Package org.apache.hadoop.hdfs.server.blockmanagement

Class CacheReplicationMonitor

java.lang.Object

java.lang.Thread

org.apache.hadoop.hdfs.server.blockmanagement.CacheReplicationMonitor

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.lang.Runnable

@LimitedPrivate("HDFS")
public class CacheReplicationMonitor
extends java.lang.Thread
implements java.io.Closeable

Scans the namesystem, scheduling blocks to be cached as appropriate. The CacheReplicationMonitor does a full scan when the NameNode first starts up, and at configurable intervals afterwards.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor	Description
CacheReplicationMonitor(FSNamesystem namesystem, CacheManager cacheManager, long intervalMs, java.util.concurrent.locks.ReentrantLock lock)

Method Summary

Modifier and Type	Method	Description
void	close()	Shut down the monitor thread.
void	run()
void	setNeedsRescan()	Indicates to the CacheReplicationMonitor that there have been CacheManager changes that require a rescan.
void	waitForRescanIfNeeded()	Waits for a rescan to complete.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, onSpinWait, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheReplicationMonitor

public CacheReplicationMonitor(FSNamesystem namesystem,
                               CacheManager cacheManager,
                               long intervalMs,
                               java.util.concurrent.locks.ReentrantLock lock)

Method Detail

run

public void run()

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

waitForRescanIfNeeded

public void waitForRescanIfNeeded()

Waits for a rescan to complete. This doesn't guarantee consistency with pending operations, only relative recency, since it will not force a new rescan if a rescan is already underway.

Note that this call will release the FSN lock, so operations before and after are not atomic.

setNeedsRescan

public void setNeedsRescan()

Indicates to the CacheReplicationMonitor that there have been CacheManager changes that require a rescan.

close

public void close()
           throws java.io.IOException

Shut down the monitor thread.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException