Modifier and Type	Class and Description
public static class	Parameters.Builder Builder for `Parameters` instances.

Modifier and Type	Field and Description
private final boolean	lazyMatching
private final int	lazyThreshold
private final int	maxBackReferenceLength
private final int	maxCandidates
private final int	maxLiteralLength
private final int	maxOffset
private final int	minBackReferenceLength
private final int	niceBackReferenceLength
public static final int	TRUE_MIN_BACK_REFERENCE_LENGTH The hard-coded absolute minimal length of a back-reference.
private final int	windowSize

Access	Constructor and Description
private	Parameters(final int windowSize, final int minBackReferenceLength, final int maxBackReferenceLength, final int maxOffset, final int maxLiteralLength, final int niceBackReferenceLength, final int maxCandidates, final boolean lazyMatching, final int lazyThreshold)

Method Summary

Modifier and Type	Method and Description
public static Parameters.Builder	Returns: a builder configured for the given window size builder(final int the size of the sliding window - this determines the maximum offset a back-reference can take. Must be a power of two. windowSize) Initializes the builder for the compressor's parameters with a `minBackReferenceLength` of 3 and `max*Length` equal to `windowSize - 1`.
public boolean	Returns: whether to perform lazy matching getLazyMatching() Gets whether to perform lazy matching.
public int	Returns: the threshold for lazy matching getLazyMatchingThreshold() Gets the threshold for lazy matching.
public int	Returns: the maximal length of a back-reference found getMaxBackReferenceLength() Gets the maximal length of a back-reference found.
public int	Returns: the maximum number of back-reference candidates to consider getMaxCandidates() Gets the maximum number of back-reference candidates to consider.
public int	Returns: the maximal length of a literal block getMaxLiteralLength() Gets the maximal length of a literal block.
public int	Returns: the maximal offset of a back-reference found getMaxOffset() Gets the maximal offset of a back-reference found.
public int	Returns: the minimal length of a back-reference found getMinBackReferenceLength() Gets the minimal length of a back-reference found.
public int	Returns: the length of a back-reference that is considered nice enough to stop searching getNiceBackReferenceLength() Gets the length of a back-reference that is considered nice enough to stop searching for longer ones.
public int	Returns: the size of the sliding window getWindowSize() Gets the size of the sliding window - this determines the maximum offset a back-reference can take.
private static boolean	isPowerOfTwo(final int x)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

lazyMatching	back to summary
private final boolean lazyMatching

lazyThreshold	back to summary
private final int lazyThreshold

maxBackReferenceLength	back to summary
private final int maxBackReferenceLength

maxCandidates	back to summary
private final int maxCandidates

maxLiteralLength	back to summary
private final int maxLiteralLength

maxOffset	back to summary
private final int maxOffset

minBackReferenceLength	back to summary
private final int minBackReferenceLength

niceBackReferenceLength	back to summary
private final int niceBackReferenceLength

TRUE_MIN_BACK_REFERENCE_LENGTH	back to summary
public static final int TRUE_MIN_BACK_REFERENCE_LENGTH The hard-coded absolute minimal length of a back-reference.

windowSize	back to summary
private final int windowSize

Parameters	back to summary
private Parameters(final int windowSize, final int minBackReferenceLength, final int maxBackReferenceLength, final int maxOffset, final int maxLiteralLength, final int niceBackReferenceLength, final int maxCandidates, final boolean lazyMatching, final int lazyThreshold)

Method Detail

builder back to summary

builder	back to summary
public static Parameters.Builder builder(final int windowSize) Initializes the builder for the compressor's parameters with a `minBackReferenceLength` of 3 and `max*Length` equal to `windowSize - 1`. It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like `org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder`. Parameters windowSize:int the size of the sliding window - this determines the maximum offset a back-reference can take. Must be a power of two. Returns:Parameters.Builder a builder configured for the given window size Exceptions IllegalArgumentException: if windowSize is not a power of two.

public static Parameters.Builder builder(final int windowSize)

Initializes the builder for the compressor's parameters with a minBackReferenceLength of 3 and max*Length equal to windowSize - 1.

It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder.

Parameters

windowSize:int: the size of the sliding window - this determines the maximum offset a back-reference can take. Must be a power of two.

Returns:Parameters.Builder

a builder configured for the given window size

Exceptions

IllegalArgumentException:: if windowSize is not a power of two.

getLazyMatching	back to summary
public boolean getLazyMatching() Gets whether to perform lazy matching. Returns:boolean whether to perform lazy matching

getLazyMatching

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public boolean getLazyMatching()

Gets whether to perform lazy matching.

Returns:boolean: whether to perform lazy matching

getLazyMatchingThreshold	back to summary
public int getLazyMatchingThreshold() Gets the threshold for lazy matching. Returns:int the threshold for lazy matching

getLazyMatchingThreshold

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public int getLazyMatchingThreshold()

Gets the threshold for lazy matching.

Returns:int: the threshold for lazy matching

getMaxBackReferenceLength	back to summary
public int getMaxBackReferenceLength() Gets the maximal length of a back-reference found. Returns:int the maximal length of a back-reference found

getMaxBackReferenceLength

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public int getMaxBackReferenceLength()

Gets the maximal length of a back-reference found.

Returns:int: the maximal length of a back-reference found

getMaxCandidates	back to summary
public int getMaxCandidates() Gets the maximum number of back-reference candidates to consider. Returns:int the maximum number of back-reference candidates to consider

getMaxCandidates

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public int getMaxCandidates()

Gets the maximum number of back-reference candidates to consider.

Returns:int: the maximum number of back-reference candidates to consider

getMaxLiteralLength	back to summary
public int getMaxLiteralLength() Gets the maximal length of a literal block. Returns:int the maximal length of a literal block

getMaxLiteralLength

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public int getMaxLiteralLength()

Gets the maximal length of a literal block.

Returns:int: the maximal length of a literal block

getMaxOffset	back to summary
public int getMaxOffset() Gets the maximal offset of a back-reference found. Returns:int the maximal offset of a back-reference found

getMaxOffset

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public int getMaxOffset()

Gets the maximal offset of a back-reference found.

Returns:int: the maximal offset of a back-reference found

getMinBackReferenceLength	back to summary
public int getMinBackReferenceLength() Gets the minimal length of a back-reference found. Returns:int the minimal length of a back-reference found

getMinBackReferenceLength

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public int getMinBackReferenceLength()

Gets the minimal length of a back-reference found.

Returns:int: the minimal length of a back-reference found

getNiceBackReferenceLength	back to summary
public int getNiceBackReferenceLength() Gets the length of a back-reference that is considered nice enough to stop searching for longer ones. Returns:int the length of a back-reference that is considered nice enough to stop searching

getNiceBackReferenceLength

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public int getNiceBackReferenceLength()

Gets the length of a back-reference that is considered nice enough to stop searching for longer ones.

Returns:int: the length of a back-reference that is considered nice enough to stop searching

getWindowSize	back to summary
public int getWindowSize() Gets the size of the sliding window - this determines the maximum offset a back-reference can take. Returns:int the size of the sliding window

getWindowSize

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public int getWindowSize()

Gets the size of the sliding window - this determines the maximum offset a back-reference can take.

Returns:int: the size of the sliding window

isPowerOfTwo	back to summary
private static boolean isPowerOfTwo(final int x)

org.apache.commons.compress.compressors.lz77support back to summary

public Class Parameters.Builder

Class Inheritance

extends Object

java.lang.Object
org.apache.commons.compress.compressors.lz77support.Parameters.Builder

Builder for Parameters instances.

Field Summary

Modifier and Type	Field and Description
private Boolean	lazyMatches
private Integer	lazyThreshold
private int	maxBackReferenceLength
private Integer	maxCandidates
private int	maxLiteralLength
private int	maxOffset
private int	minBackReferenceLength
private Integer	niceBackReferenceLength
private final int	windowSize

Constructor Summary

Access	Constructor and Description
private	Builder(final int windowSize)

Method Summary

Modifier and Type	Method and Description
public Parameters	Returns: the configured `Parameters` instance. build() Creates the `Parameters` instance.
public Parameters.Builder	Returns: the builder tunedForCompressionRatio() Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression ratio at the cost of compression speed.
public Parameters.Builder	Returns: the builder tunedForSpeed() Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression speed at the cost of compression ratio.
public Parameters.Builder	Returns: the builder withLazyMatching(final boolean whether lazy matching should be performed lazy) Sets whether lazy matching should be performed.
public Parameters.Builder	Returns: the builder withLazyThreshold(final int the threshold for lazy matching threshold) Sets the threshold for lazy matching.
public Parameters.Builder	Returns: the builder withMaxBackReferenceLength(final int maximal length of a back-reference found. A value smaller than `minBackReferenceLength` is interpreted as `minBackReferenceLength`. `maxBackReferenceLength` is capped at `windowSize - 1`. maxBackReferenceLength) Sets the maximal length of a back-reference.
public Parameters.Builder	Returns: the builder withMaxLiteralLength(final int maximal length of a literal block. Negative numbers and 0 as well as values bigger than `windowSize` are interpreted as `windowSize`. maxLiteralLength) Sets the maximal length of a literal block.
public Parameters.Builder	Returns: the builder withMaxNumberOfCandidates(final int maximum number of back-reference candidates maxCandidates) Sets the maximum number of back-reference candidates that should be consulted.
public Parameters.Builder	Returns: the builder withMaxOffset(final int maximal offset of a back-reference. A non-positive value as well as values bigger than `windowSize - 1` are interpreted as `windowSize - 1` . maxOffset) Sets the maximal offset of a back-reference.
public Parameters.Builder	Returns: the builder withMinBackReferenceLength(final int the minimal length of a back-reference found. A true minimum of 3 is hard-coded inside of this implementation but bigger lengths can be configured. minBackReferenceLength) Sets the minimal length of a back-reference.
public Parameters.Builder	Returns: the builder withNiceBackReferenceLength(final int the "nice length" of a back-reference niceLen) Sets the "nice length" of a back-reference.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

lazyMatches	back to summary
private Boolean lazyMatches

lazyThreshold	back to summary
private Integer lazyThreshold

maxBackReferenceLength	back to summary
private int maxBackReferenceLength

maxCandidates	back to summary
private Integer maxCandidates

maxLiteralLength	back to summary
private int maxLiteralLength

maxOffset	back to summary
private int maxOffset

minBackReferenceLength	back to summary
private int minBackReferenceLength

niceBackReferenceLength	back to summary
private Integer niceBackReferenceLength

windowSize	back to summary
private final int windowSize

Constructor Detail

Builder	back to summary
private Builder(final int windowSize)

Method Detail

build back to summary

build	back to summary
public Parameters build() Creates the `Parameters` instance. Returns:Parameters the configured `Parameters` instance.

public Parameters build()

Creates the Parameters instance.

Returns:Parameters: the configured Parameters instance.

tunedForCompressionRatio	back to summary
public Parameters.Builder tunedForCompressionRatio() Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression ratio at the cost of compression speed. Use this method after configuring "maximum back-reference length". Returns:Parameters.Builder the builder

tunedForCompressionRatio

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public Parameters.Builder tunedForCompressionRatio()

Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression ratio at the cost of compression speed.

Use this method after configuring "maximum back-reference length".

Returns:Parameters.Builder: the builder

tunedForSpeed	back to summary
public Parameters.Builder tunedForSpeed() Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression speed at the cost of compression ratio. Use this method after configuring "maximum back-reference length". Returns:Parameters.Builder the builder

tunedForSpeed

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public Parameters.Builder tunedForSpeed()

Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression speed at the cost of compression ratio.

Use this method after configuring "maximum back-reference length".

Returns:Parameters.Builder: the builder

withLazyMatching	back to summary
public Parameters.Builder withLazyMatching(final boolean lazy) Sets whether lazy matching should be performed. Lazy matching means that after a back-reference for a certain position has been found the compressor will try to find a longer match for the next position. Lazy matching is enabled by default and disabled when tuning for speed. Parameters lazy:boolean whether lazy matching should be performed Returns:Parameters.Builder the builder

withLazyMatching

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public Parameters.Builder withLazyMatching(final boolean lazy)

Sets whether lazy matching should be performed.

Lazy matching means that after a back-reference for a certain position has been found the compressor will try to find a longer match for the next position.

Lazy matching is enabled by default and disabled when tuning for speed.

Parameters

lazy:boolean: whether lazy matching should be performed

Returns:Parameters.Builder

the builder

withLazyThreshold	back to summary
public Parameters.Builder withLazyThreshold(final int threshold) Sets the threshold for lazy matching. Even if lazy matching is enabled it will not be performed if the length of the back-reference found for the current position is longer than this value. Parameters threshold:int the threshold for lazy matching Returns:Parameters.Builder the builder

withLazyThreshold

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public Parameters.Builder withLazyThreshold(final int threshold)

Sets the threshold for lazy matching.

Even if lazy matching is enabled it will not be performed if the length of the back-reference found for the current position is longer than this value.

Parameters

threshold:int: the threshold for lazy matching

Returns:Parameters.Builder

the builder

withMaxBackReferenceLength back to summary

withMaxBackReferenceLength	back to summary
public Parameters.Builder withMaxBackReferenceLength(final int maxBackReferenceLength) Sets the maximal length of a back-reference. It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like `org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder`. Parameters maxBackReferenceLength:int maximal length of a back-reference found. A value smaller than `minBackReferenceLength` is interpreted as `minBackReferenceLength`. `maxBackReferenceLength` is capped at `windowSize - 1`. Returns:Parameters.Builder the builder

public Parameters.Builder withMaxBackReferenceLength(final int maxBackReferenceLength)

Sets the maximal length of a back-reference.

