Next slot state caching #8357
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Next slot state caching #8357
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Codecov Report
@@ Coverage Diff @@
## develop #8357 +/- ##
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- Coverage 57.89% 57.87% -0.03%
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Files 457 458 +1
Lines 32076 32113 +37
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+ Hits 18570 18584 +14
- Misses 10674 10696 +22
- Partials 2832 2833 +1 |
rauljordan
reviewed
Jan 29, 2021
| // Updating next slot state cache can happen in the background. It shouldn't block rest of the process. | ||
| go func() { | ||
| if err := state.UpdateNextSlotCache(ctx, blockRoot[:], postState); err != nil { | ||
| log.WithError(err).Warn("could not update next slot state cache") |
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Consider debug here, warn is not actionable to users
| // GetNextSlotState returns the saved state if the input root matches the root in `nextSlotCache`. Returns nil otherwise. | ||
| // This is useful to check before processing slots. With a cache hit, it will return last processed state with slot plus | ||
| // one advancement. | ||
| func GetNextSlotState(ctx context.Context, root []byte) (*state.BeaconState, error) { |
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Do we want the naming convention of Get? I guess yes because that's what we use for caches typically, right
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Good point. Removed
| // This is useful to check before processing slots. With a cache hit, it will return last processed state with slot plus | ||
| // one advancement. | ||
| func GetNextSlotState(ctx context.Context, root []byte) (*state.BeaconState, error) { | ||
| nsc.Lock() |
| nsc.RLock() | ||
| // Returning early if state exists in cache. | ||
| if bytes.Equal(root, nsc.root) { | ||
| defer nsc.RUnlock() |
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Suggested change
| defer nsc.RUnlock() | |
| nsc.RUnlock() |
| // Execute per slots transition. | ||
| state, err = ProcessSlots(ctx, state, signed.Block.Slot) | ||
| // Check whether the parent state has been advanced by 1 slot in next slot cache. | ||
| tsState, err := GetNextSlotState(ctx, signed.Block.ParentRoot) |
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that is ts as a prefix? Perhaps we can use a more informative name
terencechain
commented
Jan 29, 2021
| // This is useful to call after successfully processing a block. | ||
| func UpdateNextSlotCache(ctx context.Context, root []byte, state *state.BeaconState) error { | ||
| // Advancing one slot by using a copied state. | ||
| copied := state.Copy() |
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I dont think we need to copy here, but im still doing it to be safe. Any preference on removing it and adding an explicit comment? @nisdas
I wonder if the performance trade off is worth it
rauljordan
approved these changes
Jan 29, 2021
This was referenced Feb 1, 2021
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What type of PR is this?
What does this PR do? Why is it needed?
Credit to @paulhauner for the idea and the motivation
This PR adds the next slot state cache to enable state slot advancement during trialing slot. This is to optimize process epoch bottlenecks + late block arrivals that we have seen in the wild.
Accompany design doc: https://hackmd.io/BFHjQn4VTjO3JhlSSyDTWw?view
Which issues(s) does this PR fix?
N/A
Other notes for review
statepkg thancachepkg to live next to implementation and avoid import cycle. It callsProcessSlots