alluxio

Class AbstractClient

java.lang.Object

alluxio.AbstractClient

All Implemented Interfaces:

Client, Closeable, AutoCloseable

Direct Known Subclasses:

AbstractMasterClient

@ThreadSafe
public abstract class AbstractClient
extends Object
implements Client

AbstractClient is the base class for all the grpc clients in alluxio. It provides framework methods for the grpc workflow like connection, version checking and automatic retrying for rpc calls.

Concrete Child classes extend this class by filling in the missing component, like where to find the actual server address queryGrpcServerAddress(), and rpc callables to retryRPC(RpcCallable, Logger, String, String, Object...) that carries actual logic.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static interface	AbstractClient.RpcCallable<V> The RPC to be executed in retryRPC(alluxio.AbstractClient.RpcCallable<V>, org.slf4j.Logger, java.lang.String, java.lang.String, java.lang.Object...).

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	mAlwaysEnableTLS
protected GrpcChannel	mChannel Underlying channel to the target service.
protected boolean	mClosed Is true if this client was closed by the user.
protected boolean	mConnected Is true if this client is currently connected.
protected ClientContext	mContext Context of the client.
protected GrpcServerAddress	mServerAddress Grpc Address of the remote server.
protected long	mServiceVersion Stores the actual remote service version, used to compare with expected local version.
protected ServiceVersionClientServiceGrpc.ServiceVersionClientServiceBlockingStub	mVersionService

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractClient(ClientContext context) Creates a new client base with default retry policy supplier.
protected	AbstractClient(ClientContext context, boolean alwaysEnableTLS)
protected	AbstractClient(ClientContext context, java.util.function.Supplier<RetryPolicy> retryPolicySupplier) Creates a new client base with specified retry policy supplier.

Method Summary

Modifier and Type	Method and Description
protected void	afterConnect() This method is called after the connection is made to the remote.
protected void	afterDisconnect() This method is called after the connection is disconnected.
protected void	beforeConnect() This method is called before the connection is connected.
protected void	beforeDisconnect() This method is called before the connection is disconnected.
protected void	checkVersion(long clientVersion) Checks that the service version is compatible with the client.
void	close() Closes the connection with the remote permanently.
void	connect() Connects with the remote.
void	connectWithRuntimeException() Connects with the remote server.
protected GrpcChannel	createChannel()
void	disconnect() Closes the connection with the Alluxio remote and does the necessary cleanup.
InetSocketAddress	getConfAddress() By default, return the same underlying address as getRemoteSockAddress().
String	getRemoteHostName()
protected abstract ServiceType	getRemoteServiceType()
protected long	getRemoteServiceVersion()
SocketAddress	getRemoteSockAddress()
protected abstract String	getServiceName()
protected abstract long	getServiceVersion()
boolean	isClosed()
boolean	isConnected() Returns the connected status of the client.
protected abstract GrpcServerAddress	queryGrpcServerAddress() AbstractClient works with Grpc Servers.
protected <V> V	retryRPC(AbstractClient.RpcCallable<V> rpc, org.slf4j.Logger logger, String rpcName, String description, Object... args) Tries to execute an RPC defined as a AbstractClient.RpcCallable.
protected <V> V	retryRPC(RetryPolicy retryPolicy, AbstractClient.RpcCallable<V> rpc, org.slf4j.Logger logger, String rpcName, String description, Object... args)

Methods inherited from class java.lang.Object

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

Field Detail

mServerAddress

protected GrpcServerAddress mServerAddress

Grpc Address of the remote server. This field is lazily initialized by queryGrpcServerAddress(), and could only be null right after instantiation and before use.

mChannel

protected GrpcChannel mChannel

Underlying channel to the target service.

mVersionService

protected ServiceVersionClientServiceGrpc.ServiceVersionClientServiceBlockingStub mVersionService

mAlwaysEnableTLS

protected boolean mAlwaysEnableTLS

mConnected

protected boolean mConnected

Is true if this client is currently connected.

mClosed

protected volatile boolean mClosed

Is true if this client was closed by the user. No further actions are possible after the client is closed.

mServiceVersion

protected long mServiceVersion

Stores the actual remote service version, used to compare with expected local version.

mContext

protected ClientContext mContext

Context of the client.

Constructor Detail

AbstractClient

protected AbstractClient(ClientContext context)

Creates a new client base with default retry policy supplier.

Parameters:

context - information required to connect to Alluxio

AbstractClient

protected AbstractClient(ClientContext context,
                         boolean alwaysEnableTLS)

AbstractClient

protected AbstractClient(ClientContext context,
                         java.util.function.Supplier<RetryPolicy> retryPolicySupplier)

Creates a new client base with specified retry policy supplier.

