Netty5/Codec 5.0.0.Alpha5 · io.netty5.handler.codec.compression.Snappy

Modifier and Type	Class and Description
private static enum	Snappy.State

Modifier and Type	Field and Description
private static final int	COPY_1_BYTE_OFFSET
private static final int	COPY_2_BYTE_OFFSET
private static final int	COPY_4_BYTE_OFFSET
private static final int	LITERAL
private static final int	MAX_HT_SIZE
private static final int	MIN_COMPRESSIBLE_BYTES
private static final int	NOT_ENOUGH_INPUT
private static final int	PREAMBLE_NOT_FULL
private Snappy.State	state
private byte	tag
private int	written

Access	Constructor and Description
public	Snappy()

Method Summary

Modifier and Type	Method and Description
private static int	Returns: The minimum number of bits required to encode the supplied value bitsToEncode(int The value to calculate the minimum number of bits required to encode value) Calculates the minimum number of bits required to encode a value.
pack-priv static int	calculateChecksum(Buffer The input data to calculate the CRC32C checksum of data) Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum
pack-priv static int	calculateChecksum(Buffer The input data to calculate the CRC32C checksum of data, int offset, int length) Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum
private static void	copyRegion(Buffer out, int initialIndex, int offset, int length)
public void	decode(Buffer in, Buffer out)
private static int	Returns: The number of bytes appended to the output buffer, or -1 to indicate "try again later" decodeCopyWith1ByteOffset(byte The tag used to identify this as a copy is also used to encode the length and part of the offset tag, Buffer The input buffer to read from in, Buffer The output buffer to write to out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.
private static int	Returns: The number of bytes appended to the output buffer, or -1 to indicate "try again later" decodeCopyWith2ByteOffset(byte The tag used to identify this as a copy is also used to encode the length and part of the offset tag, Buffer The input buffer to read from in, Buffer The output buffer to write to out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.
private static int	Returns: The number of bytes appended to the output buffer, or -1 to indicate "try again later" decodeCopyWith4ByteOffset(byte The tag used to identify this as a copy is also used to encode the length and part of the offset tag, Buffer The input buffer to read from in, Buffer The output buffer to write to out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.
pack-priv static int	Returns: The number of bytes appended to the output buffer, or -1 to indicate "try again later" decodeLiteral(byte The tag that identified this segment as a literal is also used to encode part of the length of the data tag, Buffer The input buffer to read the literal from in, Buffer The output buffer to write the literal to out) Reads a literal from the input buffer directly to the output buffer.
public void	encode(final Buffer in, final Buffer out, final int length)
private static void	encodeCopy(Buffer The output buffer to write the copy pointer to out, int The offset at which the original instance lies offset, int The length of the original instance length) Encodes a series of copies, each at most 64 bytes in length.
private static void	encodeCopyWithOffset(Buffer out, int offset, int length)
pack-priv static void	encodeLiteral(Buffer The input buffer to copy from in, Buffer The output buffer to copy to out, int The length of the literal to copy length) Writes a literal to the supplied output buffer by directly copying from the input buffer.
private static int	Returns: The number of bytes for which our candidate copy is a repeat of findMatchingLength(Buffer The input buffer to scan over in, int The index in the input buffer to start scanning from minIndex, int The index of the start of our copy inIndex, int The length of our input buffer maxIndex) Iterates over the supplied input buffer between the supplied minIndex and maxIndex to find how long our matched copy overlaps with an already-written literal value.
private static short[]	Returns: An appropriately sized empty hashtable getHashTable(int The size of our input, ie. the number of bytes we need to encode inputSize) Creates an appropriately sized hashtable for the given input size
pack-priv int	Returns: The calculated length based on the input buffer, or 0 if no preamble is able to be calculated getPreamble(Buffer The input buffer to get the preamble from in) Get the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read).
private static int	Returns: A 32-bit hash of 4 bytes located at index hash(Buffer The input buffer to read 4 bytes from in, int The index to read at index, int The shift value, for ensuring that the resulting value is within the range of our hash table size shift) Hashes the 4 bytes located at index, shifting the resulting hash into the appropriate range for our hash table.
pack-priv static int	Returns: The masked checksum maskChecksum(long The actual checksum of the data checksum) From the spec: "Checksums are not stored directly, but masked, as checksumming data and then its own checksum can be problematic.
private static int	Returns: The calculated length based on the input buffer, or 0 if no preamble is able to be calculated readPreamble(Buffer The input buffer to read the preamble from in) Reads the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read).
public void	reset()
pack-priv static void	validateChecksum(int The checksum decoded from the stream to compare against expectedChecksum, Buffer The input data to calculate the CRC32C checksum of data) Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum.
pack-priv static void	validateChecksum(int The checksum decoded from the stream to compare against expectedChecksum, Buffer The input data to calculate the CRC32C checksum of data, int offset, int length) Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum.
private static void	validateOffset(int The offset extracted from the compressed reference offset, int The number of bytes read so far from this chunk chunkSizeSoFar) Validates that the offset extracted from a compressed reference is within the permissible bounds of an offset (0 < offset < Integer.MAX_VALUE), and does not exceed the length of the chunk currently read so far.

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

COPY_1_BYTE_OFFSET	back to summary
private static final int COPY_1_BYTE_OFFSET

COPY_2_BYTE_OFFSET	back to summary
private static final int COPY_2_BYTE_OFFSET

COPY_4_BYTE_OFFSET	back to summary
private static final int COPY_4_BYTE_OFFSET

LITERAL	back to summary
private static final int LITERAL

MAX_HT_SIZE	back to summary
private static final int MAX_HT_SIZE

MIN_COMPRESSIBLE_BYTES	back to summary
private static final int MIN_COMPRESSIBLE_BYTES

NOT_ENOUGH_INPUT	back to summary
private static final int NOT_ENOUGH_INPUT

PREAMBLE_NOT_FULL	back to summary
private static final int PREAMBLE_NOT_FULL

state	back to summary
private Snappy.State state

tag	back to summary
private byte tag

written	back to summary
private int written

Snappy	back to summary
public Snappy()

Method Detail

bitsToEncode	back to summary
private static int bitsToEncode(int value) Calculates the minimum number of bits required to encode a value. This can then in turn be used to calculate the number of septets or octets (as appropriate) to use to encode a length parameter. Parameters value:int The value to calculate the minimum number of bits required to encode Returns:int The minimum number of bits required to encode the supplied value

bitsToEncode

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private static int bitsToEncode(int value)

Calculates the minimum number of bits required to encode a value. This can then in turn be used to calculate the number of septets or octets (as appropriate) to use to encode a length parameter.

Parameters

value:int: The value to calculate the minimum number of bits required to encode

Returns:int

The minimum number of bits required to encode the supplied value

calculateChecksum	back to summary
pack-priv static int calculateChecksum(Buffer data) Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum Parameters data:Buffer The input data to calculate the CRC32C checksum of

calculateChecksum

back to summary

pack-priv static int calculateChecksum(Buffer data)

Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum

Parameters

data:Buffer: The input data to calculate the CRC32C checksum of

calculateChecksum	back to summary
pack-priv static int calculateChecksum(Buffer data, int offset, int length) Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum Parameters data:Buffer The input data to calculate the CRC32C checksum of

calculateChecksum

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pack-priv static int calculateChecksum(Buffer data, int offset, int length)

Computes the CRC32C checksum of the supplied data and performs the "mask" operation on the computed checksum

Parameters

data:Buffer: The input data to calculate the CRC32C checksum of

copyRegion	back to summary
private static void copyRegion(Buffer out, int initialIndex, int offset, int length)

decode	back to summary
public void decode(Buffer in, Buffer out)

decodeCopyWith1ByteOffset	back to summary
private static int decodeCopyWith1ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream. Parameters tag:byte The tag used to identify this as a copy is also used to encode the length and part of the offset in:Buffer The input buffer to read from out:Buffer The output buffer to write to Returns:int The number of bytes appended to the output buffer, or -1 to indicate "try again later" Exceptions DecompressionException: If the read offset is invalid

decodeCopyWith1ByteOffset

back to summary

private static int decodeCopyWith1ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar)

Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.

Parameters

tag:byte: The tag used to identify this as a copy is also used to encode the length and part of the offset
in:Buffer: The input buffer to read from
out:Buffer: The output buffer to write to

Returns:int

The number of bytes appended to the output buffer, or -1 to indicate "try again later"

Exceptions

DecompressionException:: If the read offset is invalid

decodeCopyWith2ByteOffset	back to summary
private static int decodeCopyWith2ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream. Parameters tag:byte The tag used to identify this as a copy is also used to encode the length and part of the offset in:Buffer The input buffer to read from out:Buffer The output buffer to write to Returns:int The number of bytes appended to the output buffer, or -1 to indicate "try again later" Exceptions DecompressionException: If the read offset is invalid

decodeCopyWith2ByteOffset

back to summary

private static int decodeCopyWith2ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar)

Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.

Parameters

tag:byte: The tag used to identify this as a copy is also used to encode the length and part of the offset
in:Buffer: The input buffer to read from
out:Buffer: The output buffer to write to

Returns:int

The number of bytes appended to the output buffer, or -1 to indicate "try again later"

Exceptions

DecompressionException:: If the read offset is invalid

decodeCopyWith4ByteOffset	back to summary
private static int decodeCopyWith4ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar) Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream. Parameters tag:byte The tag used to identify this as a copy is also used to encode the length and part of the offset in:Buffer The input buffer to read from out:Buffer The output buffer to write to Returns:int The number of bytes appended to the output buffer, or -1 to indicate "try again later" Exceptions DecompressionException: If the read offset is invalid

decodeCopyWith4ByteOffset

back to summary

private static int decodeCopyWith4ByteOffset(byte tag, Buffer in, Buffer out, int writtenSoFar)

Reads a compressed reference offset and length from the supplied input buffer, seeks back to the appropriate place in the input buffer and writes the found data to the supplied output stream.

Parameters

tag:byte: The tag used to identify this as a copy is also used to encode the length and part of the offset
in:Buffer: The input buffer to read from
out:Buffer: The output buffer to write to

Returns:int

The number of bytes appended to the output buffer, or -1 to indicate "try again later"

Exceptions

DecompressionException:: If the read offset is invalid

decodeLiteral	back to summary
pack-priv static int decodeLiteral(byte tag, Buffer in, Buffer out) Reads a literal from the input buffer directly to the output buffer. A "literal" is an uncompressed segment of data stored directly in the byte stream. Parameters tag:byte The tag that identified this segment as a literal is also used to encode part of the length of the data in:Buffer The input buffer to read the literal from out:Buffer The output buffer to write the literal to Returns:int The number of bytes appended to the output buffer, or -1 to indicate "try again later"

decodeLiteral

back to summary

pack-priv static int decodeLiteral(byte tag, Buffer in, Buffer out)

Reads a literal from the input buffer directly to the output buffer. A "literal" is an uncompressed segment of data stored directly in the byte stream.

Parameters

tag:byte: The tag that identified this segment as a literal is also used to encode part of the length of the data
in:Buffer: The input buffer to read the literal from
out:Buffer: The output buffer to write the literal to

Returns:int

The number of bytes appended to the output buffer, or -1 to indicate "try again later"

encode	back to summary
public void encode(final Buffer in, final Buffer out, final int length)

encodeCopy	back to summary
private static void encodeCopy(Buffer out, int offset, int length) Encodes a series of copies, each at most 64 bytes in length. Parameters out:Buffer The output buffer to write the copy pointer to offset:int The offset at which the original instance lies length:int The length of the original instance

encodeCopy

back to summary

private static void encodeCopy(Buffer out, int offset, int length)

Encodes a series of copies, each at most 64 bytes in length.

Parameters

out:Buffer: The output buffer to write the copy pointer to
offset:int: The offset at which the original instance lies
length:int: The length of the original instance

encodeCopyWithOffset	back to summary
private static void encodeCopyWithOffset(Buffer out, int offset, int length)

encodeLiteral	back to summary
pack-priv static void encodeLiteral(Buffer in, Buffer out, int length) Writes a literal to the supplied output buffer by directly copying from the input buffer. The literal is taken from the current readerIndex up to the supplied length. Parameters in:Buffer The input buffer to copy from out:Buffer The output buffer to copy to length:int The length of the literal to copy

encodeLiteral

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pack-priv static void encodeLiteral(Buffer in, Buffer out, int length)

Writes a literal to the supplied output buffer by directly copying from the input buffer. The literal is taken from the current readerIndex up to the supplied length.

Parameters

in:Buffer: The input buffer to copy from
out:Buffer: The output buffer to copy to
length:int: The length of the literal to copy

findMatchingLength	back to summary
private static int findMatchingLength(Buffer in, int minIndex, int inIndex, int maxIndex) Iterates over the supplied input buffer between the supplied minIndex and maxIndex to find how long our matched copy overlaps with an already-written literal value. Parameters in:Buffer The input buffer to scan over minIndex:int The index in the input buffer to start scanning from inIndex:int The index of the start of our copy maxIndex:int The length of our input buffer Returns:int The number of bytes for which our candidate copy is a repeat of

findMatchingLength

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private static int findMatchingLength(Buffer in, int minIndex, int inIndex, int maxIndex)

Iterates over the supplied input buffer between the supplied minIndex and maxIndex to find how long our matched copy overlaps with an already-written literal value.

Parameters

in:Buffer: The input buffer to scan over
minIndex:int: The index in the input buffer to start scanning from
inIndex:int: The index of the start of our copy
maxIndex:int: The length of our input buffer

Returns:int

The number of bytes for which our candidate copy is a repeat of

getHashTable	back to summary
private static short[] getHashTable(int inputSize) Creates an appropriately sized hashtable for the given input size Parameters inputSize:int The size of our input, ie. the number of bytes we need to encode Returns:short[] An appropriately sized empty hashtable

getHashTable

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private static short[] getHashTable(int inputSize)

Creates an appropriately sized hashtable for the given input size

Parameters

inputSize:int: The size of our input, ie. the number of bytes we need to encode

Returns:short[]

An appropriately sized empty hashtable

getPreamble	back to summary
pack-priv int getPreamble(Buffer in) Get the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read). Parameters in:Buffer The input buffer to get the preamble from Returns:int The calculated length based on the input buffer, or 0 if no preamble is able to be calculated

getPreamble

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pack-priv int getPreamble(Buffer in)

Get the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read).

Parameters

in:Buffer: The input buffer to get the preamble from

Returns:int

The calculated length based on the input buffer, or 0 if no preamble is able to be calculated

hash	back to summary
private static int hash(Buffer in, int index, int shift) Hashes the 4 bytes located at index, shifting the resulting hash into the appropriate range for our hash table. Parameters in:Buffer The input buffer to read 4 bytes from index:int The index to read at shift:int The shift value, for ensuring that the resulting value is within the range of our hash table size Returns:int A 32-bit hash of 4 bytes located at index

hash

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private static int hash(Buffer in, int index, int shift)

Hashes the 4 bytes located at index, shifting the resulting hash into the appropriate range for our hash table.

Parameters

in:Buffer: The input buffer to read 4 bytes from
index:int: The index to read at
shift:int: The shift value, for ensuring that the resulting value is within the range of our hash table size

Returns:int

A 32-bit hash of 4 bytes located at index

maskChecksum	back to summary
pack-priv static int maskChecksum(long checksum) From the spec: "Checksums are not stored directly, but masked, as checksumming data and then its own checksum can be problematic. The masking is the same as used in Apache Hadoop: Rotate the checksum by 15 bits, then add the constant 0xa282ead8 (using wraparound as normal for unsigned integers)." Parameters checksum:long The actual checksum of the data Returns:int The masked checksum

maskChecksum

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pack-priv static int maskChecksum(long checksum)

From the spec: "Checksums are not stored directly, but masked, as checksumming data and then its own checksum can be problematic. The masking is the same as used in Apache Hadoop: Rotate the checksum by 15 bits, then add the constant 0xa282ead8 (using wraparound as normal for unsigned integers)."

Parameters

checksum:long: The actual checksum of the data

Returns:int

The masked checksum

readPreamble	back to summary
private static int readPreamble(Buffer in) Reads the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read). Parameters in:Buffer The input buffer to read the preamble from Returns:int The calculated length based on the input buffer, or 0 if no preamble is able to be calculated

readPreamble

back to summary

private static int readPreamble(Buffer in)

Reads the length varint (a series of bytes, where the lower 7 bits are data and the upper bit is a flag to indicate more bytes to be read).

Parameters

in:Buffer: The input buffer to read the preamble from

Returns:int

The calculated length based on the input buffer, or 0 if no preamble is able to be calculated

reset	back to summary
public void reset()

validateChecksum	back to summary
pack-priv static void validateChecksum(int expectedChecksum, Buffer data) Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum. Parameters expectedChecksum:int The checksum decoded from the stream to compare against data:Buffer The input data to calculate the CRC32C checksum of Exceptions DecompressionException: If the calculated and supplied checksums do not match

validateChecksum

back to summary

pack-priv static void validateChecksum(int expectedChecksum, Buffer data)

Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum.

Parameters

expectedChecksum:int: The checksum decoded from the stream to compare against
data:Buffer: The input data to calculate the CRC32C checksum of

Exceptions

DecompressionException:: If the calculated and supplied checksums do not match

validateChecksum	back to summary
pack-priv static void validateChecksum(int expectedChecksum, Buffer data, int offset, int length) Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum. Parameters expectedChecksum:int The checksum decoded from the stream to compare against data:Buffer The input data to calculate the CRC32C checksum of Exceptions DecompressionException: If the calculated and supplied checksums do not match

validateChecksum

back to summary

pack-priv static void validateChecksum(int expectedChecksum, Buffer data, int offset, int length)

Computes the CRC32C checksum of the supplied data, performs the "mask" operation on the computed checksum, and then compares the resulting masked checksum to the supplied checksum.

Parameters

expectedChecksum:int: The checksum decoded from the stream to compare against
data:Buffer: The input data to calculate the CRC32C checksum of

Exceptions

DecompressionException:: If the calculated and supplied checksums do not match

validateOffset	back to summary
private static void validateOffset(int offset, int chunkSizeSoFar) Validates that the offset extracted from a compressed reference is within the permissible bounds of an offset (0 < offset < Integer.MAX_VALUE), and does not exceed the length of the chunk currently read so far. Parameters offset:int The offset extracted from the compressed reference chunkSizeSoFar:int The number of bytes read so far from this chunk Exceptions DecompressionException: if the offset is invalid

validateOffset

back to summary

private static void validateOffset(int offset, int chunkSizeSoFar)

Validates that the offset extracted from a compressed reference is within the permissible bounds of an offset (0 < offset < Integer.MAX_VALUE), and does not exceed the length of the chunk currently read so far.

Parameters

offset:int: The offset extracted from the compressed reference
chunkSizeSoFar:int: The number of bytes read so far from this chunk

Exceptions

DecompressionException:: if the offset is invalid

Modifier and Type	Field and Description
public static final Snappy.State	READING_COPY
public static final Snappy.State	READING_LITERAL
public static final Snappy.State	READING_PREAMBLE
public static final Snappy.State	READING_TAG

Modifier and Type	Method and Description
public static Snappy.State	valueOf(String name)
public static Snappy.State[]	values()

public final Class Snappy

Nested and Inner Type Summary

Field Summary

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Field Detail

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Method Detail

private final Enum Snappy.State

Field Summary

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