alluxio.membership

Class AlluxioEtcdClient

java.lang.Object

alluxio.membership.AlluxioEtcdClient

public class AlluxioEtcdClient
extends Object

Wrapper class around jetcd client to achieve utilities API to talk with ETCD. This class is supposed to be used as a singleton fashion. It wraps around one jetcd Client instance for all sorts of utility functions to interact with etcd. Only state it's keeping is the jetcd Client and registered Watcher list For kv operations such as Put(createForPath, deleteForPath, addChildren, etc.) its atomicity/consistency semantics goes with what ETCD has to offer, this class does not add upon any semantics itself. AlluxioEtcdClient should only be used as singleton wrapping one jetcd Client object, currently only resource - jetcd client will be closed as part of close() which is called during: 1) Worker shutdown or close as part of EtcdMembershipManager close 2) FileSystemContext closeContext as part of EtcdMembershipManager close As we never set mClient to be null after connect, also jetcd client can be closed idempotently so it's ok to ignore thread safety for close() As for jetcd Client, it's managing its own connect/reconnect/loadbalance to other etcd instances, will leave these logic to jetcd client itself for now unless we need to handle it in our layer.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static interface	AlluxioEtcdClient.EtcdUtilCallable<V>
static class	AlluxioEtcdClient.Lease Lease structure to keep the info about a lease in etcd.

Field Summary

Fields

Modifier and Type	Field and Description
static String	BASE_PATH
static long	DEFAULT_LEASE_TTL_IN_SEC
static long	DEFAULT_TIMEOUT_IN_SEC
ServiceDiscoveryRecipe	mServiceDiscovery
static int	RETRY_TIMES

Constructor Summary

Constructors

Constructor and Description
AlluxioEtcdClient(AlluxioConfiguration conf) CTOR for AlluxioEtcdClient.

Method Summary

Modifier and Type	Method and Description
void	addChildren(String parentPath, String childPath, byte[] value) Create a childPath with value to a parentPath.
void	addChildrenListener(String parentPath, StateListener listener) Add state listener to watch children for given path.
void	addStateListener(String path, StateListener listener) Add state listener to given path.
boolean	checkExistsForPath(String path) Check existence of a single given path.
void	createForPath(String path, Optional<byte[]> value) Create a path with given value in non-transactional way.
AlluxioEtcdClient.Lease	createLease() Create lease with default ttl and timeout.
AlluxioEtcdClient.Lease	createLease(long ttlInSec, long timeout, TimeUnit timeUnit) Create a lease with timeout and ttl.
void	deleteForPath(String path, boolean recursive) Delete a path or recursively all paths with given path as prefix.
static void	destroy() Destroys the client and corresponding resources.
List<io.etcd.jetcd.KeyValue>	getChildren(String parentPath) Get list of children path kv pairs from a given parentPath e.g.
io.etcd.jetcd.Client	getEtcdClient() Get the jetcd client instance.
byte[]	getForPath(String path) Get latest value attached to the path.
static AlluxioEtcdClient	getInstance(AlluxioConfiguration conf) Get the singleton instance of AlluxioEtcdClient.
boolean	isLeaseExpired(AlluxioEtcdClient.Lease lease) Check with etcd if a lease is already expired.
void	removeChildrenListener(String parentPath) Remove state listener for children on a given parentPath.
void	removeListenerInternal(String path, alluxio.membership.AlluxioEtcdClient.WatchType watchType) Remove listener on given path.
void	removeStateListener(String path) Remove state listener for give path.
void	revokeLease(AlluxioEtcdClient.Lease lease) Revoke given lease.

Methods inherited from class java.lang.Object

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

Field Detail

BASE_PATH

public static final String BASE_PATH

See Also:

Constant Field Values

DEFAULT_LEASE_TTL_IN_SEC

public static final long DEFAULT_LEASE_TTL_IN_SEC

See Also:

Constant Field Values

DEFAULT_TIMEOUT_IN_SEC

public static final long DEFAULT_TIMEOUT_IN_SEC

See Also:

Constant Field Values

RETRY_TIMES

public static final int RETRY_TIMES

See Also:

Constant Field Values

mServiceDiscovery

public final ServiceDiscoveryRecipe mServiceDiscovery

Constructor Detail

AlluxioEtcdClient

public AlluxioEtcdClient(AlluxioConfiguration conf)

CTOR for AlluxioEtcdClient.

Parameters:

conf -

Method Detail

getInstance

public static AlluxioEtcdClient getInstance(AlluxioConfiguration conf)

Get the singleton instance of AlluxioEtcdClient.

Parameters:

conf -

Returns:

AlluxioEtcdClient

createLease

public AlluxioEtcdClient.Lease createLease(long ttlInSec,
                                           long timeout,
                                           TimeUnit timeUnit)

Create a lease with timeout and ttl.

Parameters:

ttlInSec -

timeout -

timeUnit -

Returns:

Lease

createLease

public AlluxioEtcdClient.Lease createLease()

Create lease with default ttl and timeout.

Returns:

Lease

revokeLease

public void revokeLease(AlluxioEtcdClient.Lease lease)

Revoke given lease.

Parameters:

lease -

isLeaseExpired

public boolean isLeaseExpired(AlluxioEtcdClient.Lease lease)

Check with etcd if a lease is already expired.

Parameters:

lease -

Returns:

lease expired

addChildren

public void addChildren(String parentPath,
                        String childPath,
                        byte[] value)

Create a childPath with value to a parentPath. e.g. create "lower_path" under path /upper_path/ to form a kv pair of /upper_path/lower_path with a given value.

Parameters:

parentPath -

childPath -

value -

getChildren

public List<io.etcd.jetcd.KeyValue> getChildren(String parentPath)

Get list of children path kv pairs from a given parentPath e.g. get [/upper/lower1 - val1, /upper/lower2 - val2] under parent path /upper/

Parameters:

parentPath - parentPath ends with /

Returns:

list of children KeyValues

addStateListener

public void addStateListener(String path,
                             StateListener listener)

Add state listener to given path.

Parameters:

path -

listener -

removeStateListener

public void removeStateListener(String path)

Remove state listener for give path.

Parameters:

path -

addChildrenListener

public void addChildrenListener(String parentPath,
                                StateListener listener)

Add state listener to watch children for given path.

Parameters:

parentPath -

listener -

removeChildrenListener

public void removeChildrenListener(String parentPath)

Remove state listener for children on a given parentPath.

Parameters:

parentPath -

getForPath

public byte[] getForPath(String path)

Get latest value attached to the path.

Parameters:

path -

Returns:

byte[] value

checkExistsForPath

public boolean checkExistsForPath(String path)

Check existence of a single given path.

Parameters:

path -

Returns:

if the path exists or not

createForPath

public void createForPath(String path,
                          Optional<byte[]> value)

Create a path with given value in non-transactional way.

Parameters:

path -

value -

deleteForPath

public void deleteForPath(String path,
                          boolean recursive)

Delete a path or recursively all paths with given path as prefix.

Parameters:

path -

recursive -

removeListenerInternal

public void removeListenerInternal(String path,
                                   alluxio.membership.AlluxioEtcdClient.WatchType watchType)

Remove listener on given path.

Parameters:

path -

watchType -

getEtcdClient

public io.etcd.jetcd.Client getEtcdClient()

Get the jetcd client instance.

Returns:

jetcd client

destroy

public static void destroy()

Destroys the client and corresponding resources. We don't implement AutoCloseable because the client is used by client FileSystemContext. FileSystemContext has reinit() logic which may close and recreate all resources. We don't want the life cycle of one FileSystemContext to close the global singleton ETCD client.