Interface TwoPhaseCommands

All Known Implementing Classes:

TwoPhaseCommands.CoordDecide, TwoPhaseCommands.CoordPrepare, TwoPhaseCommands.DecideAck, TwoPhaseCommands.DecideGroup, TwoPhaseCommands.DecideQuery, TwoPhaseCommands.PrepareAck, TwoPhaseCommands.PrepareGroup

public sealed interface TwoPhaseCommands
permits TwoPhaseCommands.PrepareGroup, TwoPhaseCommands.PrepareAck, TwoPhaseCommands.DecideGroup, TwoPhaseCommands.DecideAck, TwoPhaseCommands.DecideQuery, TwoPhaseCommands.CoordPrepare, TwoPhaseCommands.CoordDecide

Sealed command types for the cross-group 2PC protocol introduced in BLK-2026-04-22-001 Phase C.

Each command is serialized via a manual DataOutputStream layout (no Kryo dependency) so the wire format is stable across versions and does not participate in the Kryo-ID lock-in table.

Foundation-only commit: command records + serialize/deserialize methods. Coordinator + participant + CacheNode dispatch follow in subsequent commits. HARD SAFETY RAIL 5 (Raft apply invariants) is preserved because this commit adds types but does not change any apply-path code.

Sealed hierarchy:

  TwoPhaseCommand
    ├─ PrepareGroup     — coordinator -> participant group leader
    ├─ PrepareAck       — participant group -> coordinator
    ├─ DecideGroup      — coordinator -> participant group leader
    ├─ DecideAck        — participant group -> coordinator
    └─ DecideQuery      — recovering participant -> coordinator

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static final record	TwoPhaseCommands.CoordDecide	Durable coordinator DECIDE record, replicated through raft-0's own log BEFORE the coordinator fans TX_DECIDE_GROUP out to the participant groups.
static final record	TwoPhaseCommands.CoordPrepare	Durable coordinator PREPARE record, replicated through raft-0's own log.
static final record	TwoPhaseCommands.DecideAck	Acknowledgment from a participant that it applied the coordinator's decision.
static final record	TwoPhaseCommands.DecideGroup	Phase-2 decision broadcast from the coordinator to each participant.
static final record	TwoPhaseCommands.DecideQuery	Query from a recovering participant to the coordinator: "what decision did you make for this transaction?"
static enum	TwoPhaseCommands.Decision	Coordinator decision in phase 2.
static interface	TwoPhaseCommands.FrameWriter	Internal writer callback used by writeFrame(TwoPhaseCommands.Kind, TwoPhaseCommands.FrameWriter).
static enum	TwoPhaseCommands.Kind	Wire kind tag — serialized as the first byte of every frame.
static final record	TwoPhaseCommands.PrepareAck	Phase-1 vote from a participant group back to the coordinator.
static final record	TwoPhaseCommands.PrepareGroup	Transaction phase-1 request from coordinator to a participant group.
static enum	TwoPhaseCommands.Vote	Participant vote in phase 1.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	MAX_OPERATION_PAYLOAD_BYTES
static final int	MAX_PARTICIPANT_GROUP_COUNT
static final int	MAX_REASON_UTF_BYTES

Method Summary

Static Methods

Modifier and Type	Method	Description
static @NonNull TwoPhaseCommands	deserialize(byte @NonNull [] bytes)	Deserialize a wire frame into the matching command record.
static @NonNull List<Class<? extends TwoPhaseCommands>>	knownTypes()
static byte @NonNull []	serialize(@NonNull TwoPhaseCommands cmd)	Serialize any command instance.

Field Details

MAX_PARTICIPANT_GROUP_COUNT

static final int MAX_PARTICIPANT_GROUP_COUNT

See Also:

• Constant Field Values

MAX_OPERATION_PAYLOAD_BYTES

static final int MAX_OPERATION_PAYLOAD_BYTES

See Also:

• Constant Field Values

MAX_REASON_UTF_BYTES

static final int MAX_REASON_UTF_BYTES

See Also:

• Constant Field Values

Method Details

deserialize

static @NonNull TwoPhaseCommands deserialize(byte @NonNull [] bytes)

Deserialize a wire frame into the matching command record.

Parameters:

bytes - the wire frame (first byte is the Kind ordinal)

Returns:

the parsed command

Throws:

IllegalArgumentException - if the frame is truncated / has an unknown kind

serialize

static byte @NonNull [] serialize(@NonNull TwoPhaseCommands cmd)

Serialize any command instance. Sugar over the per-record serialize methods so callers can take a polymorphic TwoPhaseCommands reference.

knownTypes

static @NonNull List<Class<? extends TwoPhaseCommands>> knownTypes()

Returns:

the list of all TwoPhaseCommands sealed subtypes. Useful for dispatch tables and test coverage assertions.