org.apache.zookeeper.server

Class DataTree

java.lang.Object

org.apache.zookeeper.server.DataTree

public class DataTree
extends Object

This class maintains the tree data structure. It doesn't have any networking or client connection code in it so that it can be tested in a stand alone way.

The tree maintains two parallel data structures: a hashtable that maps from full paths to DataNodes and a tree of DataNodes. All accesses to a path is through the hashtable. The tree is traversed only when serializing to disk.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DataTree.ProcessTxnResult
class	DataTree.ZxidDigest A helper class to maintain the digest meta associated with specific zxid.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DIGEST_LOG_INTERVAL
static int	DIGEST_LOG_LIMIT
long	lastProcessedZxid
static int	STAT_OVERHEAD_BYTES over-the-wire size of znode's stat.

Constructor Summary

Constructors

Constructor and Description
DataTree()

Method Summary

Modifier and Type	Method and Description
int	aclCacheSize()
void	addConfigNode() create a /zookeeper/config node for maintaining the configuration (membership and quorum system) info for zookeeper
void	addDigestWatcher(DigestWatcher digestWatcher) Add digest mismatch event handler.
void	addWatch(String basePath, Watcher watcher, int mode)
long	approximateDataSize() Get the size of the nodes based on path and data length.
long	cachedApproximateDataSize()
boolean	compareDigest(TxnHeader header, Record txn, TxnDigest digest) Compares the digest of the tree with the digest present in transaction digest.
void	compareSnapshotDigests(long zxid) Compares the actual tree's digest with that in the snapshot.
boolean	containsWatcher(String path, Watcher.WatcherType type, Watcher watcher)
static void	copyStat(Stat from, Stat to)
static void	copyStatPersisted(StatPersisted from, StatPersisted to)
void	createNode(String path, byte[] data, List<ACL> acl, long ephemeralOwner, int parentCVersion, long zxid, long time) Add a new node to the DataTree.
void	createNode(String path, byte[] data, List<ACL> acl, long ephemeralOwner, int parentCVersion, long zxid, long time, Stat outputStat) Add a new node to the DataTree.
static StatPersisted	createStat(long zxid, long time, long ephemeralOwner) Create a node stat from the given params.
void	deleteNode(String path, long zxid) remove the path from the datatree
void	deserialize(InputArchive ia, String tag)
boolean	deserializeZxidDigest(InputArchive ia, long startZxidOfSnapshot) Deserializing the zxid digest from the input stream and update the digestFromLoadedSnapshot.
void	dumpEphemerals(PrintWriter pwriter) Write a text dump of all the ephemerals in the datatree.
void	dumpWatches(PrintWriter pwriter, boolean byPath) Write a text dump of all the watches on the datatree.
void	dumpWatchesSummary(PrintWriter pwriter) Summary of the watches on the datatree.
List<ACL>	getACL(DataNode node)
List<ACL>	getACL(String path, Stat stat)
int	getAllChildrenNumber(String path)
List<String>	getChildren(String path, Stat stat, Watcher watcher)
Set<String>	getContainers()
byte[]	getData(String path, Stat stat, Watcher watcher)
DataTree.ZxidDigest	getDigestFromLoadedSnapshot()
List<DataTree.ZxidDigest>	getDigestLog() Return all the digests in the historical digest list.
Map<Long,Set<String>>	getEphemerals() Returns a mapping of session ID to ephemeral znodes.
Set<String>	getEphemerals(long sessionId)
int	getEphemeralsCount()
DataTree.ZxidDigest	getLastProcessedZxidDigest()
String	getMaxPrefixWithQuota(String path) If there is a quota set, return the appropriate prefix for that quota Else return null
DataNode	getNode(String path)
int	getNodeCount()
ReferenceCountedACLCache	getReferenceCountedAclCache()
Collection<Long>	getSessions()
long	getTreeDigest()
Set<String>	getTtls()
int	getWatchCount()
WatchesReport	getWatches() Returns a watch report.
WatchesPathReport	getWatchesByPath() Returns a watch report by path.
WatchesSummary	getWatchesSummary() Returns a watch summary.
DataTree.ProcessTxnResult	processTxn(TxnHeader header, Record txn)
DataTree.ProcessTxnResult	processTxn(TxnHeader header, Record txn, boolean isSubTxn)
DataTree.ProcessTxnResult	processTxn(TxnHeader header, Record txn, TxnDigest digest)
void	removeCnxn(Watcher watcher)
boolean	removeWatch(String path, Watcher.WatcherType type, Watcher watcher)
void	reportDigestMismatch(long zxid) Reports any mismatch in the transaction digest.
void	serialize(OutputArchive oa, String tag)
void	serializeAcls(OutputArchive oa)
void	serializeNodeData(OutputArchive oa, String path, DataNode node)
void	serializeNodes(OutputArchive oa)
boolean	serializeZxidDigest(OutputArchive oa) Serializing the digest to snapshot, this is done after the data tree is being serialized, so when we replay the txns and it hits this zxid we know we should be in a non-fuzzy state, and have the same digest.
Stat	setACL(String path, List<ACL> acl, int version)
void	setCversionPzxid(String path, int newCversion, long zxid) This method sets the Cversion and Pzxid for the specified node to the values passed as arguments.
Stat	setData(String path, byte[] data, int version, long zxid, long time)
void	setWatches(long relativeZxid, List<String> dataWatches, List<String> existWatches, List<String> childWatches, List<String> persistentWatches, List<String> persistentRecursiveWatches, Watcher watcher)
void	shutdownWatcher()
Stat	statNode(String path, Watcher watcher)
void	updateCountBytes(String lastPrefix, long bytesDiff, int countDiff) update the count/count of bytes of this stat datanode

