org.apache.oozie.service

Class ZKLocksService

java.lang.Object

org.apache.oozie.service.MemoryLocksService

org.apache.oozie.service.ZKLocksService

All Implemented Interfaces:

Service, Instrumentable

public class ZKLocksService
extends MemoryLocksService
implements Service, Instrumentable

Service that provides distributed locks via ZooKeeper. Requires that a ZooKeeper ensemble is available. The locks will be located under a ZNode named "locks" under the namespace (see ZKUtils). For example, with default settings, if the resource we're locking is called "foo", then the ZNode backing the lock will be at /oozie/locks/foo.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_REAPING_THRESHOLD
static String	LOCKS_NODE
static String	REAPING_THREADS
static String	REAPING_THRESHOLD

Fields inherited from class org.apache.oozie.service.MemoryLocksService

INSTRUMENTATION_GROUP

Fields inherited from interface org.apache.oozie.service.Service

CONF_PREFIX, DEFAULT_LOCK_TIMEOUT, lockTimeout, USE_XCOMMAND

Constructor Summary

Constructors

Constructor and Description
ZKLocksService()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() Destroy the zookeeper locks service.
HashMap<String,org.apache.curator.framework.recipes.locks.InterProcessReadWriteLock>	getLocks()
LockToken	getReadLock(String resource, long wait) Obtain a READ lock for a source.
LockToken	getWriteLock(String resource, long wait) Obtain a WRITE lock for a source.
void	init(Services services) Initialize the zookeeper locks service
void	instrument(Instrumentation instr) Instruments the zookeeper locks service.

Methods inherited from class org.apache.oozie.service.MemoryLocksService

getInterface

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.oozie.service.Service

getInterface

Field Detail

LOCKS_NODE

public static final String LOCKS_NODE

See Also:

Constant Field Values

DEFAULT_REAPING_THRESHOLD

public static final int DEFAULT_REAPING_THRESHOLD

See Also:

Constant Field Values

REAPING_THRESHOLD

public static final String REAPING_THRESHOLD

See Also:

Constant Field Values

REAPING_THREADS

public static final String REAPING_THREADS

See Also:

Constant Field Values

Constructor Detail

ZKLocksService

public ZKLocksService()

Method Detail

init

public void init(Services services)
          throws ServiceException

Initialize the zookeeper locks service

Specified by:

init in interface Service

Overrides:

init in class MemoryLocksService

Parameters:

services - services instance.

Throws:

ServiceException - thrown if the service could not initialize.

destroy

public void destroy()

Destroy the zookeeper locks service.

Specified by:

destroy in interface Service

Overrides:

destroy in class MemoryLocksService

instrument

public void instrument(Instrumentation instr)

Instruments the zookeeper locks service.

Specified by:

instrument in interface Instrumentable

Overrides:

instrument in class MemoryLocksService

Parameters:

instr - instance to instrument the memory locks service to.

getReadLock

public LockToken getReadLock(String resource,
                    long wait)
                      throws InterruptedException

Obtain a READ lock for a source.

Overrides:

getReadLock in class MemoryLocksService

Parameters:

resource - resource name.

wait - time out in milliseconds to wait for the lock, -1 means no timeout and 0 no wait.

Returns:

the lock token for the resource, or null if the lock could not be obtained.

Throws:

InterruptedException - thrown if the thread was interrupted while waiting.

getWriteLock

public LockToken getWriteLock(String resource,
                     long wait)
                       throws InterruptedException

Obtain a WRITE lock for a source.

Overrides:

getWriteLock in class MemoryLocksService

Parameters:

resource - resource name.

wait - time out in milliseconds to wait for the lock, -1 means no timeout and 0 no wait.

Returns:

the lock token for the resource, or null if the lock could not be obtained.

Throws:

InterruptedException - thrown if the thread was interrupted while waiting.

getLocks

public HashMap<String,org.apache.curator.framework.recipes.locks.InterProcessReadWriteLock> getLocks()