Fix no-op pre prepare #1085
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Fix no-op pre prepare #1085
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fix_noop_pre_prepare@7482 aka 20200421.5 vs master ewma over 50 builds from 7108 to 7476 |
ashamis
reviewed
Apr 20, 2020
ashamis
approved these changes
Apr 20, 2020
achamayou
approved these changes
Apr 21, 2020
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@achamayou that is not a bad idea, I'll see how easy/hard it is to add that. In any case when the view change test is enabled this code path should be crossed in every view change. |
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Adding unit test in separate PR |
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Resolves problem described in #839
The problem here is that the no-op pre-prepare digests were not being calculated consistently during view changes (no-op pre-prepares are created per-replica vs created by one replica and broadcasted to other replicas as is done in normal execution) and so the no-op pre-prepares would never complete.
This fixes that and also puts the no-op pre-prepares into the ledger during view changes. In order for the no-op pp's to go into the ledger, we need them to not be signed, as each no-op pre-prepare will be signed by the replica that created it, leading eventually to an inconsistent merkle tree.
These pre-prepares will be signed eventually as part of the next pre-prepare.