Haxl.Core.DataCache

A cache mapping data requests to their results. This module is provided for access to Haxl internals only; most users should not need to import it.

Documentation

data DataCache res

The DataCache maps things of type f a to ResultVar a, for any f and a provided f a is an instance of Typeable. In practice f a will be a request type parameterised by its result.

See the definition of ResultVar for more details.

empty :: DataCache res

A new, empty DataCache.

insert

Arguments

:: (Hashable (req a), Typeable (req a), Eq (req a), Show (req a), Show a)

=> req a

Request

-> res a

Result

-> DataCache res

-> DataCache res

Inserts a request-result pair into the DataCache.

insertNotShowable

Arguments

:: (Hashable (req a), Typeable (req a), Eq (req a))

=> req a

Request

-> res a

Result

-> DataCache res

-> DataCache res

Inserts a request-result pair into the DataCache, without requiring Show instances of the request or the result. The cache cannot be subsequently used with showCache.

