Splitstore: add support for protecting out of chain references in the blockstore #6777
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Following sync discussion with @Stebalien , we decided that we shouldn't indirect through the chainstore and instead hook the gc hooks directly through DI. |
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| @@ -58,7 +58,7 @@ func ChainBlockService(bs dtypes.ExposedBlockstore, rem dtypes.ChainBitswap) dty | |||
| return blockservice.New(bs, rem) | |||
| } | |||
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| func MessagePool(lc fx.Lifecycle, mpp messagepool.Provider, ds dtypes.MetadataDS, nn dtypes.NetworkName, j journal.Journal) (*messagepool.MessagePool, error) { | |||
| func MessagePool(lc fx.Lifecycle, mpp messagepool.Provider, ds dtypes.MetadataDS, nn dtypes.NetworkName, j journal.Journal, protector dtypes.GCReferenceProtector) (*messagepool.MessagePool, error) { | |||
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This isn't really a dependency, so I assume this would be a separate "invoke" step (next to the splitstore step). But I don't have strong opinions.
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Well, I have strong opinions. Just not about this.
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We could do it with an invoke step, but doing it here avoids all possible races I think.
No strong opinions on this either.
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basically I want to make sure that AddProtector invocations all happen before Start in the splitstore.
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I assume that Start gets called from a hook, which runs after all invokes (IIRC).
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flaky test failure in https://app.circleci.com/pipelines/github/filecoin-project/lotus/15905/workflows/5d4be844-ce96-4922-ac4c-09503c0d3b3e/jobs/205203 Opened issue #6799 I am going to disable the test as it gets on everyone's nerves. |
This adds a mechanism for protecting out-of-chain references during compaction (and in the future gc).
The problem is that we actually have live references in the blockstore, that are not (yet) reachable from the chain. This arises from pending messages in the mpool, and can result in archiving/discarding such messages during compaction even though they are live.
The solution is to do what garbage collecting programming languages do since the beginning of time: add a hook to protect external references.
The hook is hooked[sic] to the mpool through DI.
Open question: are there other such references that need to be protected?