Safe Haskell	None
Language	Haskell2010

Ouroboros.Consensus.Fragment.InFuture

Contents

Clock skew
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 blk])
}
data InFuture blk = InFuture {
- inFutureHeader :: Header blk
- inFutureExceedsClockSkew :: Bool
}
reference :: forall m blk. (Monad m, UpdateLedger blk, HasHardForkHistory blk) => LedgerConfig blk -> ClockSkew -> SystemTime m -> CheckInFuture m blk
data ClockSkew
clockSkewInSeconds :: Double -> ClockSkew
defaultClockSkew :: ClockSkew
dontCheck :: Monad m => CheckInFuture m blk
miracle :: forall 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 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 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.

reference :: forall m blk. (Monad m, UpdateLedger blk, HasHardForkHistory blk) => LedgerConfig blk -> ClockSkew -> SystemTime m -> CheckInFuture m blk Source #

Clock skew

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

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 #
Show ClockSkew Source #
Instance details Defined in Ouroboros.Consensus.Fragment.InFuture Methods showsPrec :: Int -> ClockSkew -> ShowS # show :: ClockSkew -> String # showList :: [ClockSkew] -> ShowS #

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.

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

:: forall 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.