CRDT.LWW

Documentation

data LWW a

Last write wins. Assuming timestamp is unique. This type is both CmRDT and CvRDT.

Timestamps are assumed unique, totally ordered, and consistent with causal order; i.e., if assignment 1 happened-before assignment 2, the former’s timestamp is less than the latter’s.

Constructors

LWW

Fields

• value :: !a
• time :: !LamportTime

Instances

Eq a => Eq (LWW a)

Methods

(==) :: LWW a -> LWW a -> Bool

(/=) :: LWW a -> LWW a -> Bool

Show a => Show (LWW a)

Methods

showsPrec :: Int -> LWW a -> ShowS

show :: LWW a -> String

showList :: [LWW a] -> ShowS

Eq a => Semigroup (LWW a)

Merge by choosing more recent timestamp.

Methods

(<>) :: LWW a -> LWW a -> LWW a

sconcat :: NonEmpty (LWW a) -> LWW a

stimes :: Integral b => b -> LWW a -> LWW a

Eq a => Semilattice (LWW a)

See CvRDT

Eq a => CmRDT (LWW a)

Associated Types

type Intent (LWW a) :: *

type Payload (LWW a) :: *

Methods

initial :: Payload (LWW a)

makeOp :: Clock m => Intent (LWW a) -> Payload (LWW a) -> Maybe (m (LWW a))

apply :: LWW a -> Payload (LWW a) -> Payload (LWW a)

CausalOrd (LWW a)

Methods

precedes :: LWW a -> LWW a -> Bool

type Intent (LWW a)

type Intent (LWW a) = a

type Payload (LWW a)

type Payload (LWW a) = Maybe (LWW a)

CvRDT

initialize :: Clock m => a -> m (LWW a)

Initialize state

assign :: Clock m => a -> LWW a -> m (LWW a)

Change state as CvRDT operation. Current value is ignored, because new timestamp is always greater.

query :: LWW a -> a

Query state

Implementation detail

advanceFromLWW :: Clock m => LWW a -> m ()