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 the 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.
PinEvent	beginPin(boolean writeLock, long filePageId, PageSwapper swapper) A page is to be pinned.
void	mappedFile(File file) The given file has been mapped, where no existing mapping for that file existed.
void	unmappedFile(File file) The last reference to the given file has been unmapped.

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

bytesRead, bytesWritten, evictionExceptions, evictions, faults, filesMapped, filesUnmapped, flushes, 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.

beginPin

PinEvent beginPin(boolean writeLock,
                  long filePageId,
                  PageSwapper swapper)

A page is to be pinned.

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.