GSM: split OnlyBootstrap into PreSyncing and Syncing #975
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ouroboros-consensus-diffusion/src/ouroboros-consensus-diffusion/Ouroboros/Consensus/Node/GSM.hs
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| @@ -78,11 +81,23 @@ data CandidateVersusSelection = | |||
| -- ^ Whether the candidate is better than the selection | |||
| deriving (Eq, Show) | |||
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| data GsmState = | |||
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Is it worth clarifying what GSM is in the comments?
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Added a comment expanding the acronym (it is also in the module header, but that is a bit distanced)
| -> QSM.Commands Command Response | ||
| -> QC.Property | ||
| prop_sequential1 j0 cmds = runSimQC $ do | ||
| prop_sequential1 ctx cmds = runSimQC $ do | ||
| let s0 = case j0 of |
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Maybe s0 and j0 could have more descriptive names.
We still use `LedgerStateJudgement` for initialization, with TooOld corresponding to PreSyncing and YoungEnough corresponding to CaughtUp.
Compared to the previous static predicate, this has the following advantages: - Confirms necessity of `avoidTransientState` (or a similar mechanism) in the ModelPreSyncing logic - Makes necessity of using `isHaaSatisfied` check in `initModel` explicit. - The tests with less than 3 peers perform many more useful state transitions.
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This PR splits the previous OnlyBootstrap state of the GSM into separate PreSyncing and Syncing states, making it ready to be used for Genesis, while allowing to still use the GSM in conjunction with bootstrap peers.
Compared to the Bootstrap Peers IER, there is one more state and two more transition rules, both based on the Honest Availability Assumption (HHA), which the Network layer will try to establish and inform us about, likely by ensuring a minimum amount of (big) ledger peers, see
isHaaSatisfiedinGsmView.The new state transition diagram looks like this:
graph PreSyncing[PreSyncing] Syncing[Syncing] CaughtUp[CaughtUp] PreSyncing -- "Honest Availability Assumption\nis satisfied" --> Syncing Syncing -- "Honest Availability Assumption\nis no longer satisfied" --> PreSyncing Syncing -- "no peers claim to have\nsubsequent headers,\nand its selection is ≥\nthe best header" --> CaughtUp CaughtUp -- "vol tip became older than X" --> PreSyncing StartUp[[Node start-up]] StartUp -- "node was most recently in CaughtUp\nand vol tip is younger than X" --> CaughtUp StartUp -- "otherwise" --> PreSyncing