org.neo4j.io.pagecache.tracing

Interface PageCacheTracer

All Superinterfaces:

PageCacheCounters

All Known Implementing Classes:

DefaultPageCacheTracer

public interface PageCacheTracer
extends PageCacheCounters

A PageCacheTracer receives a steady stream of events and data about what whole page cache is doing. Implementations of this interface should be as efficient as possible, lest they severely slow down the page cache.

Field Summary

Fields

Modifier and Type	Field and Description
static PageCacheTracer	NULL A PageCacheTracer that does nothing other than return the NULL variants of the companion interfaces.

Method Summary

Modifier and Type	Method and Description
MajorFlushEvent	beginCacheFlush() The PageCache wants to flush all its bound pages.
MajorFlushEvent	beginFileFlush(PageSwapper swapper) A PagedFile wants to flush all its bound pages.
EvictionRunEvent	beginPageEvictions(int pageCountToEvict) A background eviction has begun.
void	bytesRead(long bytesRead) Report number of bytes read
void	bytesWritten(long bytesWritten) Report number of bytes written
void	evictionExceptions(long evictionExceptions) Report number of eviction exceptions
void	evictions(long evictions) Report number of observed evictions
void	faults(long faults) Report number of observed faults
void	flushes(long flushes) Report number of flushes
void	hits(long hits) Report number of observer hits
void	mappedFile(File file) The given file has been mapped, where no existing mapping for that file existed.
void	pins(long pins) Report number of observed pins
void	unmappedFile(File file) The last reference to the given file has been unmapped.
void	unpins(long unpins) Report number of observed unpins

Methods inherited from interface org.neo4j.io.pagecache.monitoring.PageCacheCounters

bytesRead, bytesWritten, evictionExceptions, evictions, faults, filesMapped, filesUnmapped, flushes, hitRatio, hits, pins, unpins

Field Detail

NULL

static final PageCacheTracer NULL

A PageCacheTracer that does nothing other than return the NULL variants of the companion interfaces.

Method Detail

mappedFile

void mappedFile(File file)

The given file has been mapped, where no existing mapping for that file existed.

unmappedFile

void unmappedFile(File file)

The last reference to the given file has been unmapped.

beginPageEvictions

EvictionRunEvent beginPageEvictions(int pageCountToEvict)

A background eviction has begun. Called from the background eviction thread. This call will be paired with a following PageCacheTracer#endPageEviction call. The method returns an EvictionRunEvent to represent the event of this eviction run.

beginFileFlush

MajorFlushEvent beginFileFlush(PageSwapper swapper)

A PagedFile wants to flush all its bound pages.

beginCacheFlush

MajorFlushEvent beginCacheFlush()

The PageCache wants to flush all its bound pages.

pins

void pins(long pins)

Report number of observed pins

Parameters:

pins - number of pins

unpins

void unpins(long unpins)

Report number of observed unpins

Parameters:

unpins - number of unpins

hits

void hits(long hits)

Report number of observer hits

Parameters:

hits - number of hits

faults

void faults(long faults)

Report number of observed faults

Parameters:

faults - number of faults

bytesRead

void bytesRead(long bytesRead)

Report number of bytes read

Parameters:

bytesRead - number of read bytes

evictions

void evictions(long evictions)

Report number of observed evictions

Parameters:

evictions - number of evictions

evictionExceptions

void evictionExceptions(long evictionExceptions)

Report number of eviction exceptions

Parameters:

evictionExceptions - number of eviction exceptions

bytesWritten

void bytesWritten(long bytesWritten)

Report number of bytes written

Parameters:

bytesWritten - number of written bytes

flushes

void flushes(long flushes)

Report number of flushes

Parameters:

flushes - number of flushes