remove in-RAM list of all collections

This removes `deleteAllVirtualCollections`, and the in-RAM
`allCollectionObjIDs` Set of all collectionIDs which supported
it. Once upon a time, `stopVat` called `deleteAllVirtualCollections`
to delete the vatstore data for all non-durable virtual
collections. We removed responsibility for deleting virtual data from
the vat (and stopped calling `stopVat` altogether) in the interests of
reducing upgrade risk, and improving upgrade performance, despite the
fact that this will cause a DB storage leak during upgrade (we figure
we can find a way to fix that later, and disk is cheap).

Now that `deleteAllVirtualCollections` is gone, we don't need to spend
the RAM on each collection, which violated our high-cardinality design
rules anyways.

refs #5058

packages/swingset-liveslots/src/collectionManager.js

@@ -58,12 +58,6 @@ export function makeCollectionManager(
   unserialize,
   assertAcceptableSyscallCapdataSize,
 ) {
-  // TODO(#5058): we hold a list of all collections (both virtual and
-  // durable) in RAM, so we can delete the virtual ones during
-  // stopVat(), and tolerate subsequent GC-triggered duplication
-  // deletion without crashing. This needs to move to the DB to avoid
-  // the RAM consumption of a large number of collections.
-  const allCollectionObjIDs = new Set();
   const storeKindIDToName = new Map();
 
   const storeKindInfo = {
@@ -656,9 +650,6 @@ export function makeCollectionManager(
   }
 
   function deleteCollection(vobjID) {
-    if (!allCollectionObjIDs.has(vobjID)) {
-      return false; // already deleted
-    }
     const { id, subid } = parseVatSlot(vobjID);
     const kindName = storeKindIDToName.get(`${id}`);
     const collectionID = `${subid}`;
@@ -668,7 +659,6 @@ export function makeCollectionManager(
       collectionID,
       kindName,
     );
-    allCollectionObjIDs.delete(vobjID);
 
     const doMoreGC = collection.clearInternal(true);
     for (const dbKey of enumerateKeysWithPrefix(syscall, prefixc(subid, '|'))) {
@@ -677,18 +667,6 @@ export function makeCollectionManager(
     return doMoreGC;
   }
 
-  function deleteAllVirtualCollections() {
-    const vobjIDs = Array.from(allCollectionObjIDs).sort();
-    for (const vobjID of vobjIDs) {
-      const { id } = parseVatSlot(vobjID);
-      const kindName = storeKindIDToName.get(`${id}`);
-      const { durable } = storeKindInfo[kindName];
-      if (!durable) {
-        deleteCollection(vobjID);
-      }
-    }
-  }
-
   function makeCollection(label, kindName, isDurable, keyShape, valueShape) {
     assert.typeof(label, 'string');
     assert(storeKindInfo[kindName]);
@@ -712,7 +690,6 @@ export function makeCollectionManager(
       JSON.stringify(serialize(harden(schemata))),
     );
     syscall.vatstoreSet(prefixc(collectionID, '|label'), label);
-    allCollectionObjIDs.add(vobjID);
 
     return [
       vobjID,
@@ -1023,7 +1000,6 @@ export function makeCollectionManager(
 
   return harden({
     initializeStoreKindInfo,
-    deleteAllVirtualCollections,
     makeScalarBigMapStore,
     makeScalarBigWeakMapStore,
     makeScalarBigSetStore,