Pawan Dhananjay 00cdc4bb35 Update state before producing attestation (#1596) ... ## Issue Addressed Partly addresses #1547 ## Proposed Changes This fix addresses the missing attestations at slot 0 of an epoch (also sometimes slot 1 when slot 0 was skipped). There are 2 cases: 1. BN receives the block for the attestation slot after 4 seconds (1/3rd of the slot). 2. No block is proposed for this slot. In both cases, when we produce the attestation, we pass the head state to the `produce_unaggregated_attestation_for_block` function here 9833eca024/beacon_node/beacon_chain/src/beacon_chain.rs (L845-L850) Since we don't advance the state in this function, we set `attestation.data.source = state.current_justified_checkpoint` which is atleast 2 epochs lower than current_epoch(wall clock epoch). This attestation is invalid and cannot be included in a block because of this assert from the spec: ```python if data.target.epoch == get_current_epoch(state): assert data.source == state.current_justified_checkpoint state.current_epoch_attestations.append(pending_attestation) ``` https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/beacon-chain.md#attestations This PR changes the `produce_unaggregated_attestation_for_block` function to ensure that it advances the state before producing the attestation at the new epoch. Running this on my node, have missed 0 attestations across all 8 of my validators in a 100 epoch period 🎉 To compare, I was missing ~14 attestations across all 8 validators in the same 100 epoch period before the fix. Will report missed attestations if any after running for another 100 epochs tomorrow.		2020-09-08 11:25:43 +00:00
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src	Update state before producing attestation (#1596)	2020-09-08 11:25:43 +00:00
tests	Alternative (to BeaconChainHarness) BeaconChain testing API (#1380)	2020-08-26 09:24:55 +00:00
Cargo.toml	Avoid Printing Binary String to Logs (#1576)	2020-09-05 05:46:25 +00:00