graphql-engine/server/src-lib/Hasura/Incremental.hs
David Overton cbddcce26b Data connector cache invalidations
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5820
GitOrigin-RevId: ded80e378901cc0c0ca12eb67d9264756a8d6ff4
2022-09-14 13:00:47 +00:00

53 lines
1.6 KiB
Haskell

-- | A simple implementation of /incremental build rules/, which can be used to avoid unnecessary
-- recomputation on incrementally-changing input. See 'Rule' for more details.
module Hasura.Incremental
( -- * The @Rule@ datatype
Rule,
Result,
build,
rebuild,
rebuildRule,
result,
-- * Abstract interface
ArrowDistribute (..),
ArrowCache (..),
MonadDepend (..),
DependT,
-- * Fine-grained dependencies
Dependency,
Select (Selector),
selectD,
selectKeyD,
selectMaybeD,
Cacheable (..),
Accesses,
-- * Cache invalidation
InvalidationKey,
initialInvalidationKey,
invalidate,
)
where
import Hasura.Incremental.Internal.Cache
import Hasura.Incremental.Internal.Dependency
import Hasura.Incremental.Internal.Rule
import Hasura.Incremental.Select
import Hasura.Prelude
-- | A simple helper type that can be used to implement explicit cache invalidation. Internally,
-- each 'InvalidationKey' is a counter; 'initialInvalidationKey' starts the counter at 0 and
-- 'invalidate' increments it by 1. Two 'InvalidationKey's are equal iff they have the same internal
-- count, so depending on an 'InvalidationKey' provides a mechanism to force portions of the build
-- process to be reexecuted by calling 'invalidate' before running the build.
newtype InvalidationKey = InvalidationKey Int
deriving (Show, Eq, Ord, Cacheable)
initialInvalidationKey :: InvalidationKey
initialInvalidationKey = InvalidationKey 0
invalidate :: InvalidationKey -> InvalidationKey
invalidate (InvalidationKey n) = InvalidationKey (n + 1)