lamport timestamp remains close to current time

packages/sdk/src/reliable_channel/reliable_channel.spec.ts

@@ -721,7 +721,7 @@ describe("Reliable Channel", () => {
         "differentChannel",
         senderId,
         [],
-        1,
+        1n,
         undefined,
         utf8ToBytes("different channel")
       );
@@ -731,7 +731,7 @@ describe("Reliable Channel", () => {
         channelId,
         senderId,
         [],
-        2,
+        2n,
         undefined,
         undefined
       );
@@ -741,7 +741,7 @@ describe("Reliable Channel", () => {
         channelId,
         senderId,
         [],
-        3,
+        3n,
         undefined,
         utf8ToBytes("after sync")
       );
@@ -824,7 +824,7 @@ describe("Reliable Channel", () => {
         channelId,
         senderId,
         [{ messageId: "previous-msg-id" }],
-        1,
+        1n,
         undefined,
         utf8ToBytes("content message")
       );
@@ -834,7 +834,7 @@ describe("Reliable Channel", () => {
         channelId,
         senderId,
         [],
-        2,
+        2n,
         undefined,
         utf8ToBytes("after content")
       );
@@ -905,7 +905,7 @@ describe("Reliable Channel", () => {
         "differentChannel1",
         senderId,
         [],
-        1,
+        1n,
         undefined,
         utf8ToBytes("different 1")
       );
@@ -915,7 +915,7 @@ describe("Reliable Channel", () => {
         "differentChannel2",
         senderId,
         [],
-        2,
+        2n,
         undefined,
         utf8ToBytes("different 2")
       );
@@ -925,7 +925,7 @@ describe("Reliable Channel", () => {
         "differentChannel3",
         senderId,
         [],
-        3,
+        3n,
         undefined,
         utf8ToBytes("different 3")
       );
@@ -1041,7 +1041,7 @@ describe("Reliable Channel", () => {
         "differentChannel",
         "sender",
         [],
-        1,
+        1n,
         undefined,
         utf8ToBytes("content")
       );
@@ -1060,7 +1060,7 @@ describe("Reliable Channel", () => {
         "testChannel",
         "sender",
         [],
-        1,
+        1n,
         undefined,
         undefined
       );
@@ -1079,7 +1079,7 @@ describe("Reliable Channel", () => {
         "testChannel",
         "sender",
         [],
-        1,
+        1n,
         undefined,
         utf8ToBytes("content")
       );
@@ -1098,7 +1098,7 @@ describe("Reliable Channel", () => {
         "testChannel",
         "sender",
         [{ messageId: "previous-msg-id" }],
-        1,
+        1n,
         undefined,
         utf8ToBytes("content")
       );
@@ -1117,7 +1117,7 @@ describe("Reliable Channel", () => {
         "testChannel",
         "sender",
         [{ messageId: "previous-msg-id" }],
-        1,
+        1n,
         undefined,
         undefined
       );

packages/sds/src/message_channel/lamport_timestamp.spec.ts

@@ -0,0 +1,56 @@
+import { expect } from "chai";
+
+import { lamportTimestampIncrement } from "./message_channel.js";
+
+describe("lamportTimestampIncrement", () => {
+  it("should increment timestamp by 1 when current time is not greater", () => {
+    const futureTimestamp = BigInt(Date.now()) + 1000n;
+    const result = lamportTimestampIncrement(futureTimestamp);
+    expect(result).to.equal(futureTimestamp + 1n);
+  });
+
+  it("should use current time when it's greater than incremented timestamp", () => {
+    const pastTimestamp = BigInt(Date.now()) - 1000n;
+    const result = lamportTimestampIncrement(pastTimestamp);
+    const now = BigInt(Date.now());
+    // Result should be at least as large as now (within small tolerance for test execution time)
+    expect(result >= now - 10n).to.be.true;
+    expect(result <= now + 10n).to.be.true;
+  });
+
+  it("should handle timestamp equal to current time", () => {
+    const currentTimestamp = BigInt(Date.now());
+    const result = lamportTimestampIncrement(currentTimestamp);
+    // Should increment by 1 since now is likely not greater than current + 1
+    expect(result >= currentTimestamp + 1n).to.be.true;
+  });
+
+  it("should ensure monotonic increase", () => {
+    let timestamp = BigInt(Date.now()) + 5000n;
+    const results: bigint[] = [];
+
+    for (let i = 0; i < 5; i++) {
+      timestamp = lamportTimestampIncrement(timestamp);
+      results.push(timestamp);
+    }
+
+    // Verify all timestamps are strictly increasing
+    for (let i = 1; i < results.length; i++) {
+      expect(results[i] > results[i - 1]).to.be.true;
+    }
+  });
+
+  it("should handle very large timestamps", () => {
+    const largeTimestamp = BigInt(Number.MAX_SAFE_INTEGER) * 1000n;
+    const result = lamportTimestampIncrement(largeTimestamp);
+    expect(result).to.equal(largeTimestamp + 1n);
+  });
+
+  it("should jump to current time when timestamp is far in the past", () => {
+    const veryOldTimestamp = 1000n; // Very old timestamp (1 second after epoch)
+    const result = lamportTimestampIncrement(veryOldTimestamp);
+    const now = BigInt(Date.now());
+    expect(result >= now - 10n).to.be.true;
+    expect(result <= now + 10n).to.be.true;
+  });
+});

packages/sds/src/message_channel/message_channel.ts

@@ -95,8 +95,8 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
     super();
     this.channelId = channelId;
     this.senderId = senderId;
-    // Initialize channel lamport timestamp to current time in seconds.
-    this.lamportTimestamp = BigInt(Math.floor(Date.now() / 1000));
+    // Initialize channel lamport timestamp to current time in milliseconds.
+    this.lamportTimestamp = BigInt(Date.now());
     this.filter = new DefaultBloomFilter(DEFAULT_BLOOM_FILTER_OPTIONS);
     this.outgoingBuffer = [];
     this.possibleAcks = new Map();
@@ -368,7 +368,7 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
   public async pushOutgoingSyncMessage(
     callback?: (message: SyncMessage) => Promise<boolean>
   ): Promise<boolean> {
-    this.lamportTimestamp = this.lamportTimestamp + 1n;
+    this.lamportTimestamp = lamportTimestampIncrement(this.lamportTimestamp);
     const message = new SyncMessage(
       // does not need to be secure randomness
       `sync-${Math.random().toString(36).substring(2)}`,
@@ -525,7 +525,7 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
       retrievalHint?: Uint8Array;
     }>
   ): Promise<void> {
-    this.lamportTimestamp = this.lamportTimestamp + 1n;
+    this.lamportTimestamp = lamportTimestampIncrement(this.lamportTimestamp);
 
     const messageId = MessageChannel.getMessageId(payload);
 
@@ -723,3 +723,12 @@ export class MessageChannel extends TypedEventEmitter<MessageChannelEvents> {
     });
   }
 }
+
+export function lamportTimestampIncrement(lamportTimestamp: bigint): bigint {
+  const now = BigInt(Date.now());
+  lamportTimestamp++;
+  if (now > lamportTimestamp) {
+    return now;
+  }
+  return lamportTimestamp;
+}