com.bigdata.io.writecache

Class WriteCacheCounters

java.lang.Object

com.bigdata.io.writecache.WriteCacheCounters

All Implemented Interfaces:

IWriteCacheCounters

Direct Known Subclasses:

WriteCacheServiceCounters

public class WriteCacheCounters
extends Object
implements IWriteCacheCounters

Performance counters for the WriteCache.

Note: thread-safety is required for: nhit and nmiss. The rest should be Ok without additional synchronization, CAS operators, etc (mainly because they are updated while holding a lock).

Author:

Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
long	bytesAccepted #of bytes accepted for eventual write onto the backing channel.
long	bytesWritten #of bytes written onto the backing channel.
long	elapsedWriteNanos Total elapsed time writing onto the backing channel.
long	naccept #of records accepted for eventual write onto the backing channel.
long	nchannelWrite #of writes on the backing channel.
CAT	nhit #of read requests that are satisfied by the write cache.
CAT	nmiss The #of read requests that are not satisfied by the write cache.

Fields inherited from interface com.bigdata.io.writecache.IWriteCacheCounters

BYTES_ACCEPTED, BYTES_PER_WRITE, BYTES_WRITTEN, HIT_RATE, NACCEPT, NCHANNEL_WRITE, NHIT, NMISS, WRITE_SECS

Constructor Summary

Constructors

Constructor and Description
WriteCacheCounters()

Method Summary

Methods

Modifier and Type	Method and Description
CounterSet	getCounters()
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

nhit

public final CAT nhit

#of read requests that are satisfied by the write cache.

nmiss

public final CAT nmiss

The #of read requests that are not satisfied by the write cache.

naccept

public long naccept

#of records accepted for eventual write onto the backing channel.

bytesAccepted

public long bytesAccepted

#of bytes accepted for eventual write onto the backing channel.

nchannelWrite

public long nchannelWrite

#of writes on the backing channel. Note that some write cache implementations do ordered writes and will therefore do one write per record while others do append only and therefore do one write per write cache flush. Note that in both cases we may have to redo a write if the backing channel was concurrently closed, so the value here can diverge from the #of accepted records and the #of requested flushes.

bytesWritten

public long bytesWritten

#of bytes written onto the backing channel.

elapsedWriteNanos

public long elapsedWriteNanos

Total elapsed time writing onto the backing channel.

Constructor Detail

WriteCacheCounters

public WriteCacheCounters()

Method Detail

getCounters

public CounterSet getCounters()

toString

public String toString()

Overrides:

toString in class Object