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

Class LeaseManager

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.LeaseManager

@Private
public class LeaseManager
extends java.lang.Object

LeaseManager does the lease housekeeping for writing on files. This class also provides useful static methods for lease recovery. Lease Recovery Algorithm 1) Namenode retrieves lease information 2) For each file f in the lease, consider the last block b of f 2.1) Get the datanodes which contains b 2.2) Assign one of the datanodes as the primary datanode p 2.3) p obtains a new generation stamp from the namenode 2.4) p gets the block info from each datanode 2.5) p computes the minimum block length 2.6) p updates the datanodes, which have a valid generation stamp, with the new generation stamp and the minimum block length 2.7) p acknowledges the namenode the update results 2.8) Namenode updates the BlockInfo 2.9) Namenode removes f from the lease and removes the lease once all files have been removed 2.10) Namenode commit changes to edit log

Field Summary

Fields

Modifier and Type	Field	Description
static org.slf4j.Logger	LOG

Method Summary

Modifier and Type	Method	Description
int	countLease()
java.util.Set<INodesInPath>	getINodeWithLeases(INodeDirectory ancestorDir)	Get INodesInPath for all files under the ancestor directory which has valid lease.
org.apache.hadoop.hdfs.server.namenode.LeaseManager.Lease	getLease(INodeFile src)
org.apache.hadoop.fs.BatchedRemoteIterator.BatchedListEntries<org.apache.hadoop.hdfs.protocol.OpenFileEntry>	getUnderConstructionFiles(long prevId)
org.apache.hadoop.fs.BatchedRemoteIterator.BatchedListEntries<org.apache.hadoop.hdfs.protocol.OpenFileEntry>	getUnderConstructionFiles(long prevId, java.lang.String path)	Get a batch of under construction files from the currently active leases.
void	runLeaseChecks()
void	setLeasePeriod(long softLimit, long hardLimit)
java.lang.String	toString()
void	triggerMonitorCheckNow()	Trigger the currently-running Lease monitor to re-check its leases immediately.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

public static final org.slf4j.Logger LOG

Method Detail

getINodeWithLeases

public java.util.Set<INodesInPath> getINodeWithLeases(INodeDirectory ancestorDir)
                                               throws java.io.IOException

Get INodesInPath for all files under the ancestor directory which has valid lease. If the ancestor directory is null, then return all files in the system with valid lease. Callers must hold FSNamesystem read or write lock.

Parameters:

ancestorDir - the ancestor INodeDirectory

Returns:

Set<INodesInPath>

Throws:

java.io.IOException

getUnderConstructionFiles

public org.apache.hadoop.fs.BatchedRemoteIterator.BatchedListEntries<org.apache.hadoop.hdfs.protocol.OpenFileEntry> getUnderConstructionFiles(long prevId)
                                                                                                                                       throws java.io.IOException

Throws:

java.io.IOException

getUnderConstructionFiles

public org.apache.hadoop.fs.BatchedRemoteIterator.BatchedListEntries<org.apache.hadoop.hdfs.protocol.OpenFileEntry> getUnderConstructionFiles(long prevId,
                                                                                                                                              java.lang.String path)
                                                                                                                                       throws java.io.IOException

Get a batch of under construction files from the currently active leases. File INodeID is the cursor used to fetch new batch of results and the batch size is configurable using below config param. Since the list is fetched in batches, it does not represent a consistent view of all open files.

Parameters:

prevId - the INodeID cursor

Throws:

java.io.IOException

See Also:

DFSConfigKeys.DFS_NAMENODE_LIST_OPENFILES_NUM_RESPONSES

getLease

public org.apache.hadoop.hdfs.server.namenode.LeaseManager.Lease getLease(INodeFile src)

Returns:

the lease containing src

countLease

@VisibleForTesting
public int countLease()

Returns:

the number of leases currently in the system

setLeasePeriod

public void setLeasePeriod(long softLimit,
                           long hardLimit)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

triggerMonitorCheckNow

@VisibleForTesting
public void triggerMonitorCheckNow()

Trigger the currently-running Lease monitor to re-check its leases immediately. This is for use by unit tests.

runLeaseChecks

@VisibleForTesting
public void runLeaseChecks()