Parameters

maxBackReferenceLength:int: maximal length of a back-reference found. A value smaller than minBackReferenceLength is interpreted as minBackReferenceLength. maxBackReferenceLength is capped at windowSize - 1.

Returns:Parameters.Builder

the builder

withMaxLiteralLength back to summary

withMaxLiteralLength	back to summary
public Parameters.Builder withMaxLiteralLength(final int maxLiteralLength) Sets the maximal length of a literal block. It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like `org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder`. Parameters maxLiteralLength:int maximal length of a literal block. Negative numbers and 0 as well as values bigger than `windowSize` are interpreted as `windowSize`. Returns:Parameters.Builder the builder

public Parameters.Builder withMaxLiteralLength(final int maxLiteralLength)

Sets the maximal length of a literal block.

Parameters

maxLiteralLength:int: maximal length of a literal block. Negative numbers and 0 as well as values bigger than windowSize are interpreted as windowSize.

Returns:Parameters.Builder

the builder

withMaxNumberOfCandidates	back to summary
public Parameters.Builder withMaxNumberOfCandidates(final int maxCandidates) Sets the maximum number of back-reference candidates that should be consulted. This settings can be used to tune the tradeoff between compression speed and compression ratio. Parameters maxCandidates:int maximum number of back-reference candidates Returns:Parameters.Builder the builder

withMaxNumberOfCandidates

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public Parameters.Builder withMaxNumberOfCandidates(final int maxCandidates)

Sets the maximum number of back-reference candidates that should be consulted.

This settings can be used to tune the tradeoff between compression speed and compression ratio.

Parameters

maxCandidates:int: maximum number of back-reference candidates

Returns:Parameters.Builder

the builder

withMaxOffset back to summary

withMaxOffset	back to summary
public Parameters.Builder withMaxOffset(final int maxOffset) Sets the maximal offset of a back-reference. It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like `org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder`. Parameters maxOffset:int maximal offset of a back-reference. A non-positive value as well as values bigger than `windowSize - 1` are interpreted as `windowSize - 1` . Returns:Parameters.Builder the builder

public Parameters.Builder withMaxOffset(final int maxOffset)

Sets the maximal offset of a back-reference.

Parameters

maxOffset:int: maximal offset of a back-reference. A non-positive value as well as values bigger than windowSize - 1 are interpreted as windowSize - 1 .

Returns:Parameters.Builder

the builder

withMinBackReferenceLength back to summary

withMinBackReferenceLength	back to summary
public Parameters.Builder withMinBackReferenceLength(final int minBackReferenceLength) Sets the minimal length of a back-reference. Ensures `maxBackReferenceLength` is not smaller than `minBackReferenceLength`. It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like `org.apache.commons.compress.compressors.snappy.SnappyCompressorOutputStream#createParameterBuilder`. Parameters minBackReferenceLength:int the minimal length of a back-reference found. A true minimum of 3 is hard-coded inside of this implementation but bigger lengths can be configured. Returns:Parameters.Builder the builder Exceptions IllegalArgumentException: if `windowSize` is smaller than `minBackReferenceLength`.

public Parameters.Builder withMinBackReferenceLength(final int minBackReferenceLength)

Sets the minimal length of a back-reference.

Ensures maxBackReferenceLength is not smaller than minBackReferenceLength.

Parameters

minBackReferenceLength:int: the minimal length of a back-reference found. A true minimum of 3 is hard-coded inside of this implementation but bigger lengths can be configured.

Returns:Parameters.Builder

the builder

Exceptions

IllegalArgumentException:: if windowSize is smaller than minBackReferenceLength.

withNiceBackReferenceLength	back to summary
public Parameters.Builder withNiceBackReferenceLength(final int niceLen) Sets the "nice length" of a back-reference. When a back-references if this size has been found, stop searching for longer back-references. This settings can be used to tune the tradeoff between compression speed and compression ratio. Parameters niceLen:int the "nice length" of a back-reference Returns:Parameters.Builder the builder

withNiceBackReferenceLength

back to summary

public Parameters.Builder withNiceBackReferenceLength(final int niceLen)

Sets the "nice length" of a back-reference.

When a back-references if this size has been found, stop searching for longer back-references.

This settings can be used to tune the tradeoff between compression speed and compression ratio.

Parameters

niceLen:int: the "nice length" of a back-reference

Returns:Parameters.Builder

the builder

public final Class Parameters

Nested and Inner Type Summary

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail

public Class Parameters.Builder

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail