WORMStrategy (Blazegraph Database Platform 2.1.5 API)

java.lang.Object
- com.bigdata.rawstore.AbstractRawStore
- - com.bigdata.rawstore.AbstractRawWormStore
  - - com.bigdata.journal.AbstractBufferStrategy
    - - com.bigdata.journal.WORMStrategy

All Implemented Interfaces:

ICounterSetAccess, IBackingReader, IBufferStrategy, IDiskBasedStrategy, IHABufferStrategy, IAddressManager, IMRMW, IMROW, IRawStore, IStreamStore, IWORM
```
public class WORMStrategy
extends AbstractBufferStrategy
implements IDiskBasedStrategy, IHABufferStrategy, IBackingReader
```
Disk-based Write Once Read Many (WORM) journal strategy. The phsyical layout on the disk is the journal header, the root blocks, and then the user extent.
Writes are buffered in a write cache. The cache is flushed when it would overflow. As a result only large sequential writes are performed on the store. Reads read through the write cache for consistency.
Note: This is used to realize both the BufferMode.Disk and the BufferMode.Temporary BufferModes. When configured for the BufferMode.Temporary mode: the root blocks will not be written onto the disk, writes will not be forced, and the backing file will be created the first time the DiskOnlyStrategy attempts to write through to the disk. For many scenarios, the backing file will never be created unless the write cache overflows. This provides very low latency on start-up, the same MRMW capability, and allows very large temporary stores. FIXME Examine behavior when write caching is enabled/disabled for the OS. This has a profound impact. Asynchronous writes of multiple buffers, and the use of smaller buffers, may be absolutely when the write cache is disabled. It may be that swapping sets in because the Windows write cache is being overworked, in which case doing incremental and async IO would help. Compare with behavior on server platforms. See http://support.microsoft.com/kb/259716, http://www.accucadd.com/TechNotes/Cache/WriteBehindCache.htm, http://msdn2.microsoft.com/en-us/library/aa365165.aspx, http://www.jasonbrome.com/blog/archives/2004/04/03/writecache_enabled.html, http://support.microsoft.com/kb/811392, http://mail-archives.apache.org/mod_mbox /db-derby-dev/200609.mbox/%3C44F820A8.6000000@sun.com%3E
```
                /sbin/hdparm -W 0 /dev/hda 0 Disable write caching
                /sbin/hdparm -W 1 /dev/hda 1 Enable write caching
 
```
Version:

$Id$

Author:

Bryan Thompson

See Also:
BufferMode.Disk, BufferMode.Temporary

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`WORMStrategy.StoreCounters<T extends WORMStrategy.StoreCounters<T>>` Striped performance counters for `IRawStore` access, including operations that read or write through to the underlying media.
`static class`	`WORMStrategy.WormStoreState`

Field Summary
- Fields inherited from class com.bigdata.journal.AbstractBufferStrategy
  bufferMode, commitOffset, ERR_ADDRESS_IS_NULL, ERR_ADDRESS_NOT_WRITTEN, ERR_BAD_RECORD_SIZE, ERR_BUFFER_EMPTY, ERR_BUFFER_NULL, ERR_BUFFER_OVERRUN, ERR_MAX_EXTENT, ERR_NOT_OPEN, ERR_OPEN, ERR_READ_ONLY, ERR_RECORD_LENGTH_ZERO, ERR_TRUNCATE, initialExtent, log, maximumExtent, nextOffset, WARN
- Fields inherited from class com.bigdata.rawstore.AbstractRawWormStore
  am
- Fields inherited from interface com.bigdata.rawstore.IAddressManager
  NULL

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`abort()` Resets the `WriteCacheService` (if enabled).
`void`	`close()` Closes the file immediately (without flushing any pending writes).
`void`	`closeForWrites()` Extended to reset the write cache.
`void`	`commit()` A method that removes assumptions of how a specific strategy commits data.
`void`	`computeDigest(Object snapshot, MessageDigest digest)` Compute the digest of the entire backing store (including the magic, file version, root blocks, etc).
`void`	`delete(long addr)` This implementation can not release storage allocations and invocations of this method are ignored.
`void`	`deleteResources()` Deletes the backing file(s) (if any).
`void`	`force(boolean metadata)` Force the data to stable storage.
`long`	`getBlockSequence()` Return the #of `WriteCache` blocks that were written out for the last write set.
`FileChannel`	`getChannel()` Note: This MAY be `null`.
`CounterSet`	`getCounters()` Return interesting information about the write cache and file operations.
`long`	`getCurrentBlockSequence()` Return the then-current write cache block sequence.
`long`	`getExtent()` The current size of the journal in bytes.
`File`	`getFile()` The backing file.
`int`	`getHeaderSize()` The size of the file header in bytes.
`protected long`	`getMinimumExtension()` Overridden to use the value specified to the constructor.
`RandomAccessFile`	`getRandomAccessFile()` Note: This MAY be `null`.
`WORMStrategy.StoreCounters<?>`	`getStoreCounters()` Returns the striped performance counters for the store.
`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.
`long`	`getUserExtent()` The size of the user data extent in bytes.
`com.bigdata.journal.WORMStrategy.WORMWriteCacheService`	`getWriteCacheService()` Return the `WriteCacheService` (mainly for debugging).
`boolean`	`isFullyBuffered()` True iff the store is fully buffered (all reads are against memory).
`boolean`	`isStable()` True iff backed by stable storage.
`void`	`postHACommit(IRootBlockView rootBlock)` Provides a trigger for synchronization of transient state after a commit.
`ByteBuffer`	`read(long addr)` Extended to handle `ChecksumError`s by reading on another node when the `Quorum` (iff the quorum is highly available).
`ByteBuffer`	`readFromLocalStore(long addr)` Read from the local store in support of failover reads on nodes in a highly available `Quorum`.
`ByteBuffer`	`readRaw(long offset, ByteBuffer dst)` Read on the backing file.
`ByteBuffer`	`readRootBlock(boolean rootBlock0)` Read the specified root block from the backing file.
`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`.
`void`	`setStoreCounters(WORMStrategy.StoreCounters<?> storeCounters)` Replaces the `WORMStrategy.StoreCounters` object.
`Object`	`snapshotAllocators()` Snapshot the allocators in preparation for computing a digest of the committed allocations.
`long`	`transferTo(RandomAccessFile out)` A block operation that transfers the serialized records (aka the written on portion of the user extent) en mass from the buffer onto an output file.
`void`	`truncate(long newExtent)` Either truncates or extends the journal.
`boolean`	`useChecksums()` `false` by default since these were added for HA with the `WORMStrategy` and the `RWStrategy`.
`long`	`write(ByteBuffer data)` Write the data (unisolated).
`void`	`writeOnStream(OutputStream os, AbstractJournal.ISnapshotData snapshotData, 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.
`void`	`writeRootBlock(IRootBlockView rootBlock, ForceEnum forceOnCommit)` Write the root block onto stable storage (ie, flush it through to disk).

Methods inherited from class com.bigdata.journal.AbstractBufferStrategy
assertOpen, destroy, getBufferMode, getInitialExtent, getMaximumExtent, getMaxRecordSize, getMetaBitsAddr, getMetaStartAddr, getNextOffset, getResourceMetadata, getUUID, isDirty, isOpen, isReadOnly, overflow, requiresCommit, size, transferFromDiskTo

Methods inherited from class com.bigdata.rawstore.AbstractRawWormStore
getAddressManager, getByteCount, getOffset, getOffsetBits, getPhysicalAddress, toAddr, toString

Methods inherited from class com.bigdata.rawstore.AbstractRawStore
getInputStream, getOutputStream

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.bigdata.journal.IBufferStrategy
getAddressManager, getBufferMode, getInitialExtent, getMaximumExtent, getMaxRecordSize, getMetaBitsAddr, getMetaStartAddr, getNextOffset, getOffsetBits, isDirty, requiresCommit

Methods inherited from interface com.bigdata.rawstore.IRawStore
destroy, getResourceMetadata, getUUID, isOpen, isReadOnly, size

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
  - getWriteCacheService
```
public com.bigdata.journal.WORMStrategy.WORMWriteCacheService getWriteCacheService()
```
    Description copied from interface: IHABufferStrategy
    
    Return the WriteCacheService (mainly for debugging).
    
    Specified by:
    
    getWriteCacheService in interface IHABufferStrategy
  - useChecksums
```
public boolean useChecksums()
```
    Description copied from class: AbstractBufferStrategy
    
    false by default since these were added for HA with the WORMStrategy and the RWStrategy.
    
    Specified by:
    
    useChecksums in interface IBufferStrategy
    
    Overrides:
    
    useChecksums in class AbstractBufferStrategy
  - getHeaderSize
```
public final int getHeaderSize()
```
    Description copied from interface: IDiskBasedStrategy
    
    The size of the file header in bytes.
    
    Specified by:
    
    getHeaderSize in interface IBufferStrategy
    
    Specified by:
    
    getHeaderSize in interface IDiskBasedStrategy
  - getFile
```
public final File getFile()
```
    Description copied from interface: IDiskBasedStrategy
    
    The backing file.
    
    Specified by:
    
    getFile in interface IDiskBasedStrategy
    
    Specified by:
    
    getFile in interface IRawStore
  - getRandomAccessFile
```
public final RandomAccessFile getRandomAccessFile()
```
    Note: This MAY be null. If BufferMode.Temporary is used then it WILL be null until the #writeCache is flushed to disk for the first time.
    
    Specified by:
    
    getRandomAccessFile in interface IDiskBasedStrategy
  - getChannel
```
public final FileChannel getChannel()
```
    Note: This MAY be null. If BufferMode.Temporary is used then it WILL be null until the #writeCache is flushed to disk for the first time.
    
    Specified by:
    
    getChannel in interface IDiskBasedStrategy
  - getStoreCounters
```
public WORMStrategy.StoreCounters<?> getStoreCounters()
```
    Returns the striped performance counters for the store.
  - setStoreCounters
```
public void setStoreCounters(WORMStrategy.StoreCounters<?> storeCounters)
```
    Replaces the WORMStrategy.StoreCounters object.
    
    Parameters:
    storeCounters - The new BTree.Counters.
    
    Throws:
    
    IllegalArgumentException - if the argument is null.
  - getCounters
```
public CounterSet getCounters()
```
    Return interesting information about the write cache and file operations.
    
    Specified by:
    
    getCounters in interface ICounterSetAccess
    
    Specified by:
    
    getCounters in interface IBufferStrategy
  - isStable
```
public final boolean isStable()
```
    Description copied from interface: IRawStore
    
    True iff backed by stable storage.
    
    Specified by:
    
    isStable in interface IRawStore
  - isFullyBuffered
```
public boolean isFullyBuffered()
```
    Description copied from interface: IRawStore
    
    True iff the store is fully buffered (all reads are against memory). Implementations MAY change the value returned by this method over the life cycle of the store, e.g., to conserve memory a store may drop or decrease its buffer if it is backed by disk.
    Note: This does not guarantee that the OS will not swap the buffer onto disk.
    
    Specified by:
    
    isFullyBuffered in interface IRawStore
  - force
```
public void force(boolean metadata)
```
    Description copied from interface: IRawStore
    
    Force the data to stable storage. While this is NOT sufficient to guarantee an atomic commit, the data must be forced to disk as part of an atomic commit protocol.
    
    Specified by:
    
    force in interface IRawStore
    
    Parameters:
    metadata - If true, then force both the file contents and the file metadata to disk.
  - commit
```
public void commit()
```
    A method that removes assumptions of how a specific strategy commits data. For most strategies the action is void since the client WORM DISK strategy writes data as allocated. For the Read Write Strategy more data must be managed as part of the protocol outside of the RootBlock, and this is the method that triggers that management. The caller MUST provide appropriate synchronization.
    This implementation flushes the write cache (if enabled).
    
    Specified by:
    
    commit in interface IBufferStrategy
    
    Overrides:
    
    commit in class AbstractBufferStrategy
  - getBlockSequence
```
public long getBlockSequence()
```
    Description copied from interface: IHABufferStrategy
    
    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.
    
