/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper.server.persistence;
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.jute.Record;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.KeeperException.Code;
import org.apache.zookeeper.ZooDefs.OpCode;
import org.apache.zookeeper.server.DataTree;
import org.apache.zookeeper.server.DataTree.ProcessTxnResult;
import org.apache.zookeeper.server.Request;
import org.apache.zookeeper.server.ZooTrace;
import org.apache.zookeeper.server.persistence.TxnLog.TxnIterator;
import org.apache.zookeeper.txn.CreateSessionTxn;
import org.apache.zookeeper.txn.CreateTxn;
import org.apache.zookeeper.txn.TxnHeader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This is a helper class
* above the implementations
* of txnlog and snapshot
* classes
*/
public class FileTxnSnapLog {
//the direcotry containing the
//the transaction logs
File dataDir;
//the directory containing the
//the snapshot directory
File snapDir;
TxnLog txnLog;
SnapShot snapLog;
public final static int VERSION = 2;
public final static String version = "version-";
private static final Logger LOG = LoggerFactory.getLogger(FileTxnSnapLog.class);
/**
* This listener helps
* the external apis calling
* restore to gather information
* while the data is being
* restored.
*/
public interface PlayBackListener {
void onTxnLoaded(TxnHeader hdr, Record rec);
}
/**
* the constructor which takes the datadir and
* snapdir.
* @param dataDir the trasaction directory
* @param snapDir the snapshot directory
*/
public FileTxnSnapLog(File dataDir, File snapDir) throws IOException {
this.dataDir = new File(dataDir, version + VERSION);
this.snapDir = new File(snapDir, version + VERSION);
if (!this.dataDir.exists()) {
if (!this.dataDir.mkdirs()) {
throw new IOException("Unable to create data directory "
+ this.dataDir);
}
}
if (!this.snapDir.exists()) {
if (!this.snapDir.mkdirs()) {
throw new IOException("Unable to create snap directory "
+ this.snapDir);
}
}
txnLog = new FileTxnLog(this.dataDir);
snapLog = new FileSnap(this.snapDir);
}
/**
* get the datadir used by this filetxn
* snap log
* @return the data dir
*/
public File getDataDir() {
return this.dataDir;
}
/**
* get the snap dir used by this
* filetxn snap log
* @return the snap dir
*/
public File getSnapDir() {
return this.snapDir;
}
/**
* this function restores the server
* database after reading from the
* snapshots and transaction logs
* @param dt the datatree to be restored
* @param sessions the sessions to be restored
* @param listener the playback listener to run on the
* database restoration
* @return the highest zxid restored
* @throws IOException
*/
public long restore(DataTree dt, Map<Long, Integer> sessions,
PlayBackListener listener) throws IOException {
snapLog.deserialize(dt, sessions);
FileTxnLog txnLog = new FileTxnLog(dataDir);
TxnIterator itr = txnLog.read(dt.lastProcessedZxid+1);
long highestZxid = dt.lastProcessedZxid;
TxnHeader hdr;
while (true) {
// iterator points to
// the first valid txn when initialized
hdr = itr.getHeader();
if (hdr == null) {
//empty logs
return dt.lastProcessedZxid;
}
if (hdr.getZxid() < highestZxid && highestZxid != 0) {
LOG.error(highestZxid + "(higestZxid) > "
+ hdr.getZxid() + "(next log) for type "
+ hdr.getType());
} else {
highestZxid = hdr.getZxid();
}
try {
processTransaction(hdr,dt,sessions, itr.getTxn());
} catch(KeeperException.NoNodeException e) {
throw new IOException("Failed to process transaction type: " +
hdr.getType() + " error: " + e.getMessage());
}
listener.onTxnLoaded(hdr, itr.getTxn());
if (!itr.next())
break;
}
return highestZxid;
}
/**
* process the transaction on the datatree
* @param hdr the hdr of the transaction
* @param dt the datatree to apply transaction to
* @param sessions the sessions to be restored
* @param txn the transaction to be applied
*/
public void processTransaction(TxnHeader hdr,DataTree dt,
Map<Long, Integer> sessions, Record txn)
throws KeeperException.NoNodeException {
ProcessTxnResult rc;
switch (hdr.getType()) {
case OpCode.createSession:
sessions.put(hdr.getClientId(),
((CreateSessionTxn) txn).getTimeOut());
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,ZooTrace.SESSION_TRACE_MASK,
"playLog --- create session in log: "
+ Long.toHexString(hdr.getClientId())
+ " with timeout: "
+ ((CreateSessionTxn) txn).getTimeOut());
}
// give dataTree a chance to sync its lastProcessedZxid
rc = dt.processTxn(hdr, txn);
break;
case OpCode.closeSession:
sessions.remove(hdr.getClientId());
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,ZooTrace.SESSION_TRACE_MASK,
"playLog --- close session in log: "
+ Long.toHexString(hdr.getClientId()));
}
rc = dt.processTxn(hdr, txn);
break;
default:
rc = dt.processTxn(hdr, txn);
}
/**
* Snapshots are taken lazily. It can happen that the child
* znodes of a parent are created after the parent
* is serialized. Therefore, while replaying logs during restore, a
* create might fail because the node was already
* created.
*
* After seeing this failure, we should increment
* the cversion of the parent znode since the parent was serialized
* before its children.
*
* Note, such failures on DT should be seen only during
* restore.
*/
if (hdr.getType() == OpCode.create &&
rc.err == Code.NODEEXISTS.intValue()) {
LOG.debug("Adjusting parent cversion for Txn: " + hdr.getType() +
" path:" + rc.path + " err: " + rc.err);
int lastSlash = rc.path.lastIndexOf('/');
String parentName = rc.path.substring(0, lastSlash);
CreateTxn cTxn = (CreateTxn)txn;
try {
dt.setCversionPzxid(parentName, cTxn.getParentCVersion(),
hdr.getZxid());
} catch (KeeperException.NoNodeException e) {
LOG.error("Failed to set parent cversion for: " +
parentName, e);
throw e;
}
} else if (rc.err != Code.OK.intValue()) {
LOG.debug("Ignoring processTxn failure hdr: " + hdr.getType() +
" : error: " + rc.err);
}
}
/**
* the last logged zxid on the transaction logs
* @return the last logged zxid
*/
public long getLastLoggedZxid() {
FileTxnLog txnLog = new FileTxnLog(dataDir);
return txnLog.getLastLoggedZxid();
}
/**
* save the datatree and the sessions into a snapshot
* @param dataTree the datatree to be serialized onto disk
* @param sessionsWithTimeouts the sesssion timeouts to be
* serialized onto disk
* @throws IOException
*/
public void save(DataTree dataTree,
ConcurrentHashMap<Long, Integer> sessionsWithTimeouts)
throws IOException {
long lastZxid = dataTree.lastProcessedZxid;
LOG.info("Snapshotting: " + Long.toHexString(lastZxid));
File snapshot=new File(
snapDir, Util.makeSnapshotName(lastZxid));
snapLog.serialize(dataTree, sessionsWithTimeouts, snapshot);
}
/**
* truncate the transaction logs the zxid
* specified
* @param zxid the zxid to truncate the logs to
* @return true if able to truncate the log, false if not
* @throws IOException
*/
public boolean truncateLog(long zxid) throws IOException {
FileTxnLog txnLog = new FileTxnLog(dataDir);
return txnLog.truncate(zxid);
}
/**
* the most recent snapshot in the snapshot
* directory
* @return the file that contains the most
* recent snapshot
* @throws IOException
*/
public File findMostRecentSnapshot() throws IOException {
FileSnap snaplog = new FileSnap(snapDir);
return snaplog.findMostRecentSnapshot();
}
/**
* the n most recent snapshots
* @param n the number of recent snapshots
* @return the list of n most recent snapshots, with
* the most recent in front
* @throws IOException
*/
public List<File> findNRecentSnapshots(int n) throws IOException {
FileSnap snaplog = new FileSnap(snapDir);
return snaplog.findNRecentSnapshots(n);
}
/**
* get the snapshot logs that are greater than
* the given zxid
* @param zxid the zxid that contains logs greater than
* zxid
* @return
*/
public File[] getSnapshotLogs(long zxid) {
return FileTxnLog.getLogFiles(dataDir.listFiles(), zxid);
}
/**
* append the request to the transaction logs
* @param si the request to be appended
* returns true iff something appended, otw false
* @throws IOException
*/
public boolean append(Request si) throws IOException {
return txnLog.append(si.hdr, si.txn);
}
/**
* commit the transaction of logs
* @throws IOException
*/
public void commit() throws IOException {
txnLog.commit();
}
/**
* roll the transaction logs
* @throws IOException
*/
public void rollLog() throws IOException {
txnLog.rollLog();
}
/**
* close the transaction log files
* @throws IOException
*/
public void close() throws IOException {
txnLog.close();
snapLog.close();
}
}