Methods inherited from class java.lang.Object

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

Field Detail

STAT_OVERHEAD_BYTES

public static final int STAT_OVERHEAD_BYTES

over-the-wire size of znode's stat. Counting the fields of Stat class

See Also:

Constant Field Values

DIGEST_LOG_LIMIT

public static final int DIGEST_LOG_LIMIT

See Also:

Constant Field Values

DIGEST_LOG_INTERVAL

public static final int DIGEST_LOG_INTERVAL

See Also:

Constant Field Values

lastProcessedZxid

public volatile long lastProcessedZxid

Constructor Detail

DataTree

public DataTree()

Method Detail

getEphemerals

public Set<String> getEphemerals(long sessionId)

getContainers

public Set<String> getContainers()

getTtls

public Set<String> getTtls()

getSessions

public Collection<Long> getSessions()

getNode

public DataNode getNode(String path)

getNodeCount

public int getNodeCount()

getWatchCount

public int getWatchCount()

getEphemeralsCount

public int getEphemeralsCount()

approximateDataSize

public long approximateDataSize()

Get the size of the nodes based on path and data length.

Returns:

size of the data

cachedApproximateDataSize

public long cachedApproximateDataSize()

addConfigNode

public void addConfigNode()

create a /zookeeper/config node for maintaining the configuration (membership and quorum system) info for zookeeper

copyStatPersisted

public static void copyStatPersisted(StatPersisted from,
                                     StatPersisted to)

copyStat

public static void copyStat(Stat from,
                            Stat to)

updateCountBytes

public void updateCountBytes(String lastPrefix,
                             long bytesDiff,
                             int countDiff)

update the count/count of bytes of this stat datanode

Parameters:

lastPrefix - the path of the node that is quotaed.

bytesDiff - the diff to be added to number of bytes

countDiff - the diff to be added to the count

createNode

public void createNode(String path,
                       byte[] data,
                       List<ACL> acl,
                       long ephemeralOwner,
                       int parentCVersion,
                       long zxid,
                       long time)
                throws KeeperException.NoNodeException,
                       KeeperException.NodeExistsException

Add a new node to the DataTree.