    Specified by:
    
    getBlockSequence in interface IHABufferStrategy
    
    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
```
public long getCurrentBlockSequence()
```
    Description copied from interface: IHABufferStrategy
    
    Return the then-current write cache block sequence.
    
    Specified by:
    
    getCurrentBlockSequence in interface IHABufferStrategy
    
    See Also:
    IHABufferStrategy.getBlockSequence()
  - abort
```
public void abort()
```
    Resets the WriteCacheService (if enabled).
    Note: This assumes the caller is synchronized appropriately otherwise writes belonging to other threads will be discarded from the cache!
    
    Specified by:
    
    abort in interface IBufferStrategy
    
    Overrides:
    
    abort in class AbstractBufferStrategy
  - close
```
public void close()
```
    Closes the file immediately (without flushing any pending writes).
    
    Specified by:
    
    close in interface IRawStore
    
    Overrides:
    
    close in class AbstractBufferStrategy
  - deleteResources
```
public void deleteResources()
```
    Description copied from interface: IRawStore
    
    Deletes the backing file(s) (if any).
    
    Specified by:
    
    deleteResources in interface IRawStore
  - getExtent
```
public final long getExtent()
```
    Description copied from interface: IBufferStrategy
    
    The current size of the journal in bytes. When the journal is backed by a disk file this is the actual size on disk of that file. The initial value for this property is set by Options.INITIAL_EXTENT.
    
    Specified by:
    
    getExtent in interface IBufferStrategy
  - getUserExtent
```
public final long getUserExtent()
```
    Description copied from interface: IBufferStrategy
    
    The size of the user data extent in bytes.
    Note: The size of the user extent is always generally smaller than the value reported by IBufferStrategy.getExtent() since the latter also reports the space allocated to the journal header and root blocks.
    
    Specified by:
    
    getUserExtent in interface IBufferStrategy
  - read
```
public ByteBuffer read(long addr)
```
    Extended to handle ChecksumErrors by reading on another node when the Quorum (iff the quorum is highly available).
    Read the data (unisolated).
    
    Specified by:
    
    read in interface IRawStore
    
    Parameters:
    addr - A long integer that encodes both the offset from which the data will be read and the #of bytes to be read. See IAddressManager.toAddr(int, long).
    
    Returns:
    The data read. The buffer will be flipped to prepare for reading (the position will be zero and the limit will be the #of bytes read).
  - readFromLocalStore
```
public ByteBuffer readFromLocalStore(long addr)
                              throws InterruptedException
```
    Read from the local store in support of failover reads on nodes in a highly available Quorum.
    This implementation tests the WriteCacheService first and then reads through to the local disk on a cache miss. This is automatically invoked by read(long).
    
    Specified by:
    
    readFromLocalStore in interface IHABufferStrategy
    
    Throws:
    
    InterruptedException
  - readRaw
```
public ByteBuffer readRaw(long offset,
                 ByteBuffer dst)
```
    Read on the backing file. Buffer.remaining() bytes will be read into the caller's buffer, starting at the specified offset in the backing file.
    
    Specified by:
    
    readRaw in interface IBackingReader
    
    Specified by:
    
    readRaw in interface IHABufferStrategy
    
    Parameters:
    offset - The offset of the first byte (now absolute, not relative to the start of the data region).
    dst - Where to put the data. Bytes will be written at position until limit.
    
    Returns:
    The caller's buffer, prepared for reading.
  - write
```
public long write(ByteBuffer data)
```
    Description copied from interface: IRawStore
    
    Write the data (unisolated).
    
    Specified by:
    
    write in interface IRawStore
    
    Parameters:
    data - The data. The bytes from the current Buffer.position() to the Buffer.limit() will be written and the Buffer.position() will be advanced to the Buffer.limit() . The caller may subsequently modify the contents of the buffer without changing the state of the store (i.e., the data are copied into the store).
    
    Returns:
    A long integer formed that encodes both the offset from which the data may be read and the #of bytes to be read. See IAddressManager.
  - getMinimumExtension
```
protected long getMinimumExtension()
```
    Overridden to use the value specified to the constructor.
    
    Overrides:
    
    getMinimumExtension in class AbstractBufferStrategy
  - readRootBlock
```
public ByteBuffer readRootBlock(boolean rootBlock0)
```
    Description copied from interface: IBufferStrategy
    
    Read the specified root block from the backing file.
    
