Package org.apache.iceberg.io

Class ContentCache

java.lang.Object

org.apache.iceberg.io.ContentCache

public class ContentCache
extends Object

Class that provides file-content caching during reading.

The file-content caching is initiated by calling tryCache(InputFile). Given a FileIO, a file location string, and file length that is within allowed limit, ContentCache will return a ContentCache.CachingInputFile that is backed by the cache. Calling InputFile.newStream() will return a ByteBufferInputStream backed by list of ByteBuffer from the cache if such file-content exist in the cache. If the file-content does not exist in the cache yet, a regular InputFile will be instantiated, read-ahead, and loaded into the cache before returning ByteBufferInputStream. The regular InputFile is also used as a fallback if cache loading fail.

Constructor Summary

Constructors

Constructor	Description
ContentCache(long expireAfterAccessMs, long maxTotalBytes, long maxContentLength)	Constructor for ContentCache class.

Method Summary

Modifier and Type	Method	Description
void	cleanUp()
long	estimatedCacheSize()
long	expireAfterAccess()
void	invalidate(String key)	Invalidate the cache entry for the given key.
void	invalidateAll()	Deprecated. since 1.7.0, will be removed in 2.0.0; This method does only best-effort invalidation and is susceptible to a race condition.
long	maxContentLength()
long	maxTotalBytes()
com.github.benmanes.caffeine.cache.stats.CacheStats	stats()
String	toString()
InputFile	tryCache(InputFile input)	Try cache the file-content of file in the given location upon stream reading.

Methods inherited from class java.lang.Object

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

Constructor Details

ContentCache

public ContentCache(long expireAfterAccessMs,
 long maxTotalBytes,
 long maxContentLength)

Constructor for ContentCache class.

Parameters:

expireAfterAccessMs - controls the duration for which entries in the ContentCache are hold since last access. Must be greater or equal than 0. Setting 0 means cache entries expire only if it gets evicted due to memory pressure.

maxTotalBytes - controls the maximum total amount of bytes to cache in ContentCache. Must be greater than 0.

maxContentLength - controls the maximum length of file to be considered for caching. Must be greater than 0.

Method Details

expireAfterAccess

public long expireAfterAccess()

maxContentLength

public long maxContentLength()

maxTotalBytes

public long maxTotalBytes()

stats

public com.github.benmanes.caffeine.cache.stats.CacheStats stats()

tryCache

public InputFile tryCache(InputFile input)

Try cache the file-content of file in the given location upon stream reading.

If length is longer than maximum length allowed by ContentCache, a regular InputFile and no caching will be done for that file. Otherwise, this method will return a ContentCache.CachingInputFile that serve file reads backed by ContentCache.

Parameters:

input - an InputFile to cache

Returns:

a ContentCache.CachingInputFile if length is within allowed limit. Otherwise, a regular InputFile for given location.

invalidate

public void invalidate(String key)

Invalidate the cache entry for the given key.

Note: if there is ongoing load, this is a blocking operation, i.e. it will wait for the load to complete before invalidating the entry.

invalidateAll

@Deprecated
public void invalidateAll()

Deprecated.

since 1.7.0, will be removed in 2.0.0; This method does only best-effort invalidation and is susceptible to a race condition. If the caller changed the state that could be cached (perhaps files on the storage) and calls this method, there is no guarantee that the cache will not contain stale entries some time after this method returns.

cleanUp

public void cleanUp()

estimatedCacheSize

public long estimatedCacheSize()

toString

public String toString()

Overrides:

toString in class Object