fix: refactor liveSlots so it could provide vat globals

This splits up `makeLiveslots` so that the `buildRootObject` function is
provided later, after it returns. This makes it possible to delay the import
of the vat code until after liveslots has provided globals to put into its
Compartment.

This does not yet provide any globals (the `vatGlobals` which `makeLiveslots`
returns is empty). Nor does it change the vat managers to use the
`vatGlobals` in any way. But these changes should be a lot easier now.

refs #1867

packages/SwingSet/src/kernel/liveSlots.js

@@ -23,27 +23,27 @@ import { insistCapData } from '../capdata';
  *
  * @param {*} syscall  Kernel syscall interface that the vat will have access to
  * @param {*} _state  Object to store and retrieve state; not used // TODO fix wart
- * @param {*} buildRootObject  Function that will create a root object for the new vat
  * @param {*} forVatID  Vat ID label, for use in debug diagostics
  * @param {*} vatPowers
  * @param {*} vatParameters
- * @returns {*} an extended dispatcher object for the new vat
+ * @returns {*} { vatGlobals, dispatch, setBuildRootObject }
+ *
+ * setBuildRootObject should be called, once, with a function that will
+ * create a root object for the new vat The caller provided buildRootObject
+ * function produces and returns the new vat's root object:
+ *
+ *     buildRootObject(vatPowers, vatParameters)
  */
-function build(
-  syscall,
-  _state,
-  buildRootObject,
-  forVatID,
-  vatPowers,
-  vatParameters,
-) {
+function build(syscall, _state, forVatID, vatPowers, vatParameters) {
   const enableLSDebug = false;
   function lsdebug(...args) {
     if (enableLSDebug) {
       console.log(...args);
     }
   }
 
+  let didRoot = false;
+
   const outstandingProxies = new WeakSet();
 
   /**
@@ -342,6 +342,7 @@ function build(
   }
 
   function deliver(target, method, argsdata, result) {
+    assert(didRoot);
     insistCapData(argsdata);
     lsdebug(
       `ls[${forVatID}].dispatch.deliver ${target}.${method} -> ${result}`,
@@ -472,6 +473,7 @@ function build(
   }
 
   function notifyFulfillToData(promiseID, data) {
+    assert(didRoot);
     insistCapData(data);
     lsdebug(
       `ls.dispatch.notifyFulfillToData(${promiseID}, ${data.body}, ${data.slots})`,
@@ -488,6 +490,7 @@ function build(
   }
 
   function notifyFulfillToPresence(promiseID, slot) {
+    assert(didRoot);
     lsdebug(`ls.dispatch.notifyFulfillToPresence(${promiseID}, ${slot})`);
     insistVatType('promise', promiseID);
     // TODO: insist that we do not have decider authority for promiseID
@@ -506,6 +509,7 @@ function build(
   // TODO: when we add notifyForward, guard against cycles
 
   function notifyReject(promiseID, data) {
+    assert(didRoot);
     insistCapData(data);
     lsdebug(
       `ls.dispatch.notifyReject(${promiseID}, ${data.body}, ${data.slots})`,
@@ -532,25 +536,31 @@ function build(
   // vats which use D are in: acorn-eventual-send, cosmic-swingset
   // (bootstrap, bridge, vat-http), swingset
 
-  // here we finally invoke the vat code, and get back the root object
-  const rootObject = buildRootObject(
-    harden({ D, exitVat, exitVatWithFailure, ...vatPowers }),
-    harden(vatParameters),
-  );
-  mustPassByPresence(rootObject);
+  const vatGlobals = harden({}); // for later use: #1846
+
+  function setBuildRootObject(buildRootObject) {
+    assert(!didRoot);
+    didRoot = true;
 
-  const rootSlot = makeVatSlot('object', true, 0);
-  valToSlot.set(rootObject, rootSlot);
-  slotToVal.set(rootSlot, rootObject);
+    // here we finally invoke the vat code, and get back the root object
+    const rootObject = buildRootObject(
+      harden({ D, exitVat, exitVatWithFailure, ...vatPowers }),
+      harden(vatParameters),
+    );
+    mustPassByPresence(rootObject);
+
+    const rootSlot = makeVatSlot('object', true, 0);
+    valToSlot.set(rootObject, rootSlot);
+    slotToVal.set(rootSlot, rootObject);
+  }
 
-  return {
-    m,
+  const dispatch = harden({
     deliver,
-    // subscribe,
     notifyFulfillToData,
     notifyFulfillToPresence,
     notifyReject,
-  };
+  });
+  return harden({ vatGlobals, setBuildRootObject, dispatch, m });
 }
 
 /**
@@ -559,14 +569,14 @@ function build(
  *
  * @param {*} syscall  Kernel syscall interface that the vat will have access to
  * @param {*} state  Object to store and retrieve state
- * @param {*} buildRootObject  Function that will create a root object for the new vat
  * @param {*} forVatID  Vat ID label, for use in debug diagostics
  * @param {*} vatPowers
  * @param {*} vatParameters
- * @returns {*} a dispatcher object for the new vat
+ * @returns {*} { vatGlobals, dispatch, setBuildRootObject }
  *
- * The caller provided buildRootObject function produces and returns the new vat's
- * root object:
+ * setBuildRootObject should be called, once, with a function that will
+ * create a root object for the new vat The caller provided buildRootObject
+ * function produces and returns the new vat's root object:
  *
  *     buildRootObject(vatPowers, vatParameters)
  *
@@ -589,33 +599,18 @@ function build(
 export function makeLiveSlots(
   syscall,
   state,
-  buildRootObject,
   forVatID = 'unknown',
   vatPowers = harden({}),
   vatParameters = harden({}),
 ) {
-  const {
-    deliver,
-    notifyFulfillToData,
-    notifyFulfillToPresence,
-    notifyReject,
-  } = build(
-    syscall,
-    state,
-    buildRootObject,
-    forVatID,
-    { ...vatPowers, getInterfaceOf, Remotable, makeMarshal },
-    vatParameters,
-  );
-  return harden({
-    deliver,
-    notifyFulfillToData,
-    notifyFulfillToPresence,
-    notifyReject,
-  });
+  const allVatPowers = { ...vatPowers, getInterfaceOf, Remotable, makeMarshal };
+  const r = build(syscall, state, forVatID, allVatPowers, vatParameters);
+  const { vatGlobals, dispatch, setBuildRootObject } = r; // omit 'm'
+  return harden({ vatGlobals, dispatch, setBuildRootObject });
 }
 
 // for tests
 export function makeMarshaller(syscall) {
-  return { m: build(syscall, null, _E => harden({})).m };
+  const { m } = build(syscall);
+  return { m };
 }

packages/SwingSet/src/kernel/vatManager/localVatManager.js

@@ -137,14 +137,9 @@ export function makeLocalVatManagerFactory(tools) {
     let dispatch;
     if (typeof vatNS.buildRootObject === 'function') {
       const { buildRootObject } = vatNS;
-      dispatch = makeLiveSlots(
-        syscall,
-        state,
-        buildRootObject,
-        vatID,
-        vatPowers,
-        vatParameters,
-      );
+      const r = makeLiveSlots(syscall, state, vatID, vatPowers, vatParameters);
+      r.setBuildRootObject(buildRootObject);
+      dispatch = r.dispatch;
     } else if (enableSetup) {
       const setup = vatNS.default;
       assert(setup, `vat source bundle lacks (default) setup() function`);

packages/SwingSet/src/kernel/vatManager/nodeWorkerSupervisor.js

@@ -121,14 +121,9 @@ parentPort.on('message', ([type, ...margs]) => {
         makeMarshal,
         testLog,
       };
-      dispatch = makeLiveSlots(
-        syscall,
-        state,
-        vatNS.buildRootObject,
-        vatID,
-        vatPowers,
-        vatParameters,
-      );
+      const r = makeLiveSlots(syscall, state, vatID, vatPowers, vatParameters);
+      r.setBuildRootObject(vatNS.buildRootObject);
+      dispatch = r.dispatch;
       workerLog(`got dispatch:`, Object.keys(dispatch).join(','));
       sendUplink(['dispatchReady']);
     });

packages/SwingSet/src/kernel/vatManager/subprocessSupervisor.js

@@ -142,14 +142,9 @@ fromParent.on('data', data => {
         makeMarshal,
         testLog,
       };
-      dispatch = makeLiveSlots(
-        syscall,
-        state,
-        vatNS.buildRootObject,
-        vatID,
-        vatPowers,
-        vatParameters,
-      );
+      const r = makeLiveSlots(syscall, state, vatID, vatPowers, vatParameters);
+      r.setBuildRootObject(vatNS.buildRootObject);
+      dispatch = r.dispatch;
       workerLog(`got dispatch:`, Object.keys(dispatch).join(','));
       sendUplink(['dispatchReady']);
     });

packages/SwingSet/test/test-liveslots.js

@@ -36,6 +36,12 @@ function buildSyscall() {
   return { log, syscall };
 }
 
+function makeDispatch(syscall, build) {
+  const { setBuildRootObject, dispatch } = makeLiveSlots(syscall, null, 'vatA');
+  setBuildRootObject(build);
+  return dispatch;
+}
+
 test('calls', async t => {
   const { log, syscall } = buildSyscall();
 
@@ -53,7 +59,7 @@ test('calls', async t => {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
   const rootA = 'o+0';
 
@@ -113,7 +119,7 @@ test('liveslots pipelines to syscall.send', async t => {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
   const rootA = 'o+0';
   const x = 'o-5';
@@ -177,7 +183,7 @@ test('liveslots pipeline/non-pipeline calls', async t => {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
 
   t.deepEqual(log, []);
 
@@ -258,7 +264,7 @@ async function doOutboundPromise(t, mode) {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
 
   t.deepEqual(log, []);
 
@@ -371,7 +377,7 @@ async function doResultPromise(t, mode) {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
 
   const slot0arg = { '@qclass': 'slot', index: 0 };

packages/SwingSet/test/test-vpid-liveslots.js

@@ -189,6 +189,12 @@ function resolutionOf(vpid, mode, targets) {
   }
 }
 
+function makeDispatch(syscall, build) {
+  const { setBuildRootObject, dispatch } = makeLiveSlots(syscall, null, 'vatA');
+  setBuildRootObject(build);
+  return dispatch;
+}
+
 async function doVatResolveCase1(t, mode) {
   // case 1
   const { log, syscall } = buildSyscall();
@@ -207,7 +213,7 @@ async function doVatResolveCase1(t, mode) {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
 
   const rootA = 'o+0';
@@ -374,7 +380,7 @@ async function doVatResolveCase23(t, which, mode, stalls) {
       },
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
 
   const rootA = 'o+0';
@@ -605,7 +611,7 @@ async function doVatResolveCase4(t, mode) {
       four() {},
     });
   }
-  const dispatch = makeLiveSlots(syscall, {}, build, 'vatA');
+  const dispatch = makeDispatch(syscall, build);
   t.deepEqual(log, []);
 
   const rootA = 'o+0';