From e81fdcdb39d237ef53ba7d94fe5e26a4c15d4c0d Mon Sep 17 00:00:00 2001
From: Turadg Aleahmad <turadg@agoric.com>
Date: Thu, 12 Dec 2024 18:17:59 -0800
Subject: [PATCH] feat: deleteCompletedTxs

---
 packages/fast-usdc/src/constants.js           |  7 +++-
 packages/fast-usdc/src/exos/status-manager.js | 40 ++++++++++++++++++-
 packages/fast-usdc/test/exos/settler.test.ts  | 10 +++++
 3 files changed, 54 insertions(+), 3 deletions(-)

diff --git a/packages/fast-usdc/src/constants.js b/packages/fast-usdc/src/constants.js
index d341f6c650d..28ab7775db7 100644
--- a/packages/fast-usdc/src/constants.js
+++ b/packages/fast-usdc/src/constants.js
@@ -21,7 +21,12 @@ export const TxStatus = /** @type {const} */ ({
 });
 harden(TxStatus);
 
-// TODO: define valid state transitions
+// According to the state diagram
+export const TerminalTxStatus = {
+  [TxStatus.Forwarded]: true,
+  [TxStatus.ForwardFailed]: true,
+  [TxStatus.Disbursed]: true,
+};
 
 /**
  * Status values for the StatusManager.
diff --git a/packages/fast-usdc/src/exos/status-manager.js b/packages/fast-usdc/src/exos/status-manager.js
index b67185b5a7a..9a3bfd7d8f3 100644
--- a/packages/fast-usdc/src/exos/status-manager.js
+++ b/packages/fast-usdc/src/exos/status-manager.js
@@ -8,7 +8,7 @@ import {
   EvmHashShape,
   PendingTxShape,
 } from '../type-guards.js';
-import { PendingTxStatus, TxStatus } from '../constants.js';
+import { PendingTxStatus, TerminalTxStatus, TxStatus } from '../constants.js';
 
 /**
  * @import {MapStore, SetStore} from '@agoric/store';
@@ -78,11 +78,26 @@ export const prepareStatusManager = (
     valueShape: M.arrayOf(PendingTxShape),
   });
 
-  /** @type {SetStore<EvmHash>} */
+  /**
+   * Transactions seen *ever* by the contract.
+   *
+   * Note that these are stored in IAVL and grow monotonically. At some point in the future we may want to prune them.
+   *
+   * @type {SetStore<EvmHash>}
+   */
   const seenTxs = zone.setStore('SeenTxs', {
     keyShape: M.string(),
   });
 
+  /**
+   * Transactions that have completed, but are still in vstorage.
+   *
+   * @type {SetStore<EvmHash>}
+   */
+  const storedCompletedTxs = zone.setStore('StoredCompletedTxs', {
+    keyShape: M.string(),
+  });
+
   /**
    * @param {CctpTxEvidence['txHash']} hash
    * @param {CctpTxEvidence} evidence
@@ -101,6 +116,13 @@ export const prepareStatusManager = (
     const txnNodeP = E(transactionsNode).makeChildNode(hash);
     // Don't await, just writing to vstorage.
     void E(txnNodeP).setValue(status);
+    if (TerminalTxStatus[status]) {
+      // UNTIL https://github.com/Agoric/agoric-sdk/issues/7405
+      // Queue it for deletion later because if we deleted it now the earlier
+      // writes in this block would be wiped. For now we keep track of what to
+      // delete when we know it'll be another block.
+      storedCompletedTxs.add(hash);
+    }
   };
 
   /**
@@ -158,6 +180,7 @@ export const prepareStatusManager = (
       advanceOutcome: M.call(M.string(), M.nat(), M.boolean()).returns(),
       observe: M.call(CctpTxEvidenceShape).returns(M.undefined()),
       hasBeenObserved: M.call(CctpTxEvidenceShape).returns(M.boolean()),
+      deleteCompletedTxs: M.call().returns(M.undefined()),
       dequeueStatus: M.call(M.string(), M.bigint()).returns(
         M.or(
           {
@@ -223,6 +246,19 @@ export const prepareStatusManager = (
         return seenTxs.has(evidence.txHash);
       },
 
+      // UNTIL https://github.com/Agoric/agoric-sdk/issues/7405
+      deleteCompletedTxs() {
+        for (const txHash of storedCompletedTxs.values()) {
+          // As of now, setValue('') on a non-sequence node will delete it
+          const txNode = E(transactionsNode).makeChildNode(txHash, {
+            sequence: false,
+          });
+          void E(txNode)
+            .setValue('')
+            .then(() => storedCompletedTxs.delete(txHash));
+        }
+      },
+
       /**
        * Remove and return an `ADVANCED` or `OBSERVED` tx waiting to be `SETTLED`.
        *
diff --git a/packages/fast-usdc/test/exos/settler.test.ts b/packages/fast-usdc/test/exos/settler.test.ts
index d82479479c9..9456fb5417a 100644
--- a/packages/fast-usdc/test/exos/settler.test.ts
+++ b/packages/fast-usdc/test/exos/settler.test.ts
@@ -242,6 +242,11 @@ test('happy path: disburse to LPs; StatusManager removes tx', async t => {
     'ADVANCED',
     'DISBURSED',
   ]);
+
+  // Check deletion of DISBURSED transactions
+  statusManager.deleteCompletedTxs();
+  await eventLoopIteration();
+  t.is(storage.data.get(`fun.txns.${cctpTxEvidence.txHash}`), undefined);
 });
 
 test('slow path: forward to EUD; remove pending tx', async t => {
@@ -314,6 +319,11 @@ test('slow path: forward to EUD; remove pending tx', async t => {
     'OBSERVED',
     'FORWARDED',
   ]);
+
+  // Check deletion of FORWARDED transactions
+  statusManager.deleteCompletedTxs();
+  await eventLoopIteration();
+  t.is(storage.data.get(`fun.txns.${cctpTxEvidence.txHash}`), undefined);
 });
 
 test('Settlement for unknown transaction', async t => {