Package org.apache.accumulo.server.conf.codec

Class VersionedPropCodec

java.lang.Object

org.apache.accumulo.server.conf.codec.VersionedPropCodec

Direct Known Subclasses:

VersionedPropGzipCodec

public abstract class VersionedPropCodec
extends Object

Abstract class to provide encoding / decoding of versioned properties. This class handles the serialization of the metadata and subclasses are required to implement encodePayload(OutputStream, VersionedProperties, EncodingOptions) and decodePayload(InputStream, EncodingOptions) to handle any specific implementation metadata (optional) and the property map according to the encoding scheme of the subclass.

The basic encoding format:

• encoding metadata - specifies codec to be used
• version metadata - specifies property versioning information
• codec specific metadata (optional)
• the property map

Constructor Summary

Constructors

Constructor	Description
VersionedPropCodec(EncodingOptions encodingOpts)

Method Summary

Modifier and Type	Method	Description
@NonNull VersionedProperties	fromBytes(int version, byte[] bytes)
static VersionedPropCodec	getDefault()
EncodingOptions	getEncodingOpts()	The general encoding options that apply to all encodings.
static int	getEncodingVersion(byte[] bytes)	Extracts the encoding version from the encoded byte array without fully decoding the payload.
static Instant	readTimestamp(byte[] bytes)	Extracts the timestamp from the encoded byte array without fully decoding the payload.
byte[]	toBytes(VersionedProperties vProps)	Serialize the versioned properties.

Methods inherited from class java.lang.Object

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

Constructor Detail

VersionedPropCodec

public VersionedPropCodec(EncodingOptions encodingOpts)

Method Detail

getDefault

public static VersionedPropCodec getDefault()

getEncodingOpts

public EncodingOptions getEncodingOpts()

The general encoding options that apply to all encodings.

Returns:

the general options.

toBytes

public byte[] toBytes(VersionedProperties vProps)
               throws IOException

Serialize the versioned properties. The version information on the properties is updated if the data is successfully serialized.

Parameters:

vProps - the versioned properties.

Returns:

a byte array with the serialized properties.

Throws:

IOException

fromBytes

public @NonNull VersionedProperties fromBytes(int version,
                                              byte[] bytes)
                                       throws IOException

Parameters:

version - the data version determined by the prop store

bytes - an array of bytes created using a PropCodec.

Returns:

the versioned properties.

Throws:

IOException - if the an error occurs reading from the byte array.

getEncodingVersion

public static int getEncodingVersion(byte[] bytes)

Extracts the encoding version from the encoded byte array without fully decoding the payload. This is a convenience method if multiple encodings are present, and should only be required if upgrading / changing encodings, otherwise a single encoding should be in operation for an instance at any given time.

Parameters:

bytes - serialized encoded versioned property byte array.

Returns:

the encoding version used to serialize the properties.

readTimestamp

public static Instant readTimestamp(byte[] bytes)

Extracts the timestamp from the encoded byte array without fully decoding the payload. Normally the timestamp should be obtained from a fully decoded instance of the versioned properties.

The cost of reading the byte array from the backing store should be considered verses the additional cost of decoding - with a goal of reducing data reads from the store preferred. Generally reading from the store will be followed by some sort of usage which would require the full decode operation anyway, so uses of this method should be narrow and limited.

Parameters:

bytes - serialized encoded versioned property byte array.

Returns:

the timestamp used to serialize the properties.