    Specified by:
    
    readRootBlock in interface IBufferStrategy
  - writeRootBlock
```
public void writeRootBlock(IRootBlockView rootBlock,
                  ForceEnum forceOnCommit)
```
    Description copied from interface: IBufferStrategy
    
    Write the root block onto stable storage (ie, flush it through to disk).
    
    Specified by:
    
    writeRootBlock in interface IBufferStrategy
    
    Parameters:
    rootBlock - The root block. Which root block is indicated by IRootBlockView.isRootBlock0().
  - truncate
```
public void truncate(long newExtent)
```
    Description copied from interface: IBufferStrategy
    
    Either truncates or extends the journal.
    Note: Implementations of this method MUST be synchronized so that the operation is atomic with respect to concurrent writers.
    
    Specified by:
    
    truncate in interface IBufferStrategy
    
    Parameters:
    newExtent - The new extent of the journal. This value represent the total extent of the journal, including any root blocks together with the user extent.
  - transferTo
```
public long transferTo(RandomAccessFile out)
                throws IOException
```
    Description copied from interface: IBufferStrategy
    
    A block operation that transfers the serialized records (aka the written on portion of the user extent) en mass from the buffer onto an output file. The buffered records are written "in order" starting at the current position on the output file. The file is grown if necessary. The file position is advanced to the last byte written on the file.
    Note: Implementations of this method MUST be synchronized so that the operation is atomic with respect to concurrent writers.
    
    Specified by:
    
    transferTo in interface IBufferStrategy
    
    Parameters:
    out - The file to which the buffer contents will be transferred.
    
    Returns:
    The #of bytes written.
    
    Throws:
    
    IOException
  - closeForWrites
```
public void closeForWrites()
```
    Extended to reset the write cache.
    Note: The file is NOT closed and re-opened in a read-only mode in order to avoid causing difficulties for concurrent readers.
    
    Specified by:
    
    closeForWrites in interface IBufferStrategy
    
    Overrides:
    
    closeForWrites in class AbstractBufferStrategy
  - delete
```
public void delete(long addr)
```
    This implementation can not release storage allocations and invocations of this method are ignored.
    
    Specified by:
    
    delete in interface IRawStore
    
    Overrides:
    
    delete in class AbstractBufferStrategy
    
    Parameters:
    addr - A long integer formed using Addr that encodes both the offset at which the data was written and the #of bytes that were written.
  - writeRawBuffer
```
public void writeRawBuffer(IHAWriteMessage msg,
                  IBufferAccess b)
                    throws IOException,
                           InterruptedException
```
    Description copied from interface: IHABufferStrategy
    
    Write a buffer containing data replicated from the master onto the local persistence store.
    
    Specified by:
    
    writeRawBuffer in interface IHABufferStrategy
    
    Throws:
    
    IOException
    
    InterruptedException
  - sendHALogBuffer
```
public Future<Void> sendHALogBuffer(IHALogRequest req,
                           IHAWriteMessage msg,
                           IBufferAccess b)
                             throws IOException,
                                    InterruptedException
```
    Description copied from interface: IHABufferStrategy
    
    Send an IHAWriteMessage and the associated raw buffer through the write pipeline.
    
    Specified by:
    
    sendHALogBuffer in interface IHABufferStrategy
    
    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
```
public Future<Void> sendRawBuffer(IHARebuildRequest req,
                         long sequence,
                         long quorumToken,
                         long fileExtent,
                         long offset,
                         int nbytes,
                         ByteBuffer b)
                           throws IOException,
                                  InterruptedException
```
    Description copied from interface: IHABufferStrategy
    
    Send an IHAWriteMessage and the associated raw buffer through the write pipeline.
    
    Specified by:
    
    sendRawBuffer in interface IHABufferStrategy
    
    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
  - writeOnStream
```
public void writeOnStream(OutputStream os,
                 AbstractJournal.ISnapshotData snapshotData,
                 Quorum<HAGlue,QuorumService<HAGlue>> quorum,
                 long token)
                   throws IOException,
                          QuorumException
```
    Description copied from interface: IHABufferStrategy
    
    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.
    
