Safe Haskell	Safe-Inferred
Language	Haskell2010

Ouroboros.Consensus.Fragment.InFuture

Contents

Clock skew
- not exporting the constructor
Testing

Description

Intended for qualified import

import Ouroboros.Consensus.Fragment.InFuture (CheckInFuture(..), ClockSkew(..))
import qualified Ouroboros.Consensus.Fragment.InFuture as InFuture

Synopsis

data CheckInFuture m blk = CheckInFuture {
- checkInFuture ∷ ValidatedFragment (Header blk) (LedgerState blk) → m (AnchoredFragment (Header blk), [InFuture m blk])
}
data InFuture m blk = InFuture {
- inFutureHeader ∷ Header blk
- inFutureExceedsClockSkew ∷ Bool
- inFuturePunish ∷ InvalidBlockPunishment m
}
reference ∷ ∀ m blk. (Monad m, UpdateLedger blk, HasHardForkHistory blk) ⇒ LedgerConfig blk → ClockSkew → SystemTime m → CheckInFuture m blk
clockSkewInSeconds ∷ Double → ClockSkew
defaultClockSkew ∷ ClockSkew
data ClockSkew
unClockSkew ∷ ClockSkew → NominalDiffTime
dontCheck ∷ Monad m ⇒ CheckInFuture m blk
miracle ∷ ∀ m blk. (MonadSTM m, HasHeader (Header blk)) ⇒ STM m SlotNo → Word64 → CheckInFuture m blk

Documentation

data CheckInFuture m blk Source #

Constructors

CheckInFuture
Fields checkInFuture ∷ ValidatedFragment (Header blk) (LedgerState blk) → m (AnchoredFragment (Header blk), [InFuture m blk]) POSTCONDITION: checkInFuture vf >>= \(af, fut) -> validatedFragment vf == af <=> null fut

Instances

Instances details

NoThunks (CheckInFuture m blk) Source #
Instance details Defined in Ouroboros.Consensus.Fragment.InFuture Methods noThunks ∷ Context → CheckInFuture m blk → IO (Maybe ThunkInfo) Source # wNoThunks ∷ Context → CheckInFuture m blk → IO (Maybe ThunkInfo) Source # showTypeOf ∷ Proxy (CheckInFuture m blk) → String Source #

data InFuture m blk Source #

Header of block that we found to be in the future

Constructors

InFuture
Fields inFutureHeader ∷ Header blk The header itself inFutureExceedsClockSkew ∷ Bool Whether or not this header exceeded the allowed clock skew Headers that do exceed the clock skew should be considered invalid. inFuturePunish ∷ InvalidBlockPunishment m `blockPunish`

reference ∷ ∀ m blk. (Monad m, UpdateLedger blk, HasHardForkHistory blk) ⇒ LedgerConfig blk → ClockSkew → SystemTime m → CheckInFuture m blk Source #

Clock skew

clockSkewInSeconds ∷ Double → ClockSkew Source #

Specify maximum clock skew in seconds

defaultClockSkew ∷ ClockSkew Source #

Default maximum permissible clock skew

See ClockSkew for details. We allow for 5 seconds skew by default.

not exporting the constructor

data ClockSkew Source #

Maximum permissible clock skew

When running NTP, systems clocks will never be perfectly synchronized. The maximum clock skew records how much of a difference we consider acceptable.

For example. Suppose

Two nodes A and B
A's clock is 0.5 ahead of B's
A produces a block and sends it to B
When B translates the SlotNo of that block to a time, it may find that it is 0.5 seconds ahead of its current clock (worst case).

The maximum permissible clock skew decides if B will consider this block to be valid (even if it will not yet consider it for chain seleciton) or as invalid (and disconnect from A, since A is sending it invalid blocks).

Use defaultClockSkew when unsure.

Instances

Instances details

Show ClockSkew Source #
Instance details Defined in Ouroboros.Consensus.Fragment.InFuture Methods showsPrec ∷ Int → ClockSkew → ShowS # show ∷ ClockSkew → String # showList ∷ [ClockSkew] → ShowS #
Eq ClockSkew Source #
Instance details Defined in Ouroboros.Consensus.Fragment.InFuture Methods (==) ∷ ClockSkew → ClockSkew → Bool # (/=) ∷ ClockSkew → ClockSkew → Bool #
Ord ClockSkew Source #
Instance details Defined in Ouroboros.Consensus.Fragment.InFuture Methods compare ∷ ClockSkew → ClockSkew → Ordering # (<) ∷ ClockSkew → ClockSkew → Bool # (<=) ∷ ClockSkew → ClockSkew → Bool # (>) ∷ ClockSkew → ClockSkew → Bool # (>=) ∷ ClockSkew → ClockSkew → Bool # max ∷ ClockSkew → ClockSkew → ClockSkew # min ∷ ClockSkew → ClockSkew → ClockSkew #

unClockSkew ∷ ClockSkew → NominalDiffTime Source #

Testing

dontCheck ∷ Monad m ⇒ CheckInFuture m blk Source #

Trivial InFuture check that doesn't do any check at all

This is useful for testing and tools such as the DB converter.

miracle Source #

Arguments

∷ ∀ m blk. (MonadSTM m, HasHeader (Header blk))
⇒ STM m SlotNo	Get current slot
→ Word64	Maximum clock skew (in terms of slots)
→ CheckInFuture m blk

If by some miracle we have a function that can always tell us what the correct slot is, implementing CheckInFuture is easy

NOTE: Use of miracle in tests means that none of the hard fork infrastructure for converting slots to time is tested.