feat(SwingSet): Split syscall processing into its own crank

packages/SwingSet/src/kernel/kernel.js

@@ -731,15 +731,8 @@ export default function buildKernel(
 
   const gcMessages = ['dropExports', 'retireExports', 'retireImports'];
 
-  function processSyscallQueue() {
-    while (!kernelKeeper.isSyscallQueueEmpty()) {
-      const syscallMessage = kernelKeeper.getNextSyscallQueueMsg();
-      kernelKeeper.addToRunQueue(syscallMessage);
-    }
-  }
-
   let processQueueRunning;
-  async function processQueueMessage(message) {
+  async function processDeliveryMessage(message) {
     kdebug(`processQ ${JSON.stringify(message)}`);
     kdebug(legibilizeMessage(message));
     if (processQueueRunning) {
@@ -803,7 +796,7 @@ export default function buildKernel(
             // delivered again on the next crank.  If we don't want that, then
             // we need to remove it again.
             // eslint-disable-next-line no-use-before-define
-            getNextMessage();
+            getNextDeliveryMessage();
           }
         }
         // state changes reflecting the termination must also survive, so
@@ -833,6 +826,38 @@ export default function buildKernel(
     return harden(policyInput);
   }
 
+  async function processSyscallMessage(message) {
+    kdebug(`processSyscallQ ${JSON.stringify(message)}`);
+    kdebug(legibilizeMessage(message));
+    if (processQueueRunning) {
+      console.error(`We're currently already running at`, processQueueRunning);
+      assert.fail(X`Kernel reentrancy is forbidden`);
+    }
+    kernelSlog.write({ type: 'crank-start', message });
+    /** @type { PolicyInput } */
+    const policyInput = ['none'];
+    try {
+      processQueueRunning = Error('here');
+
+      kernelKeeper.addToRunQueue(message);
+
+      kernelKeeper.processRefcounts();
+      kernelKeeper.saveStats();
+      const crankNum = kernelKeeper.getCrankNumber();
+      kernelKeeper.incrementCrankNumber();
+      const { crankhash, activityhash } = kernelKeeper.commitCrank();
+      kernelSlog.write({
+        type: 'crank-finish',
+        crankNum,
+        crankhash,
+        activityhash,
+      });
+    } finally {
+      processQueueRunning = undefined;
+    }
+    return harden(policyInput);
+  }
+
   const gcTools = harden({
     WeakRef,
     FinalizationRegistry,
@@ -1118,7 +1143,7 @@ export default function buildKernel(
     kernelKeeper.loadStats();
   }
 
-  function getNextMessage() {
+  function getNextDeliveryMessage() {
     const gcMessage = processNextGCAction(kernelKeeper);
     if (gcMessage) {
       return gcMessage;
@@ -1134,18 +1159,39 @@ export default function buildKernel(
     return undefined;
   }
 
+  function getNextSyscallMessage() {
+    if (!kernelKeeper.isSyscallQueueEmpty()) {
+      return kernelKeeper.getNextSyscallQueueMsg();
+    }
+    return undefined;
+  }
+
+  function maybeProcessNextMessage() {
+    /** @type {Promise<PolicyInput> | undefined} */
+    let resultPromise;
+    let message = getNextSyscallMessage();
+    if (message) {
+      resultPromise = processSyscallMessage(message);
+    } else {
+      message = getNextDeliveryMessage();
+      if (message) {
+        resultPromise = processDeliveryMessage(message);
+      }
+    }
+    return { resultPromise };
+  }
+
   async function step() {
     if (kernelPanic) {
       throw kernelPanic;
     }
     if (!started) {
       throw new Error('must do kernel.start() before step()');
     }
-    processSyscallQueue();
+    const { resultPromise } = maybeProcessNextMessage();
     // process a single message
-    const message = getNextMessage();
-    if (message) {
-      await processQueueMessage(message);
+    if (resultPromise) {
+      await resultPromise;
       if (kernelPanic) {
         throw kernelPanic;
       }
@@ -1174,15 +1220,14 @@ export default function buildKernel(
     }
     let count = 0;
     for (;;) {
-      processSyscallQueue();
-      const message = getNextMessage();
-      if (!message) {
+      const { resultPromise } = maybeProcessNextMessage();
+      if (!resultPromise) {
         break;
       }
       count += 1;
       /** @type { PolicyInput } */
       // eslint-disable-next-line no-await-in-loop
-      const policyInput = await processQueueMessage(message);
+      const policyInput = await resultPromise;
       if (kernelPanic) {
         throw kernelPanic;
       }

packages/SwingSet/test/devices/test-devices.js

@@ -122,7 +122,8 @@ test.serial('d1', async t => {
   await c.run();
 
   c.queueToVatRoot('bootstrap', 'step1', capargs([]));
-  await c.step();
+  await c.step(); // syscall
+  await c.step(); // deliver
   t.deepEqual(c.dump().log, [
     'callNow',
     'invoke 1 2',
@@ -155,10 +156,13 @@ async function test2(t, mode) {
   const c = await makeSwingsetController(hostStorage, {});
   for (let i = 0; i < 5; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat start
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
   }
   c.pinVatRoot('bootstrap');
-  await c.step();
+  await c.step(); // syscall
+  await c.step(); // deliver
   if (mode === '1') {
     t.deepEqual(c.dump().log, ['calling d2.method1', 'method1 hello', 'done']);
   } else if (mode === '2') {
@@ -187,15 +191,17 @@ async function test2(t, mode) {
     ]);
   } else if (mode === '5') {
     t.deepEqual(c.dump().log, ['calling v2.method5', 'called']);
-    await c.step();
+    await c.step(); // syscall
+    await c.step(); // deliver
     t.deepEqual(c.dump().log, [
       'calling v2.method5',
       'called',
       'left5',
       'method5 hello',
       'left5 did d2.method5, got ok',
     ]);
-    await c.step();
+    await c.step(); // syscall
+    await c.step(); // deliver
     t.deepEqual(c.dump().log, [
       'calling v2.method5',
       'called',
@@ -346,11 +352,14 @@ test.serial('liveslots throws when D() gets promise', async t => {
 
