Package org.apache.hadoop.hdfs.shortcircuit

Class DfsClientShmManager

java.lang.Object

org.apache.hadoop.hdfs.shortcircuit.DfsClientShmManager

All Implemented Interfaces:

Closeable, AutoCloseable

@Private
public class DfsClientShmManager
extends Object
implements Closeable

Manages short-circuit memory segments for an HDFS client. Clients are responsible for requesting and releasing shared memory segments used for communicating with the DataNode. The client will try to allocate new slots in the set of existing segments, falling back to getting a new segment from the DataNode via DataTransferProtocol.requestShortCircuitFds(org.apache.hadoop.hdfs.protocol.ExtendedBlock, org.apache.hadoop.security.token.Token<org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier>, org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.SlotId, int, boolean). The counterpart to this class on the DataNode is ShortCircuitRegistry. See ShortCircuitRegistry for more information on the communication protocol.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	DfsClientShmManager.PerDatanodeVisitorInfo
static interface	DfsClientShmManager.Visitor

Method Summary

Modifier and Type	Method	Description
ShortCircuitShm.Slot	allocSlot(DatanodeInfo datanode, DomainPeer peer, org.apache.commons.lang3.mutable.MutableBoolean usedPeer, ExtendedBlockId blockId, String clientName)
void	close()	Close the DfsClientShmManager.
void	freeSlot(ShortCircuitShm.Slot slot)
org.apache.hadoop.net.unix.DomainSocketWatcher	getDomainSocketWatcher()
int	getShmNum()
String	toString()
void	visit(DfsClientShmManager.Visitor visitor)

Methods inherited from class java.lang.Object

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

Method Details

allocSlot

public ShortCircuitShm.Slot allocSlot(DatanodeInfo datanode,
 DomainPeer peer,
 org.apache.commons.lang3.mutable.MutableBoolean usedPeer,
 ExtendedBlockId blockId,
 String clientName)
                               throws IOException

Throws:

IOException

freeSlot

public void freeSlot(ShortCircuitShm.Slot slot)

visit

@VisibleForTesting
public void visit(DfsClientShmManager.Visitor visitor)
           throws IOException

Throws:

IOException

close

public void close()
           throws IOException

Close the DfsClientShmManager.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

getDomainSocketWatcher

@VisibleForTesting
public org.apache.hadoop.net.unix.DomainSocketWatcher getDomainSocketWatcher()

getShmNum

@VisibleForTesting
public int getShmNum()