Parameters:

path - Path for the new node.

data - Data to store in the node.

acl - Node acls

ephemeralOwner - the session id that owns this node. -1 indicates this is not an ephemeral node.

zxid - Transaction ID

time -

Throws:

KeeperException.NodeExistsException

KeeperException.NoNodeException

createNode

public void createNode(String path,
                       byte[] data,
                       List<ACL> acl,
                       long ephemeralOwner,
                       int parentCVersion,
                       long zxid,
                       long time,
                       Stat outputStat)
                throws KeeperException.NoNodeException,
                       KeeperException.NodeExistsException

Add a new node to the DataTree.

Parameters:

path - Path for the new node.

data - Data to store in the node.

acl - Node acls

ephemeralOwner - the session id that owns this node. -1 indicates this is not an ephemeral node.

zxid - Transaction ID

time -

outputStat - A Stat object to store Stat output results into.

Throws:

KeeperException.NodeExistsException

KeeperException.NoNodeException

deleteNode

public void deleteNode(String path,
                       long zxid)
                throws KeeperException.NoNodeException

remove the path from the datatree

Parameters:

path - the path to of the node to be deleted

zxid - the current zxid

Throws:

KeeperException.NoNodeException

setData

public Stat setData(String path,
                    byte[] data,
                    int version,
                    long zxid,
                    long time)
             throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

getMaxPrefixWithQuota

public String getMaxPrefixWithQuota(String path)

If there is a quota set, return the appropriate prefix for that quota Else return null

Parameters:

path - The ZK path to check for quota

Returns:

Max quota prefix, or null if none

addWatch

public void addWatch(String basePath,
                     Watcher watcher,
                     int mode)

getData

public byte[] getData(String path,
                      Stat stat,
                      Watcher watcher)
               throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

statNode

public Stat statNode(String path,
                     Watcher watcher)
              throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

getChildren

public List<String> getChildren(String path,
                                Stat stat,
                                Watcher watcher)
                         throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

getAllChildrenNumber

public int getAllChildrenNumber(String path)

setACL

public Stat setACL(String path,
                   List<ACL> acl,
                   int version)
            throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

getACL

public List<ACL> getACL(String path,
                        Stat stat)
                 throws KeeperException.NoNodeException

Throws:

KeeperException.NoNodeException

getACL

public List<ACL> getACL(DataNode node)

aclCacheSize

public int aclCacheSize()

processTxn

public DataTree.ProcessTxnResult processTxn(TxnHeader header,
                                            Record txn,
                                            TxnDigest digest)

processTxn

public DataTree.ProcessTxnResult processTxn(TxnHeader header,
                                            Record txn)

processTxn

public DataTree.ProcessTxnResult processTxn(TxnHeader header,
                                            Record txn,
                                            boolean isSubTxn)

serializeNodeData

public void serializeNodeData(OutputArchive oa,
                              String path,
                              DataNode node)
                       throws IOException

Throws:

IOException

serializeAcls

public void serializeAcls(OutputArchive oa)
                   throws IOException

Throws:

IOException

serializeNodes

public void serializeNodes(OutputArchive oa)
                    throws IOException

Throws:

IOException

serialize

public void serialize(OutputArchive oa,
                      String tag)
               throws IOException

Throws:

IOException

deserialize

public void deserialize(InputArchive ia,
                        String tag)
                 throws IOException

Throws:

IOException

dumpWatchesSummary

public void dumpWatchesSummary(PrintWriter pwriter)

Summary of the watches on the datatree.

Parameters:

pwriter - the output to write to

dumpWatches

public void dumpWatches(PrintWriter pwriter,
                        boolean byPath)

Write a text dump of all the watches on the datatree. Warning, this is expensive, use sparingly!

Parameters:

pwriter - the output to write to

getWatches

public WatchesReport getWatches()

Returns a watch report.

Returns:

watch report

See Also:

WatchesReport

getWatchesByPath

public WatchesPathReport getWatchesByPath()

Returns a watch report by path.

Returns:

watch report

See Also:

WatchesPathReport

getWatchesSummary

public WatchesSummary getWatchesSummary()

Returns a watch summary.

