Package com.orientechnologies.orient.core.storage.cache.chm

Class AsyncReadCache

java.lang.Object

com.orientechnologies.orient.core.storage.cache.chm.AsyncReadCache

All Implemented Interfaces:

OReadCache

public final class AsyncReadCache
extends Object
implements OReadCache

Disk cache based on ConcurrentHashMap and eviction policy which is asynchronously processed by handling set of events logged in lock free event buffer. This feature first was introduced in Caffeine framework https://github.com/ben-manes/caffeine and in ConcurrentLinkedHashMap library https://github.com/ben-manes/concurrentlinkedhashmap . The difference is that if consumption of memory in cache is bigger than 1% disk cache is switched from asynchronous processing of stream of events to synchronous processing. But that is true only for threads which cause loading of additional pages from write cache to disk cache. Window TinyLFU policy is used as cache eviction policy because it prevents usage of ghost entries and as result considerably decrease usage of heap memory.

Field Summary

Fields inherited from interface com.orientechnologies.orient.core.storage.cache.OReadCache

MIN_CACHE_SIZE

Constructor Summary

Constructors

Constructor	Description
AsyncReadCache(OByteBufferPool bufferPool, long maxCacheSizeInBytes, int pageSize, boolean trackHitRate)

Method Summary

Modifier and Type	Method	Description
final long	addFile(String fileName, long fileId, OWriteCache writeCache)
final long	addFile(String fileName, OWriteCache writeCache)
final OCacheEntry	allocateNewPage(long fileId, OWriteCache writeCache, OLogSequenceNumber startLSN)
final void	changeMaximumAmountOfMemory(long maxMemory)
final void	clear()
final void	closeFile(long fileId, boolean flush, OWriteCache writeCache)
final void	closeStorage(OWriteCache writeCache)	Closes all files inside of write cache and flushes all associated data.
final void	deleteFile(long fileId, OWriteCache writeCache)
final void	deleteStorage(OWriteCache writeCache)
final long	getUsedMemory()
final OCacheEntry	loadForRead(long fileId, long pageIndex, OWriteCache writeCache, boolean verifyChecksums)
final OCacheEntry	loadForWrite(long fileId, long pageIndex, OWriteCache writeCache, boolean verifyChecksums, OLogSequenceNumber startLSN)
final void	releaseFromRead(OCacheEntry cacheEntry)
final void	releaseFromWrite(OCacheEntry cacheEntry, OWriteCache writeCache, boolean changed)
final OCacheEntry	silentLoadForRead(long extFileId, int pageIndex, OWriteCache writeCache, boolean verifyChecksums)
final void	truncateFile(long fileId, OWriteCache writeCache)

Methods inherited from class java.lang.Object

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

Constructor Details

AsyncReadCache

public AsyncReadCache(OByteBufferPool bufferPool,
 long maxCacheSizeInBytes,
 int pageSize,
 boolean trackHitRate)

Method Details

addFile

public final long addFile(String fileName,
 OWriteCache writeCache)
                   throws IOException

Specified by:

addFile in interface OReadCache

Throws:

IOException

addFile

public final long addFile(String fileName,
 long fileId,
 OWriteCache writeCache)
                   throws IOException

Specified by:

addFile in interface OReadCache

Throws:

IOException

loadForWrite

public final OCacheEntry loadForWrite(long fileId,
 long pageIndex,
 OWriteCache writeCache,
 boolean verifyChecksums,
 OLogSequenceNumber startLSN)

Specified by:

loadForWrite in interface OReadCache

loadForRead

public final OCacheEntry loadForRead(long fileId,
 long pageIndex,
 OWriteCache writeCache,
 boolean verifyChecksums)

Specified by:

loadForRead in interface OReadCache

silentLoadForRead

public final OCacheEntry silentLoadForRead(long extFileId,
 int pageIndex,
 OWriteCache writeCache,
 boolean verifyChecksums)

Specified by:

silentLoadForRead in interface OReadCache

changeMaximumAmountOfMemory

public final void changeMaximumAmountOfMemory(long maxMemory)

Specified by:

changeMaximumAmountOfMemory in interface OReadCache

releaseFromRead

public final void releaseFromRead(OCacheEntry cacheEntry)

Specified by:

releaseFromRead in interface OReadCache

releaseFromWrite

public final void releaseFromWrite(OCacheEntry cacheEntry,
 OWriteCache writeCache,
 boolean changed)

Specified by:

releaseFromWrite in interface OReadCache

allocateNewPage

public final OCacheEntry allocateNewPage(long fileId,
 OWriteCache writeCache,
 OLogSequenceNumber startLSN)
                                  throws IOException

Specified by:

allocateNewPage in interface OReadCache

Throws:

IOException

getUsedMemory

public final long getUsedMemory()

Specified by:

getUsedMemory in interface OReadCache

clear

public final void clear()

Specified by:

clear in interface OReadCache

truncateFile

public final void truncateFile(long fileId,
 OWriteCache writeCache)
                        throws IOException

Specified by:

truncateFile in interface OReadCache

Throws:

IOException

closeFile

public final void closeFile(long fileId,
 boolean flush,
 OWriteCache writeCache)

Specified by:

closeFile in interface OReadCache

deleteFile

public final void deleteFile(long fileId,
 OWriteCache writeCache)
                      throws IOException

Specified by:

deleteFile in interface OReadCache

Throws:

IOException

deleteStorage

public final void deleteStorage(OWriteCache writeCache)
                         throws IOException

Specified by:

deleteStorage in interface OReadCache

Throws:

IOException

closeStorage

public final void closeStorage(OWriteCache writeCache)
                        throws IOException

Description copied from interface: OReadCache

Closes all files inside of write cache and flushes all associated data.

Specified by:

closeStorage in interface OReadCache

Parameters:

writeCache - Write cache to close.

Throws:

IOException