Class MessageCodec

java.lang.Object

com.loomcache.common.protocol.MessageCodec

public final class MessageCodec
extends Object

Encodes/decodes Messages to/from the LoomCache binary wire protocol.

Wire format (16-byte header + variable body):

Offset Size Field ────── ──── ──────────────────────────── 0 1 Magic byte (0xDC) 1 1 Opcode (MessageType.code) 2 4 Correlation ID (big-endian int) 6 4 Body length (big-endian int) 10 1 Flags 11 2 Key length (big-endian short) 13 1 Status code 14 1 Map name length (0 = no map name, max 255 — single unsigned byte) 15 1 Protocol version (must match PROTOCOL_VERSION) ────── ──── ──────────────────────────── 16 N Body = [mapName bytes][key bytes][value bytes]

Key length is embedded in the header so we can split key and value from the body without an additional delimiter. Map name length allows the server to extract the target data structure name from client requests.

Backward compatible: old messages have mapNameLen=0 (was reserved/zero).

All multi-byte integers are BIG-ENDIAN (network byte order).

Constructor Summary

Constructors

Constructor	Description
MessageCodec()

Method Summary

Modifier and Type	Method	Description
static @Nullable Message	decode(InputStream in)	Decode a Message from an InputStream.
static @Nullable Message	decode(InputStream in, WireCompression negotiatedCompression)	Decode a Message from an InputStream using the negotiated compression mode.
static @Nullable Message	decode(ByteBuffer buf)	Decode from a ByteBuffer (for NIO channel reads).
static @Nullable Message	decode(ByteBuffer buf, WireCompression negotiatedCompression)	Decode from a ByteBuffer using the negotiated compression mode.
static ByteBuffer	encode(Message msg)	Encode a Message into a ByteBuffer (for NIO channel writes).
static ByteBuffer	encode(Message msg, WireCompression compression)	Encode a Message into a ByteBuffer using the negotiated compression mode.
static void	encode(Message msg, OutputStream out)	Encode a Message to an OutputStream (for traditional I/O).
static void	encode(Message msg, OutputStream out, WireCompression compression)	Encode a Message to an OutputStream using the negotiated compression mode.

Methods inherited from class Object

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

Constructor Details

MessageCodec

public MessageCodec()

Method Details

encode

public static ByteBuffer encode(Message msg)

Encode a Message into a ByteBuffer (for NIO channel writes). Returns a flipped buffer ready for writing.

encode

public static ByteBuffer encode(Message msg,
 WireCompression compression)

Encode a Message into a ByteBuffer using the negotiated compression mode.

encode

public static void encode(Message msg,
 OutputStream out)
                   throws IOException

Encode a Message to an OutputStream (for traditional I/O).

The entire message is encoded into a single byte array before writing, so either the complete message is written or nothing is (no partial header). The caller is responsible for ensuring the stream is not shared concurrently (e.g., via a write lock per connection).

Throws:

IOException - if the write or flush fails

encode

public static void encode(Message msg,
 OutputStream out,
 WireCompression compression)
                   throws IOException

Encode a Message to an OutputStream using the negotiated compression mode.

Throws:

IOException - if the write or flush fails

decode

public static @Nullable Message decode(InputStream in)
                                throws IOException

Decode a Message from an InputStream. Blocks until the full message is read. The caller must ensure each underlying read is bounded; for socket-backed streams, configure SO_TIMEOUT before calling this method. Returns null if stream is closed (EOF on header read).

Throws:

IOException

decode

public static @Nullable Message decode(InputStream in,
 WireCompression negotiatedCompression)
                                throws IOException

Decode a Message from an InputStream using the negotiated compression mode.

Throws:

IOException

decode

public static @Nullable Message decode(ByteBuffer buf)

Decode from a ByteBuffer (for NIO channel reads). Buffer must contain at least one complete message.

decode

public static @Nullable Message decode(ByteBuffer buf,
 WireCompression negotiatedCompression)

Decode from a ByteBuffer using the negotiated compression mode.