com.bigdata.journal

Interface IHABufferStrategy

All Superinterfaces:

IAddressManager, IBufferStrategy, ICounterSetAccess, IMRMW, IMROW, IRawStore, IStreamStore

All Known Implementing Classes:

RWStrategy, WORMStrategy

public interface IHABufferStrategy
extends IBufferStrategy

A highly available IBufferStrategy.

Author:

Bryan Thompson

Field Summary

Fields inherited from interface com.bigdata.rawstore.IAddressManager

NULL

Method Summary

Methods

Modifier and Type	Method and Description
void	computeDigest(Object snapshot, MessageDigest digest) Compute the digest of the entire backing store (including the magic, file version, root blocks, etc).
long	getBlockSequence() Return the #of WriteCache blocks that were written out for the last write set.
long	getCurrentBlockSequence() Return the then-current write cache block sequence.
StoreState	getStoreState() A StoreState object references critical transient data that can be used to determine a degree of consistency between stores, specifically for an HA context.
WriteCacheService	getWriteCacheService() Return the WriteCacheService (mainly for debugging).
void	postHACommit(IRootBlockView rootBlock) Provides a trigger for synchronization of transient state after a commit.
ByteBuffer	readFromLocalStore(long addr) Read from the local store in support of failover reads on nodes in a highly available Quorum.
ByteBuffer	readRaw(long fileOffset, ByteBuffer transfer) Used to support the rebuild protocol.
void	resetFromHARootBlock(IRootBlockView rootBlock) Reload from the current root block - CAUTION : THIS IS NOT A RESET / ABORT.
Future<Void>	sendHALogBuffer(IHALogRequest req, IHAWriteMessage msg, IBufferAccess b) Send an IHAWriteMessage and the associated raw buffer through the write pipeline.
Future<Void>	sendRawBuffer(IHARebuildRequest req, long sequence, long quorumToken, long fileExtent, long offset, int nbytes, ByteBuffer b) Send an IHAWriteMessage and the associated raw buffer through the write pipeline.
void	setExtentForLocalStore(long extent) Extend local store for a highly available Quorum.
Object	snapshotAllocators() Snapshot the allocators in preparation for computing a digest of the committed allocations.
void	writeOnStream(OutputStream os, AbstractJournal.ISnapshotData coreData, Quorum<HAGlue,QuorumService<HAGlue>> quorum, long token) Write a consistent snapshot of the committed state of the backing store.
void	writeRawBuffer(HARebuildRequest req, IHAWriteMessage msg, ByteBuffer transfer) Used to support the rebuild protocol
void	writeRawBuffer(IHAWriteMessage msg, IBufferAccess b) Write a buffer containing data replicated from the master onto the local persistence store.

Methods inherited from interface com.bigdata.journal.IBufferStrategy

abort, closeForWrites, commit, getAddressManager, getBufferMode, getCounters, getExtent, getHeaderSize, getInitialExtent, getMaximumExtent, getMaxRecordSize, getMetaBitsAddr, getMetaStartAddr, getNextOffset, getOffsetBits, getUserExtent, isDirty, readRootBlock, requiresCommit, transferTo, truncate, useChecksums, writeRootBlock

Methods inherited from interface com.bigdata.rawstore.IRawStore

close, delete, deleteResources, destroy, force, getFile, getResourceMetadata, getUUID, isFullyBuffered, isOpen, isReadOnly, isStable, read, size, write

Methods inherited from interface com.bigdata.rawstore.IAddressManager

getByteCount, getOffset, getPhysicalAddress, toAddr, toString

Methods inherited from interface com.bigdata.rawstore.IStreamStore

getInputStream, getOutputStream

Method Detail

writeRawBuffer

void writeRawBuffer(IHAWriteMessage msg,
                  IBufferAccess b)
                    throws IOException,
                           InterruptedException

Write a buffer containing data replicated from the master onto the local persistence store.

Throws:

InterruptedException

IOException

sendHALogBuffer

Future<Void> sendHALogBuffer(IHALogRequest req,
                           IHAWriteMessage msg,
                           IBufferAccess b)
                             throws IOException,
                                    InterruptedException

Send an IHAWriteMessage and the associated raw buffer through the write pipeline.

Parameters:

req - The IHALogRequest for some HALog file.

msg - The IHAWriteMessage.

b - The raw buffer. Bytes from position to limit will be sent. remaining() must equal IHAWriteMessageBase.getSize().

Returns:

The Future for that request.

Throws:

IOException

InterruptedException

sendRawBuffer

Future<Void> sendRawBuffer(IHARebuildRequest req,
                         long sequence,
                         long quorumToken,
                         long fileExtent,
                         long offset,
                         int nbytes,
                         ByteBuffer b)
                           throws IOException,
                                  InterruptedException

Send an IHAWriteMessage and the associated raw buffer through the write pipeline.

