org.apache.hadoop.hbase.regionserver.wal

Interface HLog

@InterfaceAudience.Private
public interface HLog

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	HLog.Entry Utility class that lets us keep track of the edit with it's key.
static interface	HLog.Reader
static interface	HLog.Writer

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_WAL_TRAILER_WARN_SIZE
static Pattern	EDITFILES_NAME_PATTERN
static org.apache.commons.logging.Log	LOG
static String	META_HLOG_FILE_EXTN The hbase:meta region's HLog filename extension
static String	RECOVERED_LOG_TMPFILE_SUFFIX
static boolean	SPLIT_SKIP_ERRORS_DEFAULT
static String	SPLITTING_EXT File Extension used while splitting an HLog into regions (HBASE-2312)
static String	WAL_TRAILER_WARN_SIZE Configuration name of HLog Trailer's warning size.

Method Summary

Methods

Modifier and Type	Method and Description
void	abortCacheFlush(byte[] encodedRegionName) Abort a cache flush.
void	append(HRegionInfo info, TableName tableName, WALEdit edits, long now, HTableDescriptor htd, AtomicLong sequenceId) Same as appendNoSync(HRegionInfo, TableName, WALEdit, List, long, HTableDescriptor), except it causes a sync on the log
long	appendNoSync(HRegionInfo info, TableName tableName, WALEdit edits, List<UUID> clusterIds, long now, HTableDescriptor htd, AtomicLong sequenceId, boolean isInMemstore, long nonceGroup, long nonce) Append a set of edits to the log.
void	close() Shut down the log.
void	closeAndDelete() Shut down the log and delete the log directory
void	completeCacheFlush(byte[] encodedRegionName) Complete the cache flush.
WALCoprocessorHost	getCoprocessorHost()
long	getEarliestMemstoreSeqNum(byte[] encodedRegionName) Gets the earliest sequence number in the memstore for this particular region.
long	getFilenum()
long	getLogFileSize()
int	getNumLogFiles()
void	hflush()
void	hsync()
boolean	isLowReplicationRollEnabled() Get LowReplication-Roller status
void	postAppend(List<HLog.Entry> entries) For notification post append to the writer.
void	postSync() For notification post writer sync.
void	registerWALActionsListener(WALActionsListener listener) registers WALActionsListener
byte[][]	rollWriter() Roll the log writer.
byte[][]	rollWriter(boolean force) Roll the log writer.
boolean	startCacheFlush(byte[] encodedRegionName) WAL keeps track of the sequence numbers that were not yet flushed from memstores in order to be able to do cleanup.
void	sync()
void	sync(long txid)
boolean	unregisterWALActionsListener(WALActionsListener listener) unregisters WALActionsListener

Field Detail

LOG

static final org.apache.commons.logging.Log LOG

SPLITTING_EXT

static final String SPLITTING_EXT

File Extension used while splitting an HLog into regions (HBASE-2312)

See Also:

Constant Field Values

SPLIT_SKIP_ERRORS_DEFAULT

static final boolean SPLIT_SKIP_ERRORS_DEFAULT

See Also:

Constant Field Values

META_HLOG_FILE_EXTN

static final String META_HLOG_FILE_EXTN

The hbase:meta region's HLog filename extension

See Also:

Constant Field Values

WAL_TRAILER_WARN_SIZE

static final String WAL_TRAILER_WARN_SIZE

Configuration name of HLog Trailer's warning size. If a waltrailer's size is greater than the configured size, a warning is logged. This is used with Protobuf reader/writer.

See Also:

Constant Field Values

DEFAULT_WAL_TRAILER_WARN_SIZE

static final int DEFAULT_WAL_TRAILER_WARN_SIZE

See Also:

Constant Field Values

EDITFILES_NAME_PATTERN

static final Pattern EDITFILES_NAME_PATTERN

RECOVERED_LOG_TMPFILE_SUFFIX

static final String RECOVERED_LOG_TMPFILE_SUFFIX

See Also:

Constant Field Values

Method Detail

registerWALActionsListener

void registerWALActionsListener(WALActionsListener listener)

registers WALActionsListener

Parameters:

listener -

unregisterWALActionsListener

boolean unregisterWALActionsListener(WALActionsListener listener)

unregisters WALActionsListener

Parameters:

listener -

getFilenum

long getFilenum()

Returns:

Current state of the monotonically increasing file id.

getNumLogFiles

int getNumLogFiles()

Returns:

the number of HLog files

getLogFileSize

long getLogFileSize()

Returns:

the size of HLog files

rollWriter

byte[][] rollWriter()
                    throws FailedLogCloseException,
                           IOException

Roll the log writer. That is, start writing log messages to a new file.

