com.bigdata.ha

Interface HAPipelineGlue

All Superinterfaces:

Remote

All Known Subinterfaces:

HAGlue

All Known Implementing Classes:

AbstractJournal.BasicHA

public interface HAPipelineGlue
extends Remote

A Remote interface supporting the write replication pipeline. The quorum leader accepts writes from the application layer. The writes are formatted onto low-level cache blocks. Those cache blocks are replicated from the quorum leader to the quorum followers along the pipeline.

Version:

$Id$

Author:

Bryan Thompson

See Also:

QuorumPipeline

Method Summary

Methods

Modifier and Type	Method and Description
IHALogRootBlocksResponse	getHALogRootBlocksForWriteSet(IHALogRootBlocksRequest msg) Request the root blocks for the HA Log for the specified commit point.
IHAWriteSetStateResponse	getHAWriteSetState(IHAWriteSetStateRequest req) Request metadata about the current write set from the quorum leader.
InetSocketAddress	getWritePipelineAddr() Return the address at which this service will listen for write pipeline messages sent from the upstream service.
Future<Void>	moveToEndOfPipeline() Instruct the service to move to the end of the write pipeline.
Future<Void>	receiveAndReplicate(IHASyncRequest req, IHASendState snd, IHAWriteMessage msg) Accept metadata describing an NIO buffer transfer along the write pipeline.
Future<IHAPipelineResetResponse>	resetPipeline(IHAPipelineResetRequest req) Reset the pipeline (blocking).
Future<Void>	sendHALogForWriteSet(IHALogRequest msg) The recipient will send the WriteCache blocks for the specified write set on the write pipeline.
Future<IHASendStoreResponse>	sendHAStore(IHARebuildRequest msg) Send the raw blocks for the requested backing store across the write pipeline.

Method Detail

getWritePipelineAddr

InetSocketAddress getWritePipelineAddr()
                                       throws IOException

Return the address at which this service will listen for write pipeline messages sent from the upstream service.

Throws:

IOException

moveToEndOfPipeline

Future<Void> moveToEndOfPipeline()
                                 throws IOException

Instruct the service to move to the end of the write pipeline. The leader MUST be the first service in the write pipeline since it is the service to which the application directs all write requests. This message is used when a leader will be elected and it needs to force other services before it in the write pipeline to leave/add themselves from/to the write pipeline such that the leader becomes the first service in the write pipeline.

Throws:

IOException

resetPipeline

Future<IHAPipelineResetResponse> resetPipeline(IHAPipelineResetRequest req)
                                               throws IOException

Reset the pipeline (blocking). This message is used to handle an error in pipeline replication. If replication fails, the socket connections both upstream and downstream of the point of failure can be left in an indeterminate state with partially buffered data. In order to bring the pipeline back into a known state (without forcing a quorum break) we message each service in the pipeline to reset its HAReceiveService (including the inner HASendService). The next message and payload relayed from the leader will cause new socket connections to be established.

Parameters:

msg - The request.

Returns:

The Future for the operation on the remote service.

Throws:

IOException

receiveAndReplicate

Future<Void> receiveAndReplicate(IHASyncRequest req,
                               IHASendState snd,
                               IHAWriteMessage msg)
                                 throws IOException

Accept metadata describing an NIO buffer transfer along the write pipeline. This method is never invoked on the master. It is only invoked on the failover nodes, including the last node in the failover chain.

Parameters:

req - A request for an HALog (optional). This is only non-null when historical WriteCache blocks are being replayed down the write pipeline in order to synchronize a service.

snd - Metadata about the state of the sender and potentially the routing of the payload along the write replication pipeline.

msg - The metadata.

Returns:

The Future which will become available once the buffer transfer is complete.

Throws:

IOException

getHAWriteSetState

IHAWriteSetStateResponse getHAWriteSetState(IHAWriteSetStateRequest req)
                                            throws IOException

Request metadata about the current write set from the quorum leader.

Parameters:

req - The request.

Returns:

The response.

Throws:

IOException

getHALogRootBlocksForWriteSet

IHALogRootBlocksResponse getHALogRootBlocksForWriteSet(IHALogRootBlocksRequest msg)
                                                       throws IOException

Request the root blocks for the HA Log for the specified commit point.

Parameters:

msg - The request (specifies the desired HA Log by the commit counter of the closing root block).

Returns:

The requested root blocks.

Throws:

IOException

sendHALogForWriteSet

Future<Void> sendHALogForWriteSet(IHALogRequest msg)
                                  throws IOException

The recipient will send the WriteCache blocks for the specified write set on the write pipeline. These WriteCache blocks will be visible to ALL services in the write pipeline. It is important that all services ignore WriteCache blocks that are not in sequence for the current write set unless they have explicitly requested an HALog using this method.

Note: The WriteCache blocks are sent on the write pipeline. Therefore, a service MUST NOT request the write set from a service that is downstream from it in the write pipeline. It is always safe to request the data from the leader.

Note: The HAWriteMessage includes a quorum token. When historical WriteCache blocks are being replicated in response to this method, the will be replicated using the quorum token that was in effect for that write set. Implementations MUST NOT perform asserts on the quorum token until after they have determined that the message is for the current write set.

Note: DO NOT use a ThickFuture for the returned Future. That will defeat the ability of the requester to cancel the Future.

Parameters:

req - A request for an HALog.

Returns:

A Future that may be used to cancel the remote process sending the data through the write pipeline.

Throws:

IOException

sendHAStore

Future<IHASendStoreResponse> sendHAStore(IHARebuildRequest msg)
                                         throws IOException

Send the raw blocks for the requested backing store across the write pipeline.

Note: This method supports disaster recovery of a service from a met quorum. This procedure can only be used when a met quorum exists.

Note: DO NOT use a ThickFuture for the returned Future. That will defeat the ability of the requester to cancel the Future.

Parameters:

req - A request to replicate a backing store.

Returns:

A Future that may be used to cancel the remote process sending the data through the write pipeline. The Future will report the current root block in effect as of the moment when the sendHAStore operation was completed.

Throws:

IOException