org.apache.hadoop.hbase.master.snapshot

Class TakeSnapshotHandler

java.lang.Object

org.apache.hadoop.hbase.executor.EventHandler

org.apache.hadoop.hbase.master.snapshot.TakeSnapshotHandler

All Implemented Interfaces:

Comparable<Runnable>, Runnable, ForeignExceptionSnare, SnapshotSentinel

Direct Known Subclasses:

DisabledTableSnapshotHandler, EnabledTableSnapshotHandler

@InterfaceAudience.Private
public abstract class TakeSnapshotHandler
extends EventHandler
implements SnapshotSentinel, ForeignExceptionSnare

A handler for taking snapshots from the master. This is not a subclass of TableEventHandler because using that would incur an extra hbase:meta scan. The snapshotRegions(List) call should get implemented for each snapshot flavor.

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.hadoop.conf.Configuration	conf
protected org.apache.hadoop.fs.FileSystem	fs
protected TableDescriptor	htd
protected MasterServices	master
protected MetricsSnapshot	metricsSnapshot
protected ForeignExceptionDispatcher	monitor
protected org.apache.hadoop.fs.Path	rootDir
protected SnapshotProtos.SnapshotDescription	snapshot
protected SnapshotManager	snapshotManager
protected SnapshotManifest	snapshotManifest
protected TableName	snapshotTable
protected MonitoredTask	status
protected org.apache.hadoop.fs.Path	workingDir

Fields inherited from class org.apache.hadoop.hbase.executor.EventHandler

eventType, seqids, server, waitingTimeForEvents

Constructor Summary

Constructors

Constructor and Description
TakeSnapshotHandler(SnapshotProtos.SnapshotDescription snapshot, MasterServices masterServices, SnapshotManager snapshotManager)

Method Summary

Modifier and Type	Method and Description
void	cancel(String why) Actively cancel a running snapshot.
void	completeSnapshot(org.apache.hadoop.fs.Path snapshotDir, org.apache.hadoop.fs.Path workingDir, org.apache.hadoop.fs.FileSystem fs) Reset the manager to allow another snapshot to proceed
protected abstract boolean	downgradeToSharedTableLock() When taking snapshot, first we must acquire the exclusive table lock to confirm that there are no ongoing merge/split procedures.
long	getCompletionTimestamp()
ForeignException	getException() Get the value of the captured exception.
ForeignException	getExceptionIfFailed() Get the exception that caused the snapshot to fail, if the snapshot has failed.
SnapshotProtos.SnapshotDescription	getSnapshot()
boolean	hasException() Non-exceptional form of ForeignExceptionSnare.rethrowException().
boolean	isFinished() Check to see if the snapshot is finished, where finished may be success or failure.
TakeSnapshotHandler	prepare() Event handlers should do all the necessary checks in this method (rather than in the constructor, or in process()) so that the caller, which is mostly executed in the ipc context can fail fast.
void	process() Execute the core common portions of taking a snapshot.
void	rethrowException() Rethrow an exception currently held by the ForeignExceptionSnare.
void	rethrowExceptionIfFailed() Rethrow the exception returned by SnapshotSentinel.getExceptionIfFailed().
protected void	snapshotDisabledRegion(RegionInfo regionInfo) Take a snapshot of the specified disabled region
protected abstract void	snapshotRegions(List<Pair<RegionInfo,ServerName>> regions) Snapshot the specified regions

Methods inherited from class org.apache.hadoop.hbase.executor.EventHandler

compareTo, getEventType, getInformativeName, getPriority, getSeqid, handleException, run, toString

Methods inherited from class java.lang.Object

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

Field Detail

master

protected final MasterServices master

metricsSnapshot

protected final MetricsSnapshot metricsSnapshot

snapshot

protected final SnapshotProtos.SnapshotDescription snapshot

conf

protected final org.apache.hadoop.conf.Configuration conf

fs

protected final org.apache.hadoop.fs.FileSystem fs

rootDir

protected final org.apache.hadoop.fs.Path rootDir

workingDir

protected final org.apache.hadoop.fs.Path workingDir

monitor

protected final ForeignExceptionDispatcher monitor

status

protected final MonitoredTask status

snapshotTable

protected final TableName snapshotTable

snapshotManifest

protected final SnapshotManifest snapshotManifest

snapshotManager

protected final SnapshotManager snapshotManager

htd

protected TableDescriptor htd

Constructor Detail

TakeSnapshotHandler

public TakeSnapshotHandler(SnapshotProtos.SnapshotDescription snapshot,
                           MasterServices masterServices,
                           SnapshotManager snapshotManager)

Parameters:

snapshot - descriptor of the snapshot to take

masterServices - master services provider

Method Detail

prepare

public TakeSnapshotHandler prepare()
                            throws Exception

Description copied from class: EventHandler

Event handlers should do all the necessary checks in this method (rather than in the constructor, or in process()) so that the caller, which is mostly executed in the ipc context can fail fast. Process is executed async from the client ipc, so this method gives a quick chance to do some basic checks. Should be called after constructing the EventHandler, and before process().

