fix: persistently track transcript start position for transcript cont…

…inuity across upgrades

Closes #3293

packages/SwingSet/src/kernel/state/kernelKeeper.js

@@ -71,6 +71,7 @@ const enableKernelGC = true;
 //   $vatSlot is one of: o+$NN/o-$NN/p+$NN/p-$NN/d+$NN/d-$NN
 // v$NN.c.$vatSlot = $kernelSlot = ko$NN/kp$NN/kd$NN
 // v$NN.nextDeliveryNum = $NN
+// v$NN.t.startPosition = $NN
 // v$NN.t.endPosition = $NN
 // v$NN.vs.$key = string
 // v$NN.meter = m$NN // XXX does this exist?

packages/SwingSet/src/kernel/state/vatKeeper.js

@@ -35,6 +35,10 @@ export function initializeVatState(kvStore, streamStore, vatID) {
   kvStore.set(`${vatID}.p.nextID`, `${FIRST_PROMISE_ID}`);
   kvStore.set(`${vatID}.d.nextID`, `${FIRST_DEVICE_ID}`);
   kvStore.set(`${vatID}.nextDeliveryNum`, `0`);
+  kvStore.set(
+    `${vatID}.t.startPosition`,
+    `${JSON.stringify(streamStore.STREAM_START)}`,
+  );
   kvStore.set(
     `${vatID}.t.endPosition`,
     `${JSON.stringify(streamStore.STREAM_START)}`,
@@ -454,11 +458,14 @@ export function makeVatKeeper(
    *
    * @yields { TranscriptEntry } a stream of transcript entries
    */
-  function* getTranscript(startPos = streamStore.STREAM_START) {
+  function* getTranscript(startPos) {
+    if (startPos === undefined) {
+      startPos = JSON.parse(getRequired(`${vatID}.t.startPosition`));
+    }
     const endPos = JSON.parse(getRequired(`${vatID}.t.endPosition`));
     for (const entry of streamStore.readStream(
       transcriptStream,
-      startPos,
+      /** @type { StreamPosition } */ (startPos),
       endPos,
     )) {
       yield /** @type { TranscriptEntry } */ (JSON.parse(entry));
@@ -582,7 +589,6 @@ export function makeVatKeeper(
 
   function removeSnapshotAndTranscript() {
     const skey = `local.${vatID}.lastSnapshot`;
-    const epkey = `${vatID}.t.endPosition`;
     if (snapStore) {
       const notation = kvStore.get(skey);
       if (notation) {
@@ -596,9 +602,9 @@ export function makeVatKeeper(
       }
     }
     // TODO: same rollback concern
-    // TODO: streamStore.deleteStream(transcriptStream);
-    const newStart = streamStore.STREAM_START;
-    kvStore.set(epkey, `${JSON.stringify(newStart)}`);
+
+    const endPos = getRequired(`${vatID}.t.endPosition`);
+    kvStore.set(`${vatID}.t.startPosition`, endPos);
   }
 
   function vatStats() {
@@ -610,9 +616,13 @@ export function makeVatKeeper(
     const objectCount = getCount(`${vatID}.o.nextID`, FIRST_OBJECT_ID);
     const promiseCount = getCount(`${vatID}.p.nextID`, FIRST_PROMISE_ID);
     const deviceCount = getCount(`${vatID}.d.nextID`, FIRST_DEVICE_ID);
-    const transcriptCount = JSON.parse(
+    const startCount = JSON.parse(
+      getRequired(`${vatID}.t.startPosition`),
+    ).itemCount;
+    const endCount = JSON.parse(
       getRequired(`${vatID}.t.endPosition`),
     ).itemCount;
+    const transcriptCount = endCount - startCount;
 
     // TODO: Fix the downstream JSON.stringify to allow the counts to be BigInts
     return harden({

packages/SwingSet/test/upgrade/bootstrap-upgrade-replay.js

@@ -0,0 +1,38 @@
+import { E } from '@endo/eventual-send';
+import { Far } from '@endo/marshal';
+
+export function buildRootObject() {
+  let vatAdmin;
+  let uptonRoot;
+  let uptonAdmin;
+
+  return Far('root', {
+    async bootstrap(vats, devices) {
+      vatAdmin = await E(vats.vatAdmin).createVatAdminService(devices.vatAdmin);
+    },
+
+    async buildV1() {
+      // build Upton, the upgrading vat
+      const bcap = await E(vatAdmin).getNamedBundleCap('upton');
+      const vatParameters = { version: 'v1' };
+      const options = { vatParameters };
+      const res = await E(vatAdmin).createVat(bcap, options);
+      uptonRoot = res.root;
+      uptonAdmin = res.adminNode;
+      return E(uptonRoot).phase1();
+    },
+
+    async upgradeV2() {
+      // upgrade Upton to version 2
+      const bcap = await E(vatAdmin).getNamedBundleCap('upton');
+      const vatParameters = { version: 'v2' };
+      await E(uptonAdmin).upgrade(bcap, vatParameters);
+      return E(uptonRoot).phase2();
+    },
+
+    async checkReplay() {
+      // ask Upton to do something after a restart
+      return E(uptonRoot).checkReplay();
+    },
+  });
+}

packages/SwingSet/test/upgrade/test-upgrade-replay.js

@@ -0,0 +1,84 @@
+// eslint-disable-next-line import/order
+import { test } from '../../tools/prepare-test-env-ava.js';
+
+import { assert } from '@agoric/assert';
+import { getAllState, setAllState } from '@agoric/swing-store';
+import { provideHostStorage } from '../../src/controller/hostStorage.js';
+import {
+  buildKernelBundles,
+  initializeSwingset,
+  makeSwingsetController,
+} from '../../src/index.js';
+import { capargs } from '../util.js';
+
+function bfile(name) {
+  return new URL(name, import.meta.url).pathname;
+}
+
+function copy(data) {
+  return JSON.parse(JSON.stringify(data));
+}
+
+async function run(c, name, args = []) {
+  assert(Array.isArray(args));
+  const kpid = c.queueToVatRoot('bootstrap', name, capargs(args));
+  await c.run();
+  const status = c.kpStatus(kpid);
+  const capdata = c.kpResolution(kpid);
+  return [status, capdata];
+}
+
+test.before(async t => {
+  const kernelBundles = await buildKernelBundles();
+  t.context.data = { kernelBundles };
+});
+
+test('replay after upgrade', async t => {
+  const config = {
+    bootstrap: 'bootstrap',
+    vats: {
+      bootstrap: { sourceSpec: bfile('bootstrap-upgrade-replay.js') },
+    },
+    bundles: {
+      upton: { sourceSpec: bfile('vat-upton-replay.js') },
+    },
+  };
+
+  const hostStorage1 = provideHostStorage();
+  {
+    await initializeSwingset(copy(config), [], hostStorage1, {
+      kernelBundles: t.context.data.kernelBundles,
+    });
+    const c1 = await makeSwingsetController(hostStorage1);
+    c1.pinVatRoot('bootstrap');
+    await c1.run();
+
+    // create initial version
+    const [v1status, v1data] = await run(c1, 'buildV1');
+    t.is(v1status, 'fulfilled');
+    t.deepEqual(v1data, capargs(1));
+
+    // now perform the upgrade
+    const [v2status, v2data] = await run(c1, 'upgradeV2');
+    t.is(v2status, 'fulfilled');
+    // upgrade restart loses RAM state, hence adding 20 yields 20 rather than 21
+    t.deepEqual(v2data, capargs(20));
+  }
+
+  // copy the store just to be sure
+  const state1 = getAllState(hostStorage1);
+  const hostStorage2 = provideHostStorage();
+  setAllState(hostStorage2, state1);
+  {
+    const c2 = await makeSwingsetController(hostStorage2);
+    c2.pinVatRoot('bootstrap');
+    await c2.run();
+
+    // do something after replay that says we're still alive
+    const [rstatus, rdata] = await run(c2, 'checkReplay');
+    t.is(rstatus, 'fulfilled');
+
+    // replay retains RAM state of post-upgrade vat, hence adding 300 yields 320
+    t.deepEqual(rdata, capargs(320));
+  }
+});

packages/SwingSet/test/upgrade/vat-upton-replay.js

@@ -0,0 +1,22 @@
+import { Far } from '@endo/marshal';
+
+export function buildRootObject() {
+  let counter = 0;
+
+  return Far('root', {
+    phase1() {
+      counter += 1;
+      return counter;
+    },
+
+    phase2() {
+      counter += 20;
+      return counter;
+    },
+
+    checkReplay() {
+      counter += 300;
+      return counter;
+    },
+  });
+}

packages/SwingSet/test/vat-admin/terminate/test-terminate.js

@@ -213,7 +213,7 @@ test('dead vat state removed', async t => {
   const kvStore = hostStorage.kvStore;
   t.is(kvStore.get('vat.dynamicIDs'), '["v6"]');
   t.is(kvStore.get('ko26.owner'), 'v6');
-  t.is(Array.from(kvStore.getKeys('v6.', 'v6/')).length, 32);
+  t.is(Array.from(kvStore.getKeys('v6.', 'v6/')).length, 33);
 
   controller.queueToVatRoot('bootstrap', 'phase2', capargs([]));
   await controller.run();