the byte to short refactor for nodeIdentifider

README.md

@@ -112,12 +112,12 @@ This is achieved by encoding the node identifier in each `N`s lower bits.
 This library uses a record with a signature similar to this:
 
 ```java
-public record BallotNumber(int counter, byte nodeIdentifier) implements Comparable<BallotNumber> {
+public record BallotNumber(int counter, short nodeIdentifier) implements Comparable<BallotNumber> {
 }
 ```
 
 The `compareTo` method treats the four-byte counter as having the most significant bits and the
-single-byte `nodeIndentifier` as having the least significant bits. The cluster operator must ensure they assign unique
+two-byte `nodeIndentifier` as having the least significant bits. The cluster operator must ensure they assign unique
 `nodeIdentifier` values to every node added to the cluster.
 
 In this implementation, nodes never recycle their numbers. They increment their counter each time they attempt to lead.
@@ -150,7 +150,7 @@ public record Command(String uuid,
                       byte[] operationBytes) {
 }
 
-public record BallotNumber(int counter, byte nodeIdentifier) {
+public record BallotNumber(int counter, short nodeIdentifier) {
 }
 
 public record Accept(long logIndex,
@@ -404,7 +404,7 @@ The list of tasks:
 - [x] Write a test harness that injects rolling network partitions.
 - [x] Write property based tests to exhaustively verify correctness.
 - [x] Write extensive documentation including detailed JavaDoc.
-- [ ] Include a record based distributed CAS as a default embedded pattern.
+- [ ] Write a transport for a demo. As Kwik does not support connection failover will start with my own UDP. 
 - [ ] Implement distributed advisor lock service as a full demo.
 - [ ] Implement cluster membership changes as UPaxos.
 - [ ] Add optionality so that randomized timeouts can be replaced by some other leader failure detection (e.g. JGroups).

trex-lib/src/main/java/com/github/trex_paxos/BallotNumber.java

@@ -19,14 +19,14 @@
 /// nodeIdentifier in the least significant fifth byte. This works as long as we make the nodeIdentifier unique within the cluster
 /// at any given configuration. It must also be unique across the overlaps of cluster membership reconfigurations. We can use Paxos itself to
 /// ensure this uniqueness.
-public record BallotNumber(int counter, byte nodeIdentifier) implements Comparable<BallotNumber> {
+public record BallotNumber(int counter, Short nodeIdentifier) implements Comparable<BallotNumber> {
 
-  public static final BallotNumber MIN = new BallotNumber(Integer.MIN_VALUE, Byte.MIN_VALUE);
+  public static final BallotNumber MIN = new BallotNumber(Integer.MIN_VALUE, Short.MIN_VALUE);
 
   @Override
   public int compareTo(BallotNumber that) {
     if (this.counter == that.counter) {
-      return Byte.compare(this.nodeIdentifier, that.nodeIdentifier);
+      return Short.compare(this.nodeIdentifier, that.nodeIdentifier);
     }
     return Integer.compare(this.counter, that.counter);
   }

trex-lib/src/main/java/com/github/trex_paxos/Journal.java

@@ -66,7 +66,7 @@ public interface Journal {
   ///
   /// @param nodeIdentifier The node identifier to load the progress record for. To avoid accidentally loading the wrong
   ///                                                                                                                                                           history when moving nodes between servers we require the node identifier. This is only a safety feature.
-  Progress readProgress(byte nodeIdentifier);
+  Progress readProgress(short nodeIdentifier);
 
   /// Save a value into the log.
   /// Logically this method is storing `accept(S,N,V)` so it needs to store the values `{N,V}` at log slot `S`

trex-lib/src/main/java/com/github/trex_paxos/Message.java

@@ -2,5 +2,5 @@
 
 public interface Message {    
     /// @return the node in the cluster that sent this message.
-  byte from();
+    short from();
 }

trex-lib/src/main/java/com/github/trex_paxos/PaxosService.java

@@ -90,7 +90,7 @@ public PaxosService(TrexEngine engine,
   }
 
   /// Shorthand to get the node id which must be unique in the paxos cluster. It is th responsibility of the cluster owner to ensure that it is unique.
-  public byte nodeId() {
+  public short nodeId() {
     return engine.trexNode.nodeIdentifier();
   }
 

trex-lib/src/main/java/com/github/trex_paxos/Pickle.java

@@ -38,7 +38,7 @@ public static byte[] writeProgress(Progress progress) throws IOException {
     }
 
     public static void write(Progress progress, DataOutputStream dos) throws IOException {
-        dos.writeByte(progress.nodeIdentifier());
+        dos.writeShort(progress.nodeIdentifier());
         write(progress.highestPromised(), dos);
         dos.writeLong(progress.highestFixedIndex());
     }
@@ -51,7 +51,7 @@ public static Progress readProgress(byte[] pickled) throws IOException {
     }
 
     private static Progress readProgress(DataInputStream dis) throws IOException {
-        return new Progress(dis.readByte(), readBallotNumber(dis), dis.readLong());
+        return new Progress(dis.readShort(), readBallotNumber(dis), dis.readLong());
     }
 
     public static byte[] write(BallotNumber n) throws IOException {
@@ -64,7 +64,7 @@ public static byte[] write(BallotNumber n) throws IOException {
 
     public static void write(BallotNumber n, DataOutputStream dataOutputStream) throws IOException {
         dataOutputStream.writeInt(n.counter());
-        dataOutputStream.writeByte(n.nodeIdentifier());
+        dataOutputStream.writeShort(n.nodeIdentifier());
     }
 
     public static BallotNumber readBallotNumber(byte[] pickled) throws IOException {
@@ -75,18 +75,18 @@ public static BallotNumber readBallotNumber(byte[] pickled) throws IOException {
     }
 
     public static BallotNumber readBallotNumber(DataInputStream dataInputStream) throws IOException {
-        return new BallotNumber(dataInputStream.readInt(), dataInputStream.readByte());
+        return new BallotNumber(dataInputStream.readInt(), dataInputStream.readShort());
     }
 
     public static void write(Accept m, DataOutputStream dataStream) throws IOException {
-        dataStream.writeByte(m.from());
+        dataStream.writeShort(m.from());
         dataStream.writeLong(m.slot());
         write(m.number(), dataStream);
         write(m.command(), dataStream);
     }
 
     public static Accept readAccept(DataInputStream dataInputStream) throws IOException {
-        final byte from = dataInputStream.readByte();
+        final short from = dataInputStream.readShort();
         final long logIndex = dataInputStream.readLong();
         final BallotNumber number = readBallotNumber(dataInputStream);
         final var command = readCommand(dataInputStream);

trex-lib/src/main/java/com/github/trex_paxos/Progress.java

@@ -24,7 +24,7 @@
  * @param highestFixedIndex The highest log index that has been learnt to have been fixed and so not fixed.
  */
 public record Progress(
-    byte nodeIdentifier,
+  short nodeIdentifier,
     BallotNumber highestPromised,
     long highestFixedIndex
 ) {
@@ -34,7 +34,7 @@ public record Progress(
    *
    * @param nodeIdentifier The current node identifier.
    */
-  public Progress(byte nodeIdentifier) {
+  public Progress(short nodeIdentifier) {
     this(nodeIdentifier, BallotNumber.MIN, 0);
   }
 

trex-lib/src/main/java/com/github/trex_paxos/TrexNode.java

@@ -79,7 +79,7 @@ public boolean isCrashed() {
   /// @param nodeIdentifier The unique node identifier. This must be unique across the cluster and across enough time for prior messages to have been forgotten.
   /// @param quorumStrategy The quorum strategy that may be a simple majority, else things like FPaxos or UPaxos
   /// @param journal        The durable storage and durable log. This must be pre-initialised.
-  public TrexNode(Level logAtLevel, byte nodeIdentifier, QuorumStrategy quorumStrategy, Journal journal) {
+  public TrexNode(Level logAtLevel, short nodeIdentifier, QuorumStrategy quorumStrategy, Journal journal) {
     this.nodeIdentifier = nodeIdentifier;
     this.journal = journal;
     this.quorumStrategy = quorumStrategy;
@@ -92,7 +92,7 @@ public TrexNode(Level logAtLevel, byte nodeIdentifier, QuorumStrategy quorumStra
   }
 
   /// The current node identifier. This must be globally unique in the cluster.
-  final byte nodeIdentifier;
+  final short nodeIdentifier;
 
   /// The durable storage and durable log.
   final Journal journal;
@@ -108,7 +108,7 @@ public TrexNode(Level logAtLevel, byte nodeIdentifier, QuorumStrategy quorumStra
   Progress progress;
 
   /// During a recovery we will track all the slots that we are probing to find the highest accepted operationBytes.
-  final NavigableMap<Long, Map<Byte, PrepareResponse>> prepareResponsesByLogIndex = new TreeMap<>();
+  final NavigableMap<Long, Map<Short, PrepareResponse>> prepareResponsesByLogIndex = new TreeMap<>();
 
   /// When leading we will track the responses to a stream of accept messages.
   final NavigableMap<Long, AcceptVotes> acceptVotesByLogIndex = new TreeMap<>();
@@ -195,6 +195,7 @@ private void algorithm(TrexMessage input,
       return;
     }
     switch (input) {
+
       case Accept accept -> {
         final var number = accept.slotTerm().number();
         final var logIndex = accept.slotTerm().logIndex();
@@ -368,6 +369,12 @@ case CatchupResponse(_, _, final var catchup) -> {
           journal.writeProgress(progress);
         }
       }
+      default -> {
+        // this is unreachable but on refactor to SHORT the compiler complaines FIXME
+        LOGGER.severe("Unknown message type: " + input);
+        throw new IllegalArgumentException("Unknown message type: " + input);
+      }
+
     }
   }
 
@@ -612,7 +619,7 @@ public long highestFixed() {
     return progress.highestFixedIndex();
   }
 
-  public byte nodeIdentifier() {
+  public short nodeIdentifier() {
     return nodeIdentifier;
   }
 
@@ -703,7 +710,7 @@ protected void setRole(TrexRole role) {
   }
 
   private void processPrepareResponse(PrepareResponse prepareResponse, List<TrexMessage> messages) {
-    final byte from = prepareResponse.from();
+    final var from = prepareResponse.from();
     final long logIndex = prepareResponse.vote().logIndex();
     final var votes = prepareResponsesByLogIndex.computeIfAbsent(logIndex, _ -> new HashMap<>());
     votes.put(from, prepareResponse);
@@ -794,7 +801,7 @@ public Progress progress() {
   /**
    * A record of the votes received by a node from other cluster members.
    */
-  public record AcceptVotes(SlotTerm accept, Map<Byte, AcceptResponse> responses, boolean chosen) {
+  public record AcceptVotes(SlotTerm accept, Map<Short, AcceptResponse> responses, boolean chosen) {
     public AcceptVotes(SlotTerm slotTerm) {
       this(slotTerm, new HashMap<>(), false);
     }

trex-lib/src/main/java/com/github/trex_paxos/Value.java

@@ -17,7 +17,7 @@
 
 import java.util.UUID;
 
-public record Value(byte from, UUID uuid, byte[] bytes) implements Message {
+public record Value(short from, UUID uuid, byte[] bytes) implements Message {
     public Value {
         if (uuid == null) {
             throw new IllegalArgumentException("uuid cannot be null");

trex-lib/src/main/java/com/github/trex_paxos/msg/Accept.java

@@ -24,11 +24,11 @@
 /// @param from see {@link TrexMessage}
 /// @param slotTerm  This is the `{S,N}` that identifies the fixed `V`.
 /// @param command  The command to be accepted by the acceptor. This may be a NOOP or a client command.
-public record Accept(byte from,
+public record Accept(short from,
                      SlotTerm slotTerm,
                      AbstractCommand command) implements TrexMessage, BroadcastMessage, PaxosMessage {
 
-  public Accept(byte from, long logIndex, BallotNumber number, AbstractCommand command) {
+  public Accept(short from, long logIndex, BallotNumber number, AbstractCommand command) {
     this(from, new SlotTerm(logIndex, number), command);
 
   }

trex-lib/src/main/java/com/github/trex_paxos/msg/AcceptResponse.java

@@ -24,16 +24,16 @@
 /// @param to                    see {@link DirectMessage}
 /// @param vote                  whether wre have voted for or voted against the Prepare message based on our past promises.
 /// @param highestFixedIndex additional information about the highest accepted index so that a leader will abdicate if it is behind.
-public record AcceptResponse(byte from,
-                             byte to,
+public record AcceptResponse(short from,
+                              short to,
                              Vote vote,
                              long highestFixedIndex
 ) implements TrexMessage, DirectMessage, LearningMessage {
   public record Vote(
       // spookily intellij says there are no usages of this field, but if I remove it everything breaks
-      byte from,
+      short from,
       // spookily intellij says there are no usages of this field, but if I remove it everything breaks
-      byte to,
+      short to,
       long logIndex,
       boolean vote
   ) {

trex-lib/src/main/java/com/github/trex_paxos/msg/Catchup.java

@@ -24,11 +24,10 @@
 /// @param to                   see {@link DirectMessage}
 /// @param highestFixedIndex the highest index that the replica has fixed.
 /// @param highestPromised      the highest ballot number that the replica has promised.
-public record Catchup(byte from,
-                      byte to,
-                      long highestFixedIndex,
-                      BallotNumber highestPromised
-) implements DirectMessage, TrexMessage {
+public record Catchup(short from,
+    short to,
+    long highestFixedIndex,
+    BallotNumber highestPromised) implements DirectMessage, TrexMessage {
 
   @Override
   public String toString() {

trex-lib/src/main/java/com/github/trex_paxos/msg/CatchupResponse.java

@@ -22,8 +22,8 @@
 /// @param from                 see {@link TrexMessage}
 /// @param to                   see {@link DirectMessage}
 /// @param accepts              the list of fixed accepts above the slot index requested.
-public record CatchupResponse(byte from,
-                              byte to,
+public record CatchupResponse(short from,
+                                short to,
                               List<Accept> accepts
 ) implements TrexMessage, DirectMessage, LearningMessage {
 }

trex-lib/src/main/java/com/github/trex_paxos/msg/DirectMessage.java

@@ -18,5 +18,5 @@
 public sealed interface DirectMessage extends TrexMessage 
 permits AcceptResponse, Catchup, CatchupResponse, PrepareResponse {
   /// @return the node in the cluster that this message is intended for.
-  byte to();
+  short to();
 }

trex-lib/src/main/java/com/github/trex_paxos/msg/Fixed.java

@@ -25,10 +25,10 @@
 /// @param from          see {@link TrexMessage}
 /// @param slotTerm  This is the `{S,N}` that identifies the fixed `V`. `
 public record Fixed(
-    byte from,
+  short from,
     SlotTerm slotTerm
 ) implements TrexMessage, BroadcastMessage, LearningMessage {
-  public Fixed(byte from, long logIndex, BallotNumber number) {
+  public Fixed(short from, long logIndex, BallotNumber number) {
     this(from, new SlotTerm(logIndex, number));
   }
 

trex-lib/src/main/java/com/github/trex_paxos/msg/Prepare.java

@@ -23,10 +23,10 @@
 /// @param from     The node identifier of the proposer used to route the message and self-accept.
 /// @param slotTerm  This is the `{S,N}` where a successful leader will select the highest `V`.
 public record Prepare(
-    byte from,
+  short from,
     SlotTerm slotTerm
 ) implements TrexMessage, BroadcastMessage, PaxosMessage {
-  public Prepare(byte from, long logIndex, BallotNumber number) {
+  public Prepare(short from, long logIndex, BallotNumber number) {
     this(from, new SlotTerm(logIndex, number));
   }
 

