Package org.apache.cassandra.io.util

Class FileHandle

java.lang.Object

org.apache.cassandra.utils.concurrent.SharedCloseableImpl

org.apache.cassandra.io.util.FileHandle

All Implemented Interfaces:

java.lang.AutoCloseable, SharedCloseable

public class FileHandle
extends SharedCloseableImpl

FileHandle provides access to a file for reading, including the ones written by various SequentialWriter instances, and it is typically used by SSTableReader.

Use FileHandle.Builder to create an instance, and call createReader() (and its variants) to access the readers for the underlying file.

You can use FileHandle.Builder.complete() several times during its lifecycle with different overrideLength(i.e. early opening file). For that reason, the builder keeps a reference to the file channel and makes a copy for each FileHandle.Builder.complete() call. Therefore, it is important to close the FileHandle.Builder when it is no longer needed, as well as any FileHandle instances.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	FileHandle.Builder	Configures how the file will be read (compressed, mmapped, use cache etc.)

Field Summary

Fields

Modifier and Type	Field	Description
ChannelProxy	channel
long	onDiskLength

Method Summary

Modifier and Type	Method	Description
void	addTo(Ref.IdentityCollection identities)
java.util.Optional<CompressionMetadata>	compressionMetadata()
RandomAccessReader	createReader()	Create RandomAccessReader with configured method of reading content of the file.
FileDataInput	createReader(long position)
RandomAccessReader	createReader(com.google.common.util.concurrent.RateLimiter limiter)	Create RandomAccessReader with configured method of reading content of the file.
long	dataLength()
void	dropPageCache(long before)	Drop page cache from start to given before.
File	file()
Rebufferer	instantiateRebufferer(com.google.common.util.concurrent.RateLimiter limiter)
java.lang.String	path()
RebuffererFactory	rebuffererFactory()
FileHandle	sharedCopy()
java.lang.String	toString()

Methods inherited from class org.apache.cassandra.utils.concurrent.SharedCloseableImpl

close, close, isCleanedUp

Methods inherited from class java.lang.Object

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

Field Detail

channel

public final ChannelProxy channel

onDiskLength

public final long onDiskLength

Method Detail

file

public File file()

Returns:

file this factory is referencing

path

public java.lang.String path()

dataLength

public long dataLength()

rebuffererFactory

public RebuffererFactory rebuffererFactory()

compressionMetadata

public java.util.Optional<CompressionMetadata> compressionMetadata()

addTo

public void addTo(Ref.IdentityCollection identities)

Specified by:

addTo in interface SharedCloseable

Overrides:

addTo in class SharedCloseableImpl

sharedCopy

public FileHandle sharedCopy()

Returns:

a new instance of the object representing the same state and backed by the same underlying resources. Coordinates with the original (and other instances) when the underlying resource should be closed. Throws an exception if the shared resource has already been closed.

createReader

public RandomAccessReader createReader()

Create RandomAccessReader with configured method of reading content of the file.

Returns:

RandomAccessReader for the file

createReader

public RandomAccessReader createReader(com.google.common.util.concurrent.RateLimiter limiter)

Create RandomAccessReader with configured method of reading content of the file. Reading from file will be rate limited by given RateLimiter.

Parameters:

limiter - RateLimiter to use for rate limiting read

Returns:

RandomAccessReader for the file

createReader

public FileDataInput createReader(long position)

dropPageCache

public void dropPageCache(long before)

Drop page cache from start to given before.

Parameters:

before - uncompressed position from start of the file to be dropped from cache. if 0, to end of file.

instantiateRebufferer

public Rebufferer instantiateRebufferer(com.google.common.util.concurrent.RateLimiter limiter)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object