Package org.apache.lucene.store

Enum Class ReadAdvice

java.lang.Object

java.lang.Enum<ReadAdvice>

org.apache.lucene.store.ReadAdvice

All Implemented Interfaces:

Serializable, Comparable<ReadAdvice>, Constable

public enum ReadAdvice
extends Enum<ReadAdvice>

Advice regarding the read access pattern.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Enum

Enum.EnumDesc<E extends Enum<E>>

Enum Constant Summary

Enum Constants

Enum Constant	Description
NORMAL	Normal behavior.
RANDOM	Data is expected to be read in a random-access fashion, either by seeking often and reading relatively short sequences of bytes at once, or by reading data through the RandomAccessInput abstraction in random order.
RANDOM_PRELOAD	Data is treated as random-access memory in practice.
SEQUENTIAL	Data is expected to be read sequentially with very little seeking at most.

Method Summary

Modifier and Type	Method	Description
static ReadAdvice	valueOf(String name)	Returns the enum constant of this class with the specified name.
static ReadAdvice[]	values()	Returns an array containing the constants of this enum class, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Details

NORMAL

public static final ReadAdvice NORMAL

Normal behavior. Data is expected to be read mostly sequentially. The system is expected to cache the hottest pages.

RANDOM

public static final ReadAdvice RANDOM

Data is expected to be read in a random-access fashion, either by seeking often and reading relatively short sequences of bytes at once, or by reading data through the RandomAccessInput abstraction in random order.

SEQUENTIAL

public static final ReadAdvice SEQUENTIAL

Data is expected to be read sequentially with very little seeking at most. The system may read ahead aggressively and free pages soon after they are accessed.

RANDOM_PRELOAD

public static final ReadAdvice RANDOM_PRELOAD

Data is treated as random-access memory in practice. Directory implementations may explicitly load the content of the file in memory, or provide hints to the system so that it loads the content of the file into the page cache at open time. This should only be used on very small files that can be expected to fit in RAM with very high confidence.

Method Details

values

public static ReadAdvice[] values()

Returns an array containing the constants of this enum class, in the order they are declared.

Returns:

an array containing the constants of this enum class, in the order they are declared

valueOf

public static ReadAdvice valueOf(String name)

Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum class has no constant with the specified name

NullPointerException - if the argument is null