Package 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<EventHandler>, Runnable, ForeignExceptionSnare, SnapshotSentinel

Direct Known Subclasses:

DisabledTableSnapshotHandler, EnabledTableSnapshotHandler

@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	Description
protected final org.apache.hadoop.conf.Configuration	conf
private boolean	finished
static final String	HBASE_SNAPSHOT_MASTER_LOCK_ACQUIRE_TIMEOUT
protected TableDescriptor	htd
private final long	lockAcquireTimeoutMs	Snapshot creation requires table lock.
private static final org.slf4j.Logger	LOG
protected final MasterServices	master
protected final MetricsSnapshot	metricsSnapshot
protected final ForeignExceptionDispatcher	monitor
protected final org.apache.hadoop.fs.Path	rootDir
protected final org.apache.hadoop.fs.FileSystem	rootFs
protected final org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription	snapshot
private final org.apache.hadoop.fs.Path	snapshotDir
protected final SnapshotManager	snapshotManager
protected final SnapshotManifest	snapshotManifest
protected final TableName	snapshotTable
protected final MonitoredTask	status
private final LockManager.MasterLock	tableLock
private final MasterSnapshotVerifier	verifier
protected final org.apache.hadoop.fs.Path	workingDir
protected final org.apache.hadoop.fs.FileSystem	workingDirFs

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

eventType, seqids, server, waitingTimeForEvents

Constructor Summary

Constructors

Constructor	Description
TakeSnapshotHandler(org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription snapshot, MasterServices masterServices, SnapshotManager snapshotManager)

Method Summary

Modifier and Type	Method	Description
void	cancel(String why)	Actively cancel a running snapshot.
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()	Returns -1 if the snapshot is in progress, otherwise the completion timestamp.
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.
org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription	getSnapshot()	Returns the description of the snapshot being run
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.
private TableDescriptor	loadTableDescriptor()
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 Details

LOG

private static final org.slf4j.Logger LOG

HBASE_SNAPSHOT_MASTER_LOCK_ACQUIRE_TIMEOUT

public static final String HBASE_SNAPSHOT_MASTER_LOCK_ACQUIRE_TIMEOUT

See Also:

• Constant Field Values

finished

private volatile boolean finished

master

protected final MasterServices master

metricsSnapshot

protected final MetricsSnapshot metricsSnapshot

snapshot

protected final org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription snapshot

conf

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

rootFs

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

workingDirFs

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

rootDir

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

snapshotDir

private final org.apache.hadoop.fs.Path snapshotDir

workingDir

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

verifier

private final MasterSnapshotVerifier verifier

monitor

protected final ForeignExceptionDispatcher monitor

tableLock

private final LockManager.MasterLock tableLock

status

protected final MonitoredTask status

snapshotTable

protected final TableName snapshotTable

snapshotManifest

protected final SnapshotManifest snapshotManifest

snapshotManager

protected final SnapshotManager snapshotManager

lockAcquireTimeoutMs

private final long lockAcquireTimeoutMs

Snapshot creation requires table lock. If any region of the table is in transition, table lock cannot be acquired by LockProcedure and hence snapshot creation could hang for potentially very long time. This timeout will ensure snapshot creation fails-fast by waiting for only given timeout.

htd

protected TableDescriptor htd

Constructor Details

TakeSnapshotHandler

public TakeSnapshotHandler(org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription snapshot,
 MasterServices masterServices,
 SnapshotManager snapshotManager)
                    throws IOException

Parameters:

snapshot - descriptor of the snapshot to take

masterServices - master services provider

Throws:

IllegalArgumentException - if the working snapshot directory set from the configuration is the same as the completed snapshot directory

IOException - if the file system of the working snapshot directory cannot be determined

Method Details

loadTableDescriptor

private TableDescriptor loadTableDescriptor()
                                     throws IOException

Throws:

IOException

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

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()

Description copied from interface: SnapshotSentinel

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

Specified by:

getCompletionTimestamp in interface SnapshotSentinel

getSnapshot

public org.apache.hadoop.hbase.shaded.protobuf.generated.SnapshotProtos.SnapshotDescription getSnapshot()

Description copied from interface: SnapshotSentinel

Returns the description of the snapshot being run

Specified by:

getSnapshot in interface SnapshotSentinel

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 all exceptions from remote sources are procedure exceptions

Specified by:

rethrowException in interface ForeignExceptionSnare

Throws:

ForeignException

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.