alluxio.client.file

Class FileSystemContextReinitializer

java.lang.Object

alluxio.client.file.FileSystemContextReinitializer

All Implemented Interfaces:

Closeable, AutoCloseable

public final class FileSystemContextReinitializer
extends Object
implements Closeable

Reinitializes FileSystemContext inside BaseFileSystem. A daemon heartbeat thread periodically fetches configuration hashes from meta master, if they differ from the hashes in the ClientContext backing the FileSystemContext, it tries to reinitialize the FileSystemContext. Each RPC needs to call block() to mark its lifetime, when there are ongoing RPCs executing between these two methods, reinitialization is blocked. Reinitialization starts when there are no ongoing RPCs, after starting, all further RPCs are blocked until the reinitialization finishes or until timeout. If it succeeds, future RPCs will use the reinitialized context, otherwise, an exception is thrown from block().

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FileSystemContextReinitializer.ReinitAllowerResource This resource allows reinitialization.
static class	FileSystemContextReinitializer.ReinitBlockerResource This resource blocks reinitialization until close.

Constructor Summary

Constructors

Constructor and Description
FileSystemContextReinitializer(FileSystemContext context) Creates a new reinitializer for the context.

Method Summary

Modifier and Type	Method and Description
FileSystemContextReinitializer.ReinitAllowerResource	allow() Acquires the resource to allow reinitialization.
FileSystemContextReinitializer.ReinitBlockerResource	block() Acquires the resource to block reinitialization.
void	close() Shuts down the heartbeat thread immediately.
void	onSuccess() Notifies that the reinitialization has succeeded.

Methods inherited from class java.lang.Object

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

Constructor Detail

FileSystemContextReinitializer

public FileSystemContextReinitializer(FileSystemContext context)

Creates a new reinitializer for the context. The heartbeat will be started.

Parameters:

context - the context to be reinitialized

Method Detail

onSuccess

public void onSuccess()

Notifies that the reinitialization has succeeded. It will reset internal state that might be affected by the reinitialized context, e.g. the meta master client used in the heartbeat might need to be reset because of new configurations.

block

public FileSystemContextReinitializer.ReinitBlockerResource block()
                                                           throws IOException,
                                                                  InterruptedException

Acquires the resource to block reinitialization. When the context is being reinitialized, this call blocks. If the reinitialization fails, an exception is thrown. If there is an existing reinitialization exception, immediately throw an exception without trying to block further reinitialization.

Returns:

the resource

Throws:

IOException - when reinitialization fails before or during this method

InterruptedException - if interrupted during being blocked

allow

public FileSystemContextReinitializer.ReinitAllowerResource allow()

Acquires the resource to allow reinitialization. This call blocks until there are no ongoing operations holding the resource returned by block(). When it returns, further calls to block() block until the returned resource is closed.

Returns:

the resource

close

public void close()

Shuts down the heartbeat thread immediately. If already closed, this is a noop.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable