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feat(SwingSet): add "reachable" flag to clist entries
The kernel-to-vat clist entry for `kref` is stored in the kernelDB under a
key of `${vatID}.c.${kref}` . This changes the value at that key from
`${vref}` to `${flag} ${vref}`, where `flag` is either `R` (for "reachable
and recognizable") or `_` (for "recognizable but not reachable). The "neither
reachable nor recognizable" state simply deletes the clist entry altogether.
This adds vatKeeper methods to set and clear the flag on a given kref. These
will be used by the GC syscall handlers for dropImport and friends.
closes #3108- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,89 @@ | ||
| import { test } from '../tools/prepare-test-env-ava'; | ||
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| // eslint-disable-next-line import/order | ||
| import { initSwingStore } from '@agoric/swing-store-simple'; | ||
| import { makeDummySlogger } from '../src/kernel/slogger'; | ||
| import makeKernelKeeper from '../src/kernel/state/kernelKeeper'; | ||
| import { wrapStorage } from '../src/kernel/state/storageWrapper'; | ||
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| test(`clist reachability`, async t => { | ||
| const slog = makeDummySlogger({}); | ||
| const { enhancedCrankBuffer: s } = wrapStorage(initSwingStore().kvStore); | ||
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| const kk = makeKernelKeeper(s, slog); | ||
| kk.createStartingKernelState('local'); | ||
| const vatID = kk.allocateUnusedVatID(); | ||
| const vk = kk.allocateVatKeeper(vatID); | ||
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||
| t.is(vk.mapKernelSlotToVatSlot('ko1'), 'o-50'); | ||
| t.is(vk.mapKernelSlotToVatSlot('ko2'), 'o-51'); | ||
| t.is(vk.mapKernelSlotToVatSlot('ko1'), 'o-50'); | ||
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| t.is(vk.mapVatSlotToKernelSlot('o+1'), 'ko20'); | ||
| t.is(vk.mapVatSlotToKernelSlot('o+2'), 'ko21'); | ||
| t.is(vk.mapVatSlotToKernelSlot('o+1'), 'ko20'); | ||
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| t.is(s.get(`${vatID}.c.o+1`), `ko20`); | ||
| t.is(s.get(`${vatID}.c.ko20`), 'R o+1'); | ||
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||
| // newly allocated imports are marked as reachable | ||
| t.is(s.get(`${vatID}.c.ko1`), 'R o-50'); | ||
| // now pretend that the vat drops its o-50 import: the syscall.dropImport | ||
| // will cause the kernel to clear the reachability flag | ||
| vk.clearReachableFlag('ko1'); | ||
| t.is(s.get(`${vatID}.c.ko1`), '_ o-50'); | ||
| // while dropped, the vat may not access the import | ||
| t.throws(() => vk.mapVatSlotToKernelSlot('o-50'), { | ||
| message: /vat tried to access unreachable import/, | ||
| }); | ||
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| // now the kernel sends a new message that references ko1, causing a | ||
| // re-import | ||
| vk.setReachableFlag('ko1'); | ||
| t.is(s.get(`${vatID}.c.ko1`), 'R o-50'); | ||
| // re-import without intervening dropImport is idempotent | ||
| vk.setReachableFlag('ko1'); | ||
| t.is(s.get(`${vatID}.c.ko1`), 'R o-50'); | ||
|
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||
| // test the same thing for exports | ||
| t.is(s.get(`${vatID}.c.ko20`), 'R o+1'); | ||
| // kernel tells vat that kernel is dropping the export, clearing the | ||
| // reachability flag | ||
| vk.clearReachableFlag('ko20'); | ||
| t.is(s.get(`${vatID}.c.ko20`), '_ o+1'); | ||
| // while dropped, access by the kernel indicates a bug | ||
| t.throws(() => vk.mapKernelSlotToVatSlot('ko20'), { | ||
| message: /kernel sent unreachable export/, | ||
| }); | ||
|
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||
| // vat re-exports o+1 | ||
| vk.setReachableFlag('ko20'); | ||
| t.is(s.get(`${vatID}.c.ko20`), 'R o+1'); | ||
| // re-export without intervening dropExport is idempotent | ||
| vk.setReachableFlag('ko20'); | ||
| t.is(s.get(`${vatID}.c.ko20`), 'R o+1'); | ||
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| // test setReachable=false, used by handlers for GC operations like | ||
| // syscall.dropImport to talk about an import without claiming it's | ||
| // reachable or causing it to become reachable | ||
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| t.is(vk.mapKernelSlotToVatSlot('ko3'), 'o-52'); | ||
| vk.clearReachableFlag('ko3'); | ||
| t.is(s.get(`${vatID}.c.ko3`), '_ o-52'); | ||
| t.throws(() => vk.mapVatSlotToKernelSlot('o-52'), { | ||
| message: /vat tried to access unreachable import/, | ||
| }); | ||
| t.is(vk.mapVatSlotToKernelSlot('o-52', false), 'ko3'); | ||
| t.is(vk.mapKernelSlotToVatSlot('ko3', false), 'o-52'); | ||
| t.is(s.get(`${vatID}.c.ko3`), '_ o-52'); | ||
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| t.is(vk.mapVatSlotToKernelSlot('o+3'), 'ko22'); | ||
| vk.clearReachableFlag('ko22'); | ||
| t.is(s.get(`${vatID}.c.ko22`), '_ o+3'); | ||
| t.throws(() => vk.mapKernelSlotToVatSlot('ko22'), { | ||
| message: /kernel sent unreachable export/, | ||
| }); | ||
| t.is(vk.mapKernelSlotToVatSlot('ko22', false), 'o+3'); | ||
| t.is(vk.mapVatSlotToKernelSlot('o+3', false), 'ko22'); | ||
| t.is(s.get(`${vatID}.c.ko22`), '_ o+3'); | ||
| }); |