/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002-2010 Oracle. All rights reserved.
*
*/
package com.sleepycat.je.rep.stream;
import static com.sleepycat.je.utilint.DbLsn.NULL_LSN;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.logging.Level;
import java.util.logging.Logger;
import com.sleepycat.je.DatabaseException;
import com.sleepycat.je.EnvironmentFailureException;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.log.LogEntryType;
import com.sleepycat.je.log.entry.LogEntry;
import com.sleepycat.je.recovery.CheckpointEnd;
import com.sleepycat.je.rep.impl.node.NameIdPair;
import com.sleepycat.je.rep.vlsn.VLSNIndex;
import com.sleepycat.je.rep.vlsn.VLSNRange;
import com.sleepycat.je.txn.TxnCommit;
import com.sleepycat.je.utilint.LoggerUtils;
import com.sleepycat.je.utilint.VLSN;
/**
* The ReplicaSyncupReader scans the log backwards for requested log entries.
* The reader must track whether it has passed a checkpoint, and therefore
* can not used the vlsn index to skip over entries.
*
* The ReplicaSyncupReader is not thread safe, and can only be used
* serially. It will stop at the finishLsn, which should be set using the
* GlobalCBVLSN.
*/
public class ReplicaSyncupReader extends VLSNReader {
/* True if this particular record retrieval is for a syncable record. */
private boolean syncableSearch;
private final LogEntry ckptEndLogEntry =
LogEntryType.LOG_CKPT_END.getNewLogEntry();
private final LogEntry commitLogEntry =
LogEntryType.LOG_TXN_COMMIT.getNewLogEntry();
/*
* SearchResults retains the information as to whether the found
* matchpoint is valid.
*/
private final MatchpointSearchResults searchResults;
private final Logger logger;
public ReplicaSyncupReader(EnvironmentImpl envImpl,
VLSNIndex vlsnIndex,
long endOfLogLsn,
int readBufferSize,
NameIdPair nameIdPair,
VLSN startVLSN,
long finishLsn,
MatchpointSearchResults searchResults)
throws IOException, DatabaseException {
/*
* If we go backwards, endOfFileLsn and startLsn must not be null.
* Make them the same, so we always start at the same very end.
*/
super(envImpl,
vlsnIndex,
false, // forward
endOfLogLsn,
readBufferSize,
nameIdPair,
finishLsn);
initScan(startVLSN, endOfLogLsn);
this.searchResults = searchResults;
logger = LoggerUtils.getLogger(getClass());
}
/**
* Set up the ReplicaSyncupReader to start scanning from this VLSN.
* @throws IOException
*/
private void initScan(VLSN startVLSN, long endOfLogLsn)
throws IOException {
if (startVLSN.equals(VLSN.NULL_VLSN)) {
throw EnvironmentFailureException.unexpectedState
("ReplicaSyncupReader start can't be NULL_VLSN");
}
startLsn = endOfLogLsn;
assert startLsn != NULL_LSN;
/*
* Flush the log so that syncup can assume that all log entries that
* are represented in the VLSNIndex are safely out of the log buffers
* and on disk. Simplifies this reader, so it can use the regular
* ReadWindow, which only works on a file.
*/
envImpl.getLogManager().flush();
window.initAtFileStart(startLsn);
currentEntryPrevOffset = window.getEndOffset();
currentEntryOffset = window.getEndOffset();
currentVLSN = startVLSN;
}
/**
* Backward scanning for the replica's part in syncup.
*/
public OutputWireRecord scanBackwards(VLSN vlsn)
throws DatabaseException {
syncableSearch = false;
VLSNRange range = vlsnIndex.getRange();
if (vlsn.compareTo(range.getFirst()) < 0) {
/*
* The requested VLSN is before the start of our range, we don't
* have this record.
*/
return null;
}
currentVLSN = vlsn;
if (readNextEntry()) {
return currentFeedRecord;
}
return null;
}
/**
* Backward scanning for finding an earlier candidate syncup matchpoint.
*/
public OutputWireRecord findPrevSyncEntry()
throws DatabaseException {
currentFeedRecord = null;
syncableSearch = true;
/* Start by looking at the entry before the current record. */
currentVLSN = currentVLSN.getPrev();
VLSNRange range = vlsnIndex.getRange();
if (currentVLSN.compareTo(range.getFirst()) < 0) {
/*
* We've walked off the end of the contiguous VLSN range.
*/
return null;
}
if (readNextEntry() == false) {
/*
* We scanned all the way to the front of the log, no
* other sync-able entry found.
*/
return null;
}
assert LogEntryType.isSyncPoint(currentFeedRecord.getEntryType()) :
"Unexpected log type= " + currentFeedRecord;
return currentFeedRecord;
}
/**
* @throw an EnvironmentFailureException if we were scanning for a
* particular VLSN and we have passed it by.
*/
private void checkForPassingTarget(int compareResult) {
if (compareResult < 0) {
/* Hey, we passed the VLSN we wanted. */
throw EnvironmentFailureException.unexpectedState
("want to read " + currentVLSN + " but reader at " +
currentEntryHeader.getVLSN());
}
}
/**
* Return true for ckpt entries, for syncable entries, and if we're in
* specific vlsn scan mode, any replicated entry. There is an additional
* level of filtering in processEntry.
*/
@Override
protected boolean isTargetEntry()
throws DatabaseException {
if (logger.isLoggable(Level.FINEST)) {
LoggerUtils.finest(logger, envImpl,
" isTargetEntry " + currentEntryHeader);
}
nScanned++;
/* Skip invisible entries. */
if (currentEntryHeader.isInvisible()) {
return false;
}
byte currentType = currentEntryHeader.getType();
/*
* Return true if this entry is replicated. All entries need to be
* perused by processEntry, when we are doing a vlsn based search,
* even if they are not a sync point, because:
* (a) If this is a vlsn-based search, it's possible that the replica
* and feeder are mismatched. The feeder will only propose a sync type
* entry as a matchpoint but it might be that the replica has a non-
* sync entry at that vlsn.
* (b) We need to note passed commits in processEntry.
*/
if (entryIsReplicated()) {
if (syncableSearch) {
if (LogEntryType.isSyncPoint(currentType)) {
return true;
}
currentVLSN = currentEntryHeader.getVLSN().getPrev();
} else {
return true;
}
}
/*
* We'll also need to read checkpoint end records to record their
* presence.
*/
if (LogEntryType.LOG_CKPT_END.equalsType(currentType)) {
return true;
}
return false;
}
/**
* ProcessEntry does additional filtering before deciding whether to
* return an entry as a candidate for matching.
*
* If this is a record we are submitting as a matchpoint candidate,
* instantiate a WireRecord to house this log entry. If this is a
* non-replicated entry or a txn end that follows the candidate matchpoint,
* record whatever status we need to, but don't use it for comparisons.
*
* For example, suppose the log is like this:f
*
* VLSN entry
* 10 LN
* 11 commit
* 12 LN
* -- ckpt end
* 13 commit
* 14 abort
*
* And that the master only has VLSNs 1-12. The replica will suggest vlsn
* 14 as the first matchpoint. The feeder will counter with a suggestion
* of vlsn 11, since it doe not have vlsn 14.
*
* At that point, the ReplicaSyncupReader will scan backwards in the log,
* looking for vlsn 11. Although the reader should only return an entry
* when it gets to vlsn 11. the reader must process commits and ckpts that
* follow 11, so that they can be recorded in the searchResults, so the
* number of rolled back commits can be accurately reported.
*/
@Override
protected boolean processEntry(ByteBuffer entryBuffer) {
if (logger.isLoggable(Level.FINEST)) {
LoggerUtils.finest(logger, envImpl,
" syncup reader saw " + currentEntryHeader);
}
byte currentType = currentEntryHeader.getType();
/*
* CheckpointEnd entries are tracked in order to see if a rollback
* must be done, but are not returned as possible matchpoints.
*/
if (LogEntryType.LOG_CKPT_END.equalsType(currentType)) {
/*
* Read the entry, which both lets us decipher its contents and
* also advances the file reader position.
*/
ckptEndLogEntry.readEntry(currentEntryHeader, entryBuffer,
true /*readFullItem*/);
if (logger.isLoggable(Level.FINEST)) {
LoggerUtils.finest(logger, envImpl,
" syncup reader read " +
currentEntryHeader + ckptEndLogEntry);
}
if (((CheckpointEnd) ckptEndLogEntry.getMainItem()).
getCleanedFilesToDelete()) {
searchResults.notePassedCheckpointEnd();
}
return false;
}
/*
* Setup the log entry as a wire record so we can compare it to
* the entry from the feeder as we look for a matchpoint. Do this
* before we change positions on the entry buffer by reading it.
*/
ByteBuffer buffer = entryBuffer.slice();
buffer.limit(currentEntryHeader.getItemSize());
currentFeedRecord = new OutputWireRecord(currentEntryHeader, buffer);
/*
* All commit records must be tracked to figure out if we've exceeded
* the txn rollback limit. For reporting reasons, we'll need to
* unmarshal the log entry, so we can read the timestamp in the commit
* record.
*/
if (LogEntryType.LOG_TXN_COMMIT.equalsType(currentType)) {
commitLogEntry.readEntry(currentEntryHeader, entryBuffer,
true /*readFullItem*/);
TxnCommit commit = (TxnCommit) commitLogEntry.getMainItem();
searchResults.notePassedCommits(commit.getTime(),
commit.getId(),
currentEntryHeader.getVLSN(),
getLastLsn());
if (logger.isLoggable(Level.FINEST)) {
LoggerUtils.finest(logger, envImpl,
"syncup reader read " +
currentEntryHeader + commitLogEntry);
}
} else {
entryBuffer.position(entryBuffer.position() +
currentEntryHeader.getItemSize());
}
if (syncableSearch) {
return true;
}
/* We're looking for a particular VLSN. */
int compareResult = currentEntryHeader.getVLSN().compareTo(currentVLSN);
checkForPassingTarget(compareResult);
/* return true if this is the entry we want. */
return (compareResult == 0);
}
}