Overrides:

prepare in class EventHandler

Returns:

the instance of this class

Throws:

Exception - when something goes wrong

process

public void process()

Execute the core common portions of taking a snapshot. The snapshotRegions(List) call should get implemented for each snapshot flavor.

Specified by:

process in class EventHandler

completeSnapshot

public void completeSnapshot(org.apache.hadoop.fs.Path snapshotDir,
                             org.apache.hadoop.fs.Path workingDir,
                             org.apache.hadoop.fs.FileSystem fs)
                      throws SnapshotCreationException,
                             IOException

Reset the manager to allow another snapshot to proceed

Parameters:

snapshotDir - final path of the snapshot

workingDir - directory where the in progress snapshot was built

fs - FileSystem where the snapshot was built

Throws:

SnapshotCreationException - if the snapshot could not be moved

IOException - the filesystem could not be reached

downgradeToSharedTableLock

protected abstract boolean downgradeToSharedTableLock()

When taking snapshot, first we must acquire the exclusive table lock to confirm that there are no ongoing merge/split procedures. But later, we should try our best to release the exclusive lock as this may hurt the availability, because we need to hold the shared lock when assigning regions.

See HBASE-21480 for more details.

snapshotRegions

protected abstract void snapshotRegions(List<Pair<RegionInfo,ServerName>> regions)
                                 throws IOException,
                                        org.apache.zookeeper.KeeperException

Snapshot the specified regions

Throws:

IOException

org.apache.zookeeper.KeeperException

snapshotDisabledRegion

protected void snapshotDisabledRegion(RegionInfo regionInfo)
                               throws IOException

Take a snapshot of the specified disabled region

Throws:

IOException

cancel

public void cancel(String why)

Description copied from interface: SnapshotSentinel

Actively cancel a running snapshot.

Specified by:

cancel in interface SnapshotSentinel

Parameters:

why - Reason for cancellation.

isFinished

public boolean isFinished()

Description copied from interface: SnapshotSentinel

Check to see if the snapshot is finished, where finished may be success or failure.

Specified by:

isFinished in interface SnapshotSentinel

Returns:

false if the snapshot is still in progress, true if the snapshot has finished

getCompletionTimestamp

public long getCompletionTimestamp()

Specified by:

getCompletionTimestamp in interface SnapshotSentinel

Returns:

-1 if the snapshot is in progress, otherwise the completion timestamp.

getSnapshot

public SnapshotProtos.SnapshotDescription getSnapshot()

Specified by:

getSnapshot in interface SnapshotSentinel

Returns:

the description of the snapshot being run

getExceptionIfFailed

public ForeignException getExceptionIfFailed()

Description copied from interface: SnapshotSentinel

Get the exception that caused the snapshot to fail, if the snapshot has failed.

Specified by:

getExceptionIfFailed in interface SnapshotSentinel

Returns:

ForeignException that caused the snapshot to fail, or null if the snapshot is still in progress or has succeeded

rethrowExceptionIfFailed

public void rethrowExceptionIfFailed()
                              throws ForeignException

Description copied from interface: SnapshotSentinel

Rethrow the exception returned by SnapshotSentinel.getExceptionIfFailed(). If there is no exception this is a no-op.

Specified by:

rethrowExceptionIfFailed in interface SnapshotSentinel

Throws:

ForeignException - all exceptions from remote sources are procedure exceptions

rethrowException

public void rethrowException()
                      throws ForeignException

Description copied from interface: ForeignExceptionSnare

Rethrow an exception currently held by the ForeignExceptionSnare. If there is no exception this is a no-op

Specified by:

rethrowException in interface ForeignExceptionSnare

Throws:

ForeignException - all exceptions from remote sources are procedure exceptions

hasException

public boolean hasException()

Description copied from interface: ForeignExceptionSnare

Non-exceptional form of ForeignExceptionSnare.rethrowException(). Checks to see if any process to which the exception checkers is bound has created an error that would cause a failure.

Specified by:

hasException in interface ForeignExceptionSnare

Returns:

true if there has been an error,false otherwise

getException

public ForeignException getException()

Description copied from interface: ForeignExceptionSnare

Get the value of the captured exception.

Specified by:

getException in interface ForeignExceptionSnare

Returns:

the captured foreign exception or null if no exception captured.