The implementation is synchronized in order to make sure there's one rollWriter running at any given time.

Returns:

If lots of logs, flush the returned regions so next time through we can clean logs. Returns null if nothing to flush. Names are actual region names as returned by HRegionInfo.getEncodedName()

Throws:

FailedLogCloseException

IOException

rollWriter

byte[][] rollWriter(boolean force)
                    throws FailedLogCloseException,
                           IOException

Roll the log writer. That is, start writing log messages to a new file.

The implementation is synchronized in order to make sure there's one rollWriter running at any given time.

Parameters:

force - If true, force creation of a new writer even if no entries have been written to the current writer

Returns:

If lots of logs, flush the returned regions so next time through we can clean logs. Returns null if nothing to flush. Names are actual region names as returned by HRegionInfo.getEncodedName()

Throws:

FailedLogCloseException

IOException

close

void close()
           throws IOException

Shut down the log.

Throws:

IOException

closeAndDelete

void closeAndDelete()
                    throws IOException

Shut down the log and delete the log directory

Throws:

IOException

append

void append(HRegionInfo info,
          TableName tableName,
          WALEdit edits,
          long now,
          HTableDescriptor htd,
          AtomicLong sequenceId)
            throws IOException

Same as appendNoSync(HRegionInfo, TableName, WALEdit, List, long, HTableDescriptor), except it causes a sync on the log

Parameters:

sequenceId - of the region.

Throws:

IOException

postAppend

void postAppend(List<HLog.Entry> entries)

For notification post append to the writer.

Parameters:

entries -

postSync

void postSync()

For notification post writer sync.

appendNoSync

long appendNoSync(HRegionInfo info,
                TableName tableName,
                WALEdit edits,
                List<UUID> clusterIds,
                long now,
                HTableDescriptor htd,
                AtomicLong sequenceId,
                boolean isInMemstore,
                long nonceGroup,
                long nonce)
                  throws IOException

Append a set of edits to the log. Log edits are keyed by (encoded) regionName, rowname, and log-sequence-id. The HLog is not flushed after this transaction is written to the log.

Parameters:

info -

tableName -

edits -

clusterIds - The clusters that have consumed the change (for replication)

now -

htd -

sequenceId - of the region

Returns:

txid of this transaction

Throws:

IOException

hsync

void hsync()
           throws IOException

Throws:

IOException

hflush

void hflush()
            throws IOException

Throws:

IOException

sync

void sync()
          throws IOException

Throws:

IOException

sync

void sync(long txid)
          throws IOException

Throws:

IOException

startCacheFlush

boolean startCacheFlush(byte[] encodedRegionName)

WAL keeps track of the sequence numbers that were not yet flushed from memstores in order to be able to do cleanup. This method tells WAL that some region is about to flush memstore. We stash the oldest seqNum for the region, and let the the next edit inserted in this region be recorded in append(HRegionInfo, TableName, WALEdit, long, HTableDescriptor, AtomicLong) as new oldest seqnum. In case of flush being aborted, we put the stashed value back; in case of flush succeeding, the seqNum of that first edit after start becomes the valid oldest seqNum for this region.

Returns:

true if the flush can proceed, false in case wal is closing (ususally, when server is closing) and flush couldn't be started.

completeCacheFlush

void completeCacheFlush(byte[] encodedRegionName)

Complete the cache flush.

Parameters:

encodedRegionName - Encoded region name.

abortCacheFlush

void abortCacheFlush(byte[] encodedRegionName)

Abort a cache flush. Call if the flush fails. Note that the only recovery for an aborted flush currently is a restart of the regionserver so the snapshot content dropped by the failure gets restored to the memstore.v

Parameters:

encodedRegionName - Encoded region name.

getCoprocessorHost

WALCoprocessorHost getCoprocessorHost()

Returns:

Coprocessor host.

isLowReplicationRollEnabled

boolean isLowReplicationRollEnabled()

Get LowReplication-Roller status

Returns:

lowReplicationRollEnabled

getEarliestMemstoreSeqNum

long getEarliestMemstoreSeqNum(byte[] encodedRegionName)

Gets the earliest sequence number in the memstore for this particular region. This can serve as best-effort "recent" WAL number for this region.

Parameters:

encodedRegionName - The region to get the number for.

Returns:

The number if present, HConstants.NO_SEQNUM if absent.