Parameters:

req - The IHARebuildRequest to replicate the backing file to the requesting service.

sequence - The sequence of this IHAWriteMessage (origin ZERO (0)).

quorumToken - The quorum token of the leader, which must remain valid across the rebuild protocol.

fileExtent - The file extent as of the moment that the leader begins to replicate the existing backing file.

offset - The starting offset (relative to the root blocks).

nbytes - The #of bytes to be sent.

b - The raw buffer. The buffer will be cleared and filled with the specified data, then sent down the write pipeline.

Returns:

The Future for that request.

Throws:

IOException

InterruptedException

readFromLocalStore

ByteBuffer readFromLocalStore(long addr)
                              throws InterruptedException

Read from the local store in support of failover reads on nodes in a highly available Quorum.

Throws:

InterruptedException

setExtentForLocalStore

void setExtentForLocalStore(long extent)
                            throws IOException,
                                   InterruptedException

Extend local store for a highly available Quorum.

Throws:

InterruptedException

IOException

resetFromHARootBlock

void resetFromHARootBlock(IRootBlockView rootBlock)

Reload from the current root block - CAUTION : THIS IS NOT A RESET / ABORT. The purpose of this method is to reload the root block under some very limited circumstances, specifically when the root blocks were replaced during a REBUILD or RESYNC of the backing store for HA.

Note: This method is used when the root blocks of the leader are installed onto a follower. This can change the UUID for the backing store file. The IHABufferStrategy implementation MUST update any cached value for that UUID.

Use postHACommit(IRootBlockView) rather than this method in the 2-phase commit on the follower.

See Also:

Latency on followers during commit on leader

postHACommit

void postHACommit(IRootBlockView rootBlock)

Provides a trigger for synchronization of transient state after a commit.

For the RWStore this is used to resynchronize the allocators during the 2-phase commit on the follower with the delta in the allocators from the write set associated with that commit.

Parameters:

rootBlock - The newly installed root block.

See Also:

Latency on followers during commit on leader

getBlockSequence

long getBlockSequence()

Return the #of WriteCache blocks that were written out for the last write set. This is used to communicate the #of write cache blocks in the commit point back to AbstractJournal.commitNow(long). It is part of the commit protocol.

Note: This DOES NOT reflect the current value of the block sequence counter for ongoing writes. That counter is owned by the WriteCacheService.

See Also:

WriteCacheService.resetSequence(), FIXME I would prefer to expose the {@link WriteCacheService} to the {@link AbstractJournal} and let it directly invoke {@link WriteCacheService#resetSequence()}. The current pattern requires the {@link IHABufferStrategy} implementations to track the lastBlockSequence and is messy.

getCurrentBlockSequence

long getCurrentBlockSequence()

Return the then-current write cache block sequence.

See Also:

getBlockSequence()

snapshotAllocators

Object snapshotAllocators()

Snapshot the allocators in preparation for computing a digest of the committed allocations.

Returns:

The snapshot in a format that is backing store specific -or- null if the snapshot is a NOP for the IBufferStrategy (e.g., for the WORM).

computeDigest

void computeDigest(Object snapshot,
                 MessageDigest digest)
                   throws DigestException,
                          IOException

Compute the digest of the entire backing store (including the magic, file version, root blocks, etc).

Note: The digest is not reliable unless you either use a snapshot or suspend writes (on the quorum) while it is computed.

Parameters:

snapshot - The allocator snapshot (optional). When given, the digest is computed only for the snapshot. When null it is computed for the entire file.

Throws:

DigestException

IOException

readRaw

ByteBuffer readRaw(long fileOffset,
                 ByteBuffer transfer)

Used to support the rebuild protocol.

Parameters:

fileOffset - - absolute file offset

transfer - - target buffer for read

writeRawBuffer

void writeRawBuffer(HARebuildRequest req,
                  IHAWriteMessage msg,
                  ByteBuffer transfer)
                    throws IOException

Used to support the rebuild protocol

Parameters:

req -

msg -

transfer -

Throws:

IOException

writeOnStream

void writeOnStream(OutputStream os,
                 AbstractJournal.ISnapshotData coreData,
                 Quorum<HAGlue,QuorumService<HAGlue>> quorum,
                 long token)
                   throws IOException,
                          QuorumException

Write a consistent snapshot of the committed state of the backing store. This method writes all data starting after the root blocks. The caller is responsible for putting down the root blocks themselves.

Note: The caller is able to obtain both root blocks atomically, while the strategy may not be aware of the root blocks or may not be able to coordinate their atomic capture.

Note: The caller must ensure that the resulting snapshot will be consistent either by ensuring that no writes occur or by taking a read-lock that will prevent overwrites of committed state during this operation.

Parameters:

os - Where to write the data.

quorum - The Quorum.

token - The token that must remain valid during this operation.

Throws:

IOException

QuorumException - if the service is not joined with the met quorum for that token at any point during the operation.

getWriteCacheService

WriteCacheService getWriteCacheService()

Return the WriteCacheService (mainly for debugging).

getStoreState

StoreState getStoreState()

A StoreState object references critical transient data that can be used to determine a degree of consistency between stores, specifically for an HA context.