feat: operator majority logic

Agoric · Dec 17, 2024 · 0a69684 · 0a69684
1 parent 041cf83
commit 0a69684
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Showing 2 changed files with 35 additions and 22 deletions.
diff --git a/packages/fast-usdc/src/exos/transaction-feed.js b/packages/fast-usdc/src/exos/transaction-feed.js
@@ -124,7 +124,7 @@ export const prepareTransactionFeedKit = (zone, zcf) => {
          * @param {string} operatorId
          */
         attest(evidence, operatorId) {
-          const { pending } = this.state;
+          const { operators, pending } = this.state;
           trace('submitEvidence', operatorId, evidence);
 
           // TODO validate that it's a valid for Fast USDC before accepting
@@ -146,18 +146,32 @@ export const prepareTransactionFeedKit = (zone, zcf) => {
           const found = [...pending.values()].filter(store =>
             store.has(txHash),
           );
-          // TODO determine the real policy for checking agreement
-          if (found.length < pending.getSize()) {
-            // not all have seen it
+          trace('found these stores with the txHash', found.length);
+          const minAttestations = Math.ceil(operators.getSize() / 2);
+          trace(
+            'transaction',
+            txHash,
+            'has',
+            found.length,
+            'of',
+            minAttestations,
+            'necessary attestations',
+          );
+          if (found.length < minAttestations) {
             return;
           }
 
           // TODO verify that all found deep equal
 
-          // all agree, so remove from pending and publish
-          for (const pendingStore of pending.values()) {
-            pendingStore.delete(txHash);
+          // sufficient agreement, so remove from pending and publish
+          for (const store of found) {
+            store.delete(txHash);
           }
+          trace(
+            'stores with the txHash after delete()',
+            [...pending.values()].filter(store => store.has(txHash)).length,
+          );
+          trace('publishing evidence', evidence);
           publisher.publish(evidence);
         },
       },

diff --git a/packages/fast-usdc/test/exos/transaction-feed.test.ts b/packages/fast-usdc/test/exos/transaction-feed.test.ts
@@ -47,31 +47,30 @@ test('happy aggregation', async t => {
   const evidenceSubscriber = feedKit.public.getEvidenceSubscriber();
 
   const { op1, op2, op3 } = await makeOperators(feedKit);
-  const evidence = MockCctpTxEvidences.AGORIC_PLUS_OSMO();
-  op1.operator.submitEvidence(evidence);
-  op2.operator.submitEvidence(evidence);
-  op3.operator.submitEvidence(evidence);
+  const e1 = MockCctpTxEvidences.AGORIC_PLUS_OSMO();
+  op1.operator.submitEvidence(e1);
+  op2.operator.submitEvidence(e1);
 
+  // Publishes with 2 of 3
   const accepted = await evidenceSubscriber.getUpdateSince(0);
   t.deepEqual(accepted, {
-    value: evidence,
+    value: e1,
     updateCount: 1n,
   });
 
-  // verify that it doesn't publish until three match
-  // once it publishes, it doesn't remember that it already saw these
-  op1.operator.submitEvidence(evidence);
-  op2.operator.submitEvidence(evidence);
-  // but this time the third is different
-  op3.operator.submitEvidence(MockCctpTxEvidences.AGORIC_PLUS_DYDX());
-
+  // Now third operator catches up with same evidence already published
+  op3.operator.submitEvidence(e1);
   t.like(await evidenceSubscriber.getUpdateSince(0), {
-    // Update count is still 1
+    // The confirming evidence doesn't change anything
     updateCount: 1n,
   });
-  op3.operator.submitEvidence(evidence);
+
+  const e2 = MockCctpTxEvidences.AGORIC_PLUS_DYDX();
+  assert(e1.txHash !== e2.txHash);
+  op1.operator.submitEvidence(e2);
   t.like(await evidenceSubscriber.getUpdateSince(0), {
-    updateCount: 2n,
+    // op1 attestation insufficient
+    updateCount: 1n,
   });
 });