Parameters:

context - information required to connect to Alluxio

retryPolicySupplier - factory for retry policies to be used when performing RPCs

Method Detail

getRemoteServiceType

protected abstract ServiceType getRemoteServiceType()

Returns:

the expected type of remote service

getRemoteServiceVersion

protected long getRemoteServiceVersion()
                                throws AlluxioStatusException

Returns:

the actual remote service version

Throws:

AlluxioStatusException - if query rpc failed

getServiceName

protected abstract String getServiceName()

Returns:

a string representing the specific service

getServiceVersion

protected abstract long getServiceVersion()

Returns:

the client service version

checkVersion

protected void checkVersion(long clientVersion)
                     throws IOException

Checks that the service version is compatible with the client.

Parameters:

clientVersion - the client version

Throws:

IOException

afterConnect

protected void afterConnect()
                     throws IOException

This method is called after the connection is made to the remote. Implementations should create internal state to finish the connection process.

Throws:

IOException

beforeConnect

protected void beforeConnect()
                      throws IOException

This method is called before the connection is connected. Implementations should add any additional operations before the connection is connected. loading the cluster defaults

Throws:

IOException

afterDisconnect

protected void afterDisconnect()

This method is called after the connection is disconnected. Implementations should clean up any additional state created for the connection.

beforeDisconnect

protected void beforeDisconnect()

This method is called before the connection is disconnected. Implementations should add any additional operations before the connection is disconnected.

connectWithRuntimeException

public void connectWithRuntimeException()

Connects with the remote server.

Throws:

AlluxioRuntimeException - network connection error

createChannel

protected GrpcChannel createChannel()
                             throws AlluxioStatusException

Throws:

AlluxioStatusException

connect

public void connect()
             throws AlluxioStatusException

Connects with the remote.

Specified by:

connect in interface Client

Throws:

AlluxioStatusException

disconnect

public void disconnect()

Description copied from interface: Client

Closes the connection with the Alluxio remote and does the necessary cleanup. It should be used if the client has not connected with the remote for a while, for example.

Specified by:

disconnect in interface Client

isConnected

public boolean isConnected()

Description copied from interface: Client

Returns the connected status of the client.

Specified by:

isConnected in interface Client

Returns:

true if this client is connected to the remote

close

public void close()

Closes the connection with the remote permanently. This instance should be not be reused after closing.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

queryGrpcServerAddress

protected abstract GrpcServerAddress queryGrpcServerAddress()
                                                     throws UnavailableException

AbstractClient works with Grpc Servers. Child classes should only override this method to query the address of the grpc server they talk to. The conversion from GrpcServerAddress to more generic SocketAddress required by Client.getRemoteSockAddress() is handled by this class.

Returns:

the GrpcServerAddress of the remote server

Throws:

UnavailableException - if address can't be determined

getRemoteSockAddress

public SocketAddress getRemoteSockAddress()
                                   throws UnavailableException

Specified by:

getRemoteSockAddress in interface Client

Returns:

the SocketAddress of the remote

Throws:

UnavailableException - if the primary address cannot be determined

getRemoteHostName

public String getRemoteHostName()
                         throws UnavailableException

Specified by:

getRemoteHostName in interface Client

Returns:

the host name of the remote

Throws:

UnavailableException - if the primary address cannot be determined

getConfAddress

public InetSocketAddress getConfAddress()
                                 throws UnavailableException

By default, return the same underlying address as getRemoteSockAddress(). Child classes should override this implementation if they intend to have different address to fetch configuration.

Specified by:

getConfAddress in interface Client

Returns:

the remote address of the configuration server

Throws:

UnavailableException - if address cannot be determined

retryRPC

protected <V> V retryRPC(AbstractClient.RpcCallable<V> rpc,
                         org.slf4j.Logger logger,
                         String rpcName,
                         String description,
                         Object... args)
                  throws AlluxioStatusException

Tries to execute an RPC defined as a AbstractClient.RpcCallable. Metrics will be recorded based on the provided rpc name. If a UnavailableException occurs, a reconnection will be tried through connect() and the action will be re-executed.

Type Parameters:

V - type of return value of the RPC call

Parameters:

rpc - the RPC call to be executed

logger - the logger to use for this call

rpcName - the human-readable name of the RPC call

description - the format string of the description, used for logging

args - the arguments for the description

Returns:

the return value of the RPC call

Throws:

AlluxioStatusException - status exception

retryRPC

protected <V> V retryRPC(RetryPolicy retryPolicy,
                         AbstractClient.RpcCallable<V> rpc,
                         org.slf4j.Logger logger,
                         String rpcName,
                         String description,
                         Object... args)
                  throws AlluxioStatusException

Throws:

AlluxioStatusException

isClosed

public boolean isClosed()

Specified by:

isClosed in interface Client

Returns:

whether the client is closed