   for (let i = 0; i < 4; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat start
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
     // eslint-disable-next-line no-await-in-loop
     await c.step(); // bring out your dead
   }
-  await c.step();
+  await c.step(); // syscall
+  await c.step(); // deliver
   // When liveslots catches an attempt to send a promise into D(), it throws
   // a regular error, which the vat can catch.
   t.deepEqual(c.dump().log, ['sending Promise', 'good: callNow failed']);
@@ -388,11 +397,14 @@ test.serial('syscall.callNow(promise) is vat-fatal', async t => {
   const c = await makeSwingsetController(hostStorage, {});
   for (let i = 0; i < 3; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat start
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
     // eslint-disable-next-line no-await-in-loop
     await c.step(); // bring out your dead
   }
-  await c.step(); // bootstrap, which will fail
+  await c.step(); // syscall
+  await c.step(); // deliver bootstrap, which will fail
   // if the kernel paniced, that c.step() will reject, and the await will throw
   t.deepEqual(c.dump().log, ['sending Promise', 'good: callNow failed']);
   // now check that the vat was terminated: this should throw an exception

packages/SwingSet/test/gc/test-gc-vat.js

@@ -52,9 +52,11 @@ async function dropPresence(t, dropExport) {
   c.queueToVatRoot('bootstrap', 'one', capargs([]));
   if (dropExport) {
     c.queueToVatRoot('bootstrap', 'drop', capargs([]));
+    await c.step(); // syscall
     await c.step(); // message
     await c.step(); // reap
   }
+  await c.step(); // syscall
   await c.step(); // message
   await c.step(); // reap
 

packages/SwingSet/test/run-policy/test-run-policy.js

@@ -67,17 +67,17 @@ async function testCranks(t, mode) {
   let more;
 
   if (mode === 'messages' || mode === 'resolutions') {
-    more = await c.run(crankCounter(7, 0, true));
+    more = await c.run(crankCounter(15, 0, true));
     t.truthy(more, 'vat was supposed to run forever');
-    t.is(elapsedCranks(), 7);
+    t.is(elapsedCranks(), 15);
 
-    more = await c.run(crankCounter(1, 0, true));
+    more = await c.run(crankCounter(2, 0, true));
     t.truthy(more, 'vat was supposed to run forever');
-    t.is(elapsedCranks(), 1);
+    t.is(elapsedCranks(), 2);
 
-    more = await c.run(crankCounter(8, 0, true));
+    more = await c.run(crankCounter(16, 0, true));
     t.truthy(more, 'vat was supposed to run forever');
-    t.is(elapsedCranks(), 8);
+    t.is(elapsedCranks(), 16);
   } else if (mode === 'computrons') {
     // the doMessage cycle has four steps:
     // 1: normal delivery (122k-134k computrons)
@@ -91,7 +91,7 @@ async function testCranks(t, mode) {
     // setting a threshold of 4M, we should finish c.run() just after that
     // extra-compute step.
     await c.run(computronCounter(4_000_000n));
-    t.is(elapsedCranks(), 17);
+    t.is(elapsedCranks(), 35);
     const ckey = `${rightID}.vs.vvs.seqnum`;
     const seqnum = parseInt(hostStorage.kvStore.get(ckey), 10);
     t.is(seqnum, 5);

packages/SwingSet/test/test-controller.js

@@ -119,7 +119,9 @@ test('bootstrap', async t => {
   const c = await buildVatController(config);
   for (let i = 0; i < 5; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat starts
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
   }
   t.deepEqual(c.dump().log, ['bootstrap called']);
 });
@@ -133,7 +135,9 @@ test('XS bootstrap', async t => {
   const c = await buildVatController(config, [], { hostStorage });
   for (let i = 0; i < 5; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat starts
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
   }
   t.deepEqual(c.dump().log, ['bootstrap called']);
   t.is(
@@ -170,7 +174,9 @@ test('static vats are unmetered on XS', async t => {
   );
   for (let i = 0; i < 5; i += 1) {
     // eslint-disable-next-line no-await-in-loop
-    await c.step(); // vat starts
+    await c.step(); // vat start syscall
+    // eslint-disable-next-line no-await-in-loop
+    await c.step(); // vat start deliver
   }
   t.deepEqual(c.dump().log, ['bootstrap called']);
   t.deepEqual(limited, [false, false, false, false]);
@@ -265,9 +271,9 @@ test.serial('bootstrap export', async t => {
     },
   ]);
 
-  // this test was designed before GC, and wants to single-step the kernel,
-  // but doesn't care about the GC action steps, so we use this helper
-  // function
+  // this test was designed before GC and syscall queues, and wants to
+  // single-step the kernel, but doesn't care about the GC action steps,
+  // or the temporary syscall queue, so we use this helper function
   async function stepGC() {
     while (c.dump().gcActions.length) {
       // eslint-disable-next-line no-await-in-loop
@@ -277,6 +283,10 @@ test.serial('bootstrap export', async t => {
       // eslint-disable-next-line no-await-in-loop
       await c.step();
     }
+    while (c.dump().syscallQueue.length) {
+      // eslint-disable-next-line no-await-in-loop
+      await c.step();
+    }
     await c.step(); // the non- GC action
   }