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

Class CacheReplicationMonitor

java.lang.Object

java.lang.Thread

org.apache.hadoop.util.concurrent.SubjectInheritingThread

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

All Implemented Interfaces:

Closeable, AutoCloseable, Runnable

@LimitedPrivate("HDFS")
public class CacheReplicationMonitor
extends org.apache.hadoop.util.concurrent.SubjectInheritingThread
implements 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

Thread.State, 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, ReentrantLock lock)

Method Summary

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

Methods inherited from class org.apache.hadoop.util.concurrent.SubjectInheritingThread

run, start

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, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Details

CacheReplicationMonitor

public CacheReplicationMonitor(FSNamesystem namesystem,
 CacheManager cacheManager,
 long intervalMs,
 ReentrantLock lock)

Method Details

work

public void work()

Overrides:

work in class org.apache.hadoop.util.concurrent.SubjectInheritingThread

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 IOException

Shut down the monitor thread.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException