Package org.apache.hadoop.hdfs.server.datanode

Class DiskBalancer.DiskBalancerMover

java.lang.Object

org.apache.hadoop.hdfs.server.datanode.DiskBalancer.DiskBalancerMover

All Implemented Interfaces:

DiskBalancer.BlockMover

Enclosing class:

DiskBalancer

public static class DiskBalancer.DiskBalancerMover
extends java.lang.Object
implements DiskBalancer.BlockMover

Actual DataMover class for DiskBalancer.

Constructor Summary

Constructors

Constructor	Description
DiskBalancerMover(FsDatasetSpi dataset, org.apache.hadoop.conf.Configuration conf)	Constructs diskBalancerMover.

Method Summary

Modifier and Type	Method	Description
long	computeDelay(long bytesCopied, long timeUsed, org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkItem item)	Computes sleep delay needed based on the block that just got copied.
void	copyBlocks(DiskBalancer.VolumePair pair, org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkItem item)	Copies blocks from a set of volumes.
FsDatasetSpi	getDataset()	Returns a pointer to the current dataset we are operating against.
long	getElapsedSeconds()	Number of seconds elapsed.
long	getStartTime()	Returns time when this plan started executing.
void	setExitFlag()	Signals copy block to exit.
void	setRunnable()	Sets Diskmover copyblocks into runnable state.
boolean	shouldRun()	Returns the shouldRun boolean flag.

Methods inherited from class java.lang.Object

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

Constructor Detail

DiskBalancerMover

public DiskBalancerMover(FsDatasetSpi dataset,
                         org.apache.hadoop.conf.Configuration conf)

Constructs diskBalancerMover.

Parameters:

dataset - Dataset

conf - Configuration

Method Detail

setRunnable

public void setRunnable()

Sets Diskmover copyblocks into runnable state.

Specified by:

setRunnable in interface DiskBalancer.BlockMover

setExitFlag

public void setExitFlag()

Signals copy block to exit.

Specified by:

setExitFlag in interface DiskBalancer.BlockMover

shouldRun

public boolean shouldRun()

Returns the shouldRun boolean flag.

computeDelay

@VisibleForTesting
public long computeDelay(long bytesCopied,
                         long timeUsed,
                         org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkItem item)

Computes sleep delay needed based on the block that just got copied. we copy using a burst mode, that is we let the copy proceed in full throttle. Once a copy is done, we compute how many bytes have been transferred and try to average it over the user specified bandwidth. In other words, This code implements a poor man's token bucket algorithm for traffic shaping.

Parameters:

bytesCopied - - byteCopied.

timeUsed - in milliseconds

item - DiskBalancerWorkItem

Returns:

sleep delay in Milliseconds.

copyBlocks

public void copyBlocks(DiskBalancer.VolumePair pair,
                       org.apache.hadoop.hdfs.server.datanode.DiskBalancerWorkItem item)

Copies blocks from a set of volumes.

Specified by:

copyBlocks in interface DiskBalancer.BlockMover

Parameters:

pair - - Source and Destination Volumes.

item - - Number of bytes to move from volumes.

getDataset

public FsDatasetSpi getDataset()

Returns a pointer to the current dataset we are operating against.

Specified by:

getDataset in interface DiskBalancer.BlockMover

Returns:

FsDatasetSpi

getStartTime

public long getStartTime()

Returns time when this plan started executing.

Specified by:

getStartTime in interface DiskBalancer.BlockMover

Returns:

Start time in milliseconds.

getElapsedSeconds

public long getElapsedSeconds()

Number of seconds elapsed.

Specified by:

getElapsedSeconds in interface DiskBalancer.BlockMover

Returns:

time in seconds