alluxio.worker.block

Class UfsIOManager

java.lang.Object

alluxio.worker.block.UfsIOManager

All Implemented Interfaces:

Closeable, AutoCloseable

public class UfsIOManager
extends Object
implements Closeable

Control UFS IO.

Constructor Summary

Constructors

Constructor and Description
UfsIOManager(UfsManager.UfsClient ufsClient)

Method Summary

Modifier and Type	Method and Description
void	close() Close.
double	getUsedThroughput(com.codahale.metrics.Meter meter) Get used throughput.
CompletableFuture<byte[]>	read(long blockId, long offset, long length, String ufsPath, boolean positionShort, String tag) Read from ufs.
void	setQuota(String tag, long throughput) Set throughput quota for tag.
void	start() Start schedule thread.

Methods inherited from class java.lang.Object

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

Constructor Detail

UfsIOManager

public UfsIOManager(UfsManager.UfsClient ufsClient)

Parameters:

ufsClient - ufs client

Method Detail

start

public void start()

Start schedule thread. Main reason is for test

close

public void close()

Close.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

setQuota

public void setQuota(String tag,
                     long throughput)

Set throughput quota for tag.

Parameters:

tag - the client name or tag

throughput - throughput limit in bytes

getUsedThroughput

public double getUsedThroughput(com.codahale.metrics.Meter meter)

Get used throughput.

Parameters:

meter - throughput meter

Returns:

throughput

read

public CompletableFuture<byte[]> read(long blockId,
                                      long offset,
                                      long length,
                                      String ufsPath,
                                      boolean positionShort,
                                      String tag)
                               throws ResourceExhaustedException

Read from ufs.

Parameters:

blockId - block id

offset - offset in ufs file

length - length to read

ufsPath - ufs path

positionShort - is position short or not, used for HDFS performance optimization. When the client buffer size is large ( > 2MB) and reads are guaranteed to be somewhat sequential, the `pread` API to HDFS is not as efficient as simple `read`. We introduce a heuristic to choose which API to use.

tag - user/client name or specific identifier of the read task

Returns:

content read

Throws:

ResourceExhaustedException - when too many read task happens