    Specified by:
    
    writeOnStream in interface IHABufferStrategy
    
    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.
  - setExtentForLocalStore
```
public void setExtentForLocalStore(long extent)
                            throws IOException,
                                   InterruptedException
```
    Description copied from interface: IHABufferStrategy
    
    Extend local store for a highly available Quorum.
    
    Specified by:
    
    setExtentForLocalStore in interface IHABufferStrategy
    
    Throws:
    
    InterruptedException
    
    IOException
  - resetFromHARootBlock
```
public void resetFromHARootBlock(IRootBlockView rootBlock)
```
    Description copied from interface: IHABufferStrategy
    
    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 IHABufferStrategy.postHACommit(IRootBlockView) rather than this method in the 2-phase commit on the follower.
    
    Specified by:
    
    resetFromHARootBlock in interface IHABufferStrategy
    
    See Also:
    Latency on followers during commit on leader
  - postHACommit
```
public void postHACommit(IRootBlockView rootBlock)
```
    Description copied from interface: IHABufferStrategy
    
    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.
    
    Specified by:
    
    postHACommit in interface IHABufferStrategy
    
    Parameters:
    rootBlock - The newly installed root block.
    See Also:
    Latency on followers during commit on leader
  - snapshotAllocators
```
public Object snapshotAllocators()
```
    Description copied from interface: IHABufferStrategy
    
    Snapshot the allocators in preparation for computing a digest of the committed allocations.
    
    Specified by:
    
    snapshotAllocators in interface IHABufferStrategy
    
    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
```
public void computeDigest(Object snapshot,
                 MessageDigest digest)
                   throws DigestException,
                          IOException
```
    Description copied from interface: IHABufferStrategy
    
    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.
    
    Specified by:
    
    computeDigest in interface IHABufferStrategy
    
    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
  - writeRawBuffer
```
public void writeRawBuffer(HARebuildRequest req,
                  IHAWriteMessage msg,
                  ByteBuffer transfer)
                    throws IOException
```
    Description copied from interface: IHABufferStrategy
    
    Used to support the rebuild protocol
    
    Specified by:
    
    writeRawBuffer in interface IHABufferStrategy
    
    Throws:
    
    IOException
  - getStoreState
```
public StoreState getStoreState()
```
    Description copied from interface: IHABufferStrategy
    
    A StoreState object references critical transient data that can be used to determine a degree of consistency between stores, specifically for an HA context.
    
    Specified by:
    
    getStoreState in interface IHABufferStrategy

Class WORMStrategy

Nested Class Summary

Field Summary

Fields inherited from class com.bigdata.journal.AbstractBufferStrategy

Fields inherited from class com.bigdata.rawstore.AbstractRawWormStore

Fields inherited from interface com.bigdata.rawstore.IAddressManager

Method Summary

Methods inherited from class com.bigdata.journal.AbstractBufferStrategy

Methods inherited from class com.bigdata.rawstore.AbstractRawWormStore

Methods inherited from class com.bigdata.rawstore.AbstractRawStore

Methods inherited from class java.lang.Object

Methods inherited from interface com.bigdata.journal.IBufferStrategy

Methods inherited from interface com.bigdata.rawstore.IRawStore

Methods inherited from interface com.bigdata.rawstore.IAddressManager

Methods inherited from interface com.bigdata.rawstore.IStreamStore

Method Detail

getWriteCacheService

useChecksums

getHeaderSize

getFile

getRandomAccessFile

getChannel

getStoreCounters

setStoreCounters

getCounters

isStable

isFullyBuffered

force

commit

getBlockSequence

getCurrentBlockSequence

abort

close

deleteResources

getExtent

getUserExtent

read

readFromLocalStore

readRaw

write

getMinimumExtension

readRootBlock

writeRootBlock

truncate

transferTo

closeForWrites

delete

writeRawBuffer

sendHALogBuffer

sendRawBuffer

writeOnStream

setExtentForLocalStore

resetFromHARootBlock

postHACommit

snapshotAllocators

computeDigest

writeRawBuffer

getStoreState