Returns:

watch summary

See Also:

WatchesSummary

dumpEphemerals

public void dumpEphemerals(PrintWriter pwriter)

Write a text dump of all the ephemerals in the datatree.

Parameters:

pwriter - the output to write to

shutdownWatcher

public void shutdownWatcher()

getEphemerals

public Map<Long,Set<String>> getEphemerals()

Returns a mapping of session ID to ephemeral znodes.

Returns:

map of session ID to sets of ephemeral znodes

removeCnxn

public void removeCnxn(Watcher watcher)

setWatches

public void setWatches(long relativeZxid,
                       List<String> dataWatches,
                       List<String> existWatches,
                       List<String> childWatches,
                       List<String> persistentWatches,
                       List<String> persistentRecursiveWatches,
                       Watcher watcher)

setCversionPzxid

public void setCversionPzxid(String path,
                             int newCversion,
                             long zxid)
                      throws KeeperException.NoNodeException

This method sets the Cversion and Pzxid for the specified node to the values passed as arguments. The values are modified only if newCversion is greater than the current Cversion. A NoNodeException is thrown if a znode for the specified path is not found.

Parameters:

path - Full path to the znode whose Cversion needs to be modified. A "/" at the end of the path is ignored.

newCversion - Value to be assigned to Cversion

zxid - Value to be assigned to Pzxid

Throws:

KeeperException.NoNodeException - If znode not found.

containsWatcher

public boolean containsWatcher(String path,
                               Watcher.WatcherType type,
                               Watcher watcher)

removeWatch

public boolean removeWatch(String path,
                           Watcher.WatcherType type,
                           Watcher watcher)

getReferenceCountedAclCache

public ReferenceCountedACLCache getReferenceCountedAclCache()

serializeZxidDigest

public boolean serializeZxidDigest(OutputArchive oa)
                            throws IOException

Serializing the digest to snapshot, this is done after the data tree is being serialized, so when we replay the txns and it hits this zxid we know we should be in a non-fuzzy state, and have the same digest.

Parameters:

oa - the output stream to write to

Returns:

true if the digest is serialized successfully

Throws:

IOException

deserializeZxidDigest

public boolean deserializeZxidDigest(InputArchive ia,
                                     long startZxidOfSnapshot)
                              throws IOException

Deserializing the zxid digest from the input stream and update the digestFromLoadedSnapshot.

Parameters:

ia - the input stream to read from

startZxidOfSnapshot - the zxid of snapshot file

Returns:

the true if it deserialized successfully

Throws:

IOException

compareSnapshotDigests

public void compareSnapshotDigests(long zxid)

Compares the actual tree's digest with that in the snapshot. Resets digestFromLoadedSnapshot after comparision.

Parameters:

zxid - zxid

compareDigest

public boolean compareDigest(TxnHeader header,
                             Record txn,
                             TxnDigest digest)

Compares the digest of the tree with the digest present in transaction digest. If there is any error, logs and alerts the watchers.

Parameters:

header - transaction header being applied

txn - transaction

digest - transaction digest

Returns:

false if digest in the txn doesn't match what we have now in the data tree

reportDigestMismatch

public void reportDigestMismatch(long zxid)

Reports any mismatch in the transaction digest.

Parameters:

zxid - zxid for which the error is being reported.

getTreeDigest

public long getTreeDigest()

getLastProcessedZxidDigest

public DataTree.ZxidDigest getLastProcessedZxidDigest()

getDigestFromLoadedSnapshot

public DataTree.ZxidDigest getDigestFromLoadedSnapshot()

addDigestWatcher

public void addDigestWatcher(DigestWatcher digestWatcher)

Add digest mismatch event handler.

Parameters:

digestWatcher - the handler to add

getDigestLog

public List<DataTree.ZxidDigest> getDigestLog()

Return all the digests in the historical digest list.

createStat

public static StatPersisted createStat(long zxid,
                                       long time,
                                       long ephemeralOwner)

Create a node stat from the given params.

Parameters:

zxid - the zxid associated with the txn

time - the time when the txn is created

ephemeralOwner - the owner if the node is an ephemeral

Returns:

the stat