Package org.apache.hadoop.hdfs.server.namenode.ha

Class EditLogTailer

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.ha.EditLogTailer

@Private
@Evolving
public class EditLogTailer
extends Object

EditLogTailer represents a thread which periodically reads from edits journals and applies the transactions contained within to a given FSNamesystem.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_DEFAULT
static final String	DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_KEY	StandbyNode will hold namesystem lock to apply at most this many journal transactions.
static final org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor	Description
EditLogTailer(FSNamesystem namesystem, org.apache.hadoop.conf.Configuration conf)

Method Summary

Modifier and Type	Method	Description
void	catchupDuringFailover()
long	doTailEdits()
NamenodeProtocol	getCachedActiveProxy()
RemoteNameNodeInfo	getCurrentNN()
long	getLastLoadTimeMs()
long	getLastRollTimeMs()
void	setEditLog(FSEditLog editLog)
void	setShouldRunForTest(boolean shouldRun)
void	start()
void	stop()

Methods inherited from class java.lang.Object

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

Field Details

LOG

public static final org.slf4j.Logger LOG

DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_KEY

public static final String DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_KEY

StandbyNode will hold namesystem lock to apply at most this many journal transactions. It will then release the lock and re-acquire it to load more transactions. By default the write lock is held for the entire journal segment. Fine-grained locking allows read requests to get through.

See Also:

• Constant Field Values

DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_DEFAULT

public static final long DFS_HA_TAILEDITS_MAX_TXNS_PER_LOCK_DEFAULT

See Also:

• Constant Field Values

Constructor Details

EditLogTailer

public EditLogTailer(FSNamesystem namesystem,
 org.apache.hadoop.conf.Configuration conf)

Method Details

start

public void start()

stop

public void stop()
          throws IOException

Throws:

IOException

setEditLog

@VisibleForTesting
public void setEditLog(FSEditLog editLog)

catchupDuringFailover

public void catchupDuringFailover()
                           throws IOException

Throws:

IOException

doTailEdits

@VisibleForTesting
public long doTailEdits()
                 throws IOException,
InterruptedException

Throws:

IOException

InterruptedException

getLastLoadTimeMs

public long getLastLoadTimeMs()

Returns:

time in msec of when we last loaded a non-zero number of edits.

getCachedActiveProxy

@VisibleForTesting
public NamenodeProtocol getCachedActiveProxy()

getLastRollTimeMs

@VisibleForTesting
public long getLastRollTimeMs()

getCurrentNN

@VisibleForTesting
public RemoteNameNodeInfo getCurrentNN()

setShouldRunForTest

@VisibleForTesting
public void setShouldRunForTest(boolean shouldRun)