com.datastax.driver.core

Class CodecUtils

java.lang.Object

com.datastax.driver.core.CodecUtils

public final class CodecUtils
extends Object

A set of utility methods to deal with type conversion and serialization.

Method Summary

Modifier and Type	Method and Description
static int	fromCqlDateToDaysSinceEpoch(long raw) Convert from a raw CQL long representing a numeric DATE literal to the number of days since the Epoch.
static long	fromDaysSinceEpochToCqlDate(int days) Convert the number of days since the Epoch into a raw CQL long representing a numeric DATE literal.
static int	fromSignedToUnsignedInt(int signed) Converts an int into an "unsigned" int suitable to be written as a DATE value.
static int	fromUnsignedToSignedInt(int unsigned) Converts an "unsigned" int read from a DATE value into a signed int.
static ByteBuffer	pack(ByteBuffer[] buffers, int elements, ProtocolVersion version) Utility method that "packs" together a list of ByteBuffers containing serialized collection elements.
static ByteBuffer	readBytes(ByteBuffer bb, int length) Read length bytes from bb into a new ByteBuffer.
static int	readSize(ByteBuffer input, ProtocolVersion version) Utility method that reads a size value.
static ByteBuffer	readValue(ByteBuffer input, ProtocolVersion version) Utility method that reads a value.
static void	writeSize(ByteBuffer output, int size, ProtocolVersion version) Utility method that writes a size value.
static void	writeValue(ByteBuffer output, ByteBuffer value, ProtocolVersion version) Utility method that writes a value.

Methods inherited from class java.lang.Object

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

Method Detail

pack

public static ByteBuffer pack(ByteBuffer[] buffers,
                              int elements,
                              ProtocolVersion version)

Utility method that "packs" together a list of ByteBuffers containing serialized collection elements. Mainly intended for use with collection codecs when serializing collections.

Parameters:

buffers - the collection elements

elements - the total number of elements

version - the protocol version to use

Returns:

The serialized collection

readSize

public static int readSize(ByteBuffer input,
                           ProtocolVersion version)

Utility method that reads a size value. Mainly intended for collection codecs when deserializing CQL collections.

Parameters:

input - The ByteBuffer to read from.

version - The protocol version to use.

Returns:

The size value.

writeSize

public static void writeSize(ByteBuffer output,
                             int size,
                             ProtocolVersion version)

Utility method that writes a size value. Mainly intended for collection codecs when serializing CQL collections.

Parameters:

output - The ByteBuffer to write to.

size - The collection size.

version - The protocol version to use.

readValue

public static ByteBuffer readValue(ByteBuffer input,
                                   ProtocolVersion version)

Utility method that reads a value. Mainly intended for collection codecs when deserializing CQL collections.

Parameters:

input - The ByteBuffer to read from.

version - The protocol version to use.

Returns:

The collection element.

writeValue

public static void writeValue(ByteBuffer output,
                              ByteBuffer value,
                              ProtocolVersion version)

Utility method that writes a value. Mainly intended for collection codecs when deserializing CQL collections.

Parameters:

output - The ByteBuffer to write to.

value - The value to write.

version - The protocol version to use.

readBytes

public static ByteBuffer readBytes(ByteBuffer bb,
                                   int length)

Read length bytes from bb into a new ByteBuffer.

Parameters:

bb - The ByteBuffer to read.

length - The number of bytes to read.

Returns:

The read bytes.

fromUnsignedToSignedInt

public static int fromUnsignedToSignedInt(int unsigned)

Converts an "unsigned" int read from a DATE value into a signed int.

The protocol encodes DATE values as unsigned ints with the Epoch in the middle of the range (2^31). This method handles the conversion from an "unsigned" to a signed int.

fromSignedToUnsignedInt

public static int fromSignedToUnsignedInt(int signed)

Converts an int into an "unsigned" int suitable to be written as a DATE value.

The protocol encodes DATE values as unsigned ints with the Epoch in the middle of the range (2^31). This method handles the conversion from a signed to an "unsigned" int.

fromCqlDateToDaysSinceEpoch

public static int fromCqlDateToDaysSinceEpoch(long raw)

Convert from a raw CQL long representing a numeric DATE literal to the number of days since the Epoch. In CQL, numeric DATE literals are longs (unsigned integers actually) between 0 and 2^32 - 1, with the epoch in the middle; this method re-centers the epoch at 0.

Parameters:

raw - The CQL date value to convert.

Returns:

The number of days since the Epoch corresponding to the given raw value.

Throws:

IllegalArgumentException - if the value is out of range.

fromDaysSinceEpochToCqlDate

public static long fromDaysSinceEpochToCqlDate(int days)

Convert the number of days since the Epoch into a raw CQL long representing a numeric DATE literal.

In CQL, numeric DATE literals are longs (unsigned integers actually) between 0 and 2^32 - 1, with the epoch in the middle; this method re-centers the epoch at 2^31.

Parameters:

days - The number of days since the Epoch convert.

Returns:

The CQL date value corresponding to the given value.