/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2002, 2011 Oracle and/or its affiliates. All rights reserved.
*
*/
package com.sleepycat.je.rep.vlsn;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.log.LogEntryHeader;
import com.sleepycat.je.log.LogEntryType;
import com.sleepycat.je.log.entry.LogEntry;
import com.sleepycat.je.log.entry.SingleItemEntry;
import com.sleepycat.je.recovery.VLSNRecoveryProxy;
import com.sleepycat.je.txn.RollbackStart;
import com.sleepycat.je.utilint.DbLsn;
import com.sleepycat.je.utilint.VLSN;
/**
* The VLSNRecoveryTracker is used to as a transient tracker at recovery time.
* It gathers up VLSN->LSN mappings that are in the log, but not persisted to
* the mapping database. It has somewhat different preconditions from the
* parent VLSNTracker which affect the semantics of tracking.
*
* Unlike VLSNTracker, the track() method is guaranteed to be executed in a
* serial fashion. In addition, this tracker needs to "discover" where the
* range for this tracker should start. For example, suppose the on-disk
* VLSNIndex covers VLSNs 25 -> 200. Also, suppose that the recovery portion of
* the log holds VLSNs 190 -> 210 (an overlap of 190 -> 200)
*
* The VLSNIndex will be initialized with a range of 25 -> 200. We want the
* recovery tracker to hold VLSN mappings from 190 -> 210. We don't want it to
* just consult its range to determine where the next bucket starts. If we did
* that, the recovery tracker would start at VLSN 1.
*
* The VLSNRecoveryTracker must account for rollbacks and invisible log
* entries. It has the authorative view of what is in the recovery part of the
* log and will override what is in the on-disk tracker. At merge time, the
* regular VLSNIndex must consult the VLSNRecoveryTracker's notion of what the
* highest VLSN value is.
*
* If we see a RollbackStart, the end of range is abruptly reset back to the
* matchpoint start. If we see non-invisible entries, the end of range may be
* incrementing. For example, suppose the log has:recovery tracker
*
* VLSN 10 tracks 10
* VLSN 11 (invisible) skips
* VLSN 12 (invisible) skips
* VLSN 13 (invisible) skips
* rollback start to VLSN 9 truncates to 9, clear everything
* VLSN 10 tracks 10
* VLSN 11 tracks 11
* VLSN 12 tracks 12
* rollback start to VLSN 11 truncates to 11
*
* Suppose the on-disk VLSNIndex holds mappings for VLSN 1->13. A merge of the
* VLSN index and the recovery tracker would
* 1) truncate any VLSN > than the recovery tracker's high point -- so the
* VLSN index will drop mappings 12, 13
* 2) will replace any VLSN index mappings with those held in the recovery
* tracker.
* The VLSNIndex should map 1 -> 11, with the 10 and 11 mapping provided by the
* recovery tracker.
*/
public final class VLSNRecoveryTracker
extends VLSNTracker implements VLSNRecoveryProxy {
private byte rollbackType;
private VLSN lastMatchpointVLSN = VLSN.NULL_VLSN;
private long lastMatchpointLsn = DbLsn.NULL_LSN;
public VLSNRecoveryTracker(EnvironmentImpl envImpl,
int stride,
int maxMappings,
int maxDistance) {
super(envImpl, stride, maxMappings, maxDistance);
rollbackType = LogEntryType.LOG_ROLLBACK_START.getTypeNum();
}
/* VLSNRecoveryProxy.trackMapping */
public void trackMapping(long lsn,
LogEntryHeader currentEntryHeader,
LogEntry targetLogEntry) {
if (currentEntryHeader.getReplicated() &&
!currentEntryHeader.isInvisible()) {
VLSN vlsn = currentEntryHeader.getVLSN();
track(vlsn, lsn, currentEntryHeader.getType());
} else if (currentEntryHeader.getType() == rollbackType) {
RollbackStart rb =
(RollbackStart) ((SingleItemEntry) targetLogEntry).getMainItem();
lastMatchpointVLSN = rb.getMatchpointVLSN();
lastMatchpointLsn = rb.getMatchpoint();
if (range.getFirst().isNull()) {
return;
}
if (range.getFirst().compareTo(lastMatchpointVLSN) > 0) {
/* Throw away all mappings. */
initEmpty();
return;
}
if (range.getLast().compareTo(lastMatchpointVLSN) <= 0) {
/* Nothing to truncate. */
return;
}
truncateFromTail(lastMatchpointVLSN.getNext(), lastMatchpointLsn);
}
}
public boolean isEmpty() {
return bucketCache.size() == 0;
}
public VLSN getLastMatchpointVLSN() {
return lastMatchpointVLSN;
}
public long getLastMatchpointLsn() {
return lastMatchpointLsn;
}
}