alluxio.client.file.cache

Class LocalCacheManager

java.lang.Object

alluxio.client.file.cache.LocalCacheManager

All Implemented Interfaces:

CacheManager, AutoCloseable

@ThreadSafe
public class LocalCacheManager
extends Object
implements CacheManager

A class to manage & serve cached pages. This class coordinates various components to respond for thread-safety and enforce cache replacement policies. The idea of creating a client-side cache is followed after "Improving In-Memory File System Reading Performance by Fine-Grained User-Space Cache Mechanisms" by Gu et al, which illustrates performance benefits for various read workloads. This class also introduces paging as a caching unit. Lock hierarchy in this class: All operations must follow this order to operate on pages:

1. Acquire corresponding page lock
2. Acquire metastore lock mMetaLock
3. Update metastore
4. Release metastore lock mMetaLock
5. Update the pagestore and evictor
6. Release corresponding page lock

Nested Class Summary

Nested classes/interfaces inherited from interface alluxio.client.file.cache.CacheManager

CacheManager.Factory, CacheManager.State

Method Summary

Modifier and Type	Method and Description
boolean	append(PageId pageId, int appendAt, byte[] page, CacheContext cacheContext)
void	close()
static LocalCacheManager	create(AlluxioConfiguration conf, PageMetaStore pageMetaStore)
boolean	delete(PageId pageId) Deletes a page from the cache.
int	get(PageId pageId, int pageOffset, int bytesToRead, byte[] buffer, int offsetInBuffer, CacheContext cacheContext) Reads a part of a page if the queried page is found in the cache, stores the result in buffer.
List<PageId>	getCachedPageIdsByFileId(String fileId, long fileLength) Get page ids by the given file id.
boolean	put(PageId pageId, byte[] page, CacheContext cacheContext) Puts a page into the cache manager with scope and quota respected.
CacheManager.State	state()

Methods inherited from class java.lang.Object

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

Methods inherited from interface alluxio.client.file.cache.CacheManager

get, get, put

Method Detail

create

public static LocalCacheManager create(AlluxioConfiguration conf,
                                       PageMetaStore pageMetaStore)
                                throws IOException

Parameters:

conf - the Alluxio configuration

pageMetaStore - the metadata store for local cache

Returns:

an instance of LocalCacheManager

Throws:

IOException

put

public boolean put(PageId pageId,
                   byte[] page,
                   CacheContext cacheContext)

Description copied from interface: CacheManager

Puts a page into the cache manager with scope and quota respected. This method is best effort. It is possible that this put operation returns without page written.

Specified by:

put in interface CacheManager

Parameters:

pageId - page identifier

page - page data

cacheContext - cache related context

Returns:

true if the put was successful, false otherwise

get

public int get(PageId pageId,
               int pageOffset,
               int bytesToRead,
               byte[] buffer,
               int offsetInBuffer,
               CacheContext cacheContext)

Description copied from interface: CacheManager

Reads a part of a page if the queried page is found in the cache, stores the result in buffer.

Specified by:

get in interface CacheManager

Parameters:

pageId - page identifier

pageOffset - offset into the page

bytesToRead - number of bytes to read in this page

buffer - destination buffer to write

offsetInBuffer - offset in the destination buffer to write

cacheContext - cache related context

Returns:

number of bytes read, 0 if page is not found, -1 on errors

delete

public boolean delete(PageId pageId)

Description copied from interface: CacheManager

Deletes a page from the cache.

Specified by:

delete in interface CacheManager

Parameters:

pageId - page identifier

Returns:

true if the page is successfully deleted, false otherwise

state

public CacheManager.State state()

Specified by:

state in interface CacheManager

Returns:

state of this cache

append

public boolean append(PageId pageId,
                      int appendAt,
                      byte[] page,
                      CacheContext cacheContext)

Specified by:

append in interface CacheManager

Returns:

true if append was successful

getCachedPageIdsByFileId

public List<PageId> getCachedPageIdsByFileId(String fileId,
                                             long fileLength)

Description copied from interface: CacheManager

Get page ids by the given file id.

Specified by:

getCachedPageIdsByFileId in interface CacheManager

Parameters:

fileId - file identifier

fileLength - file length (this will not be needed after we have per-file metadata)

Returns:

a list of page ids which belongs to the file

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Throws:

Exception