidOffset))
+ " Bad entry is at "
+ DbLsn.makeLsn(readBufferFileNum, nextUnprovenOffset));
}
return foundEntry;
}
/**
* readNextEntry will stop at a bad entry.
*
* @return true if an element has been read.
*/
@Override
public boolean readNextEntry() {
boolean foundEntry = false;
try {
/*
* At this point,
* currentEntryOffset is the entry we just read.
* nextEntryOffset is the entry we're about to read.
* currentEntryPrevOffset is 2 entries ago.
* Note that readNextEntry() moves all the offset pointers up.
*/
foundEntry = super.readNextEntryAllowExceptions();
/*
* Note that initStartingPosition() makes sure that the file header
* entry is valid. So by the time we get to this method, we know
* we're at a file with a valid file header entry.
*/
lastValidOffset = currentEntryOffset;
nextUnprovenOffset = nextEntryOffset;
} catch (FileNotFoundException e) {
throw new EnvironmentFailureException(
envImpl, EnvironmentFailureReason.LOG_FILE_NOT_FOUND, e);
} catch (ChecksumException e) {
LoggerUtils.fine(
logger,
envImpl,
"Found checksum exception while searching for end of log. "
+ "Last valid entry is at "
+ DbLsn.toString(DbLsn.makeLsn(window.currentFileNum(), lastValidOffset))
+ " Bad entry is at "
+ DbLsn.makeLsn(window.currentFileNum(), nextUnprovenOffset));
}
return foundEntry;
}