trex-lib/src/main/java/com/github/trex_paxos/msg/PrepareResponse.java

@@ -28,17 +28,17 @@
 /// @param journaledAccept      the highest unfixed log entry if any.
 /// @param highestAcceptedIndex additional information about the highest accepted index so that a leader can learn of more slots that it needs to recover.
 public record PrepareResponse(
-    byte from,
-    byte to,
+  short from,
+  short to,
     Vote vote,
     Optional<Accept> journaledAccept,
     long highestAcceptedIndex
 ) implements TrexMessage, DirectMessage {
   public record Vote(
       // spookily intellij says there are no usages of this field, but if I remove it everything breaks
-      byte from,
+      short from,
       // spookily intellij says there are no usages of this field, but if I remove it everything breaks
-      byte to,
+      short to,
       long logIndex,
       boolean vote,
       BallotNumber number

trex-lib/src/main/java/com/github/trex_paxos/msg/TrexMessage.java

@@ -28,6 +28,6 @@ public sealed interface TrexMessage extends Message permits
     Prepare,
     PrepareResponse  {
   /// @return the node in the cluster that sent this message.
-  byte from();
+  short from();
 }
 

trex-lib/src/test/java/com/github/trex_paxos/AcceptPropertyTests.java

@@ -22,13 +22,13 @@ record TestCase(
   @Property(generation = GenerationMode.EXHAUSTIVE)
   void acceptTests(@ForAll("testCases") TestCase testCase) {
     // Set up the identifier of the node under test
-    final var thisNodeId = (byte) 2;
+    final var thisNodeId = (short) 2;
 
     // Set up the identifier of the other node relative to the node under test
     final var otherNodeId = switch (testCase.nodeIdentifierRelation) {
-      case LESS -> (byte) (thisNodeId - 1);
+      case LESS -> (short) (thisNodeId - 1);
       case EQUAL -> thisNodeId;
-      case GREATER -> (byte) (thisNodeId + 1);
+      case GREATER -> (short) (thisNodeId + 1);
     };
 
     // Setup ballot number of the node under test

trex-lib/src/test/java/com/github/trex_paxos/AcceptResponsePropertyTests.java

@@ -26,12 +26,12 @@ record TestCase(
 
   @Property(generation = GenerationMode.EXHAUSTIVE)
   void acceptResponseTests(@ForAll("testCases") TestCase testCase) {
-    final var thisNodeId = (byte) 2;
+    final var thisNodeId = (short) 2;
 
     final var otherNodeId = switch (testCase.nodeIdentifierRelation) {
-      case LESS -> (byte) (thisNodeId - 1);
+      case LESS -> (short) (thisNodeId - 1);
       case EQUAL -> thisNodeId;
-      case GREATER -> (byte) (thisNodeId + 1);
+      case GREATER -> (short) (thisNodeId + 1);
     };
 
     final var thisCounter = 100;
@@ -103,7 +103,7 @@ record CreatedData(Accept accept, AcceptVotes votes) {
       ///  Set up an `accept` and `acceptVotes` for a given slot
       private CreatedData createAcceptVotes(long s) {
         final var a = new Accept(thisNodeId, s, thisPromise, NoOperation.NOOP);
-        final Map<Byte, AcceptResponse> responses = new TreeMap<>();
+        final Map<Short, AcceptResponse> responses = new TreeMap<>();
         responses.put(thisNodeId, new AcceptResponse(thisNodeId, thisNodeId,
             new AcceptResponse.Vote(thisNodeId, thisNodeId, s, thisVote), s));
         AcceptVotes votes = new AcceptVotes(a.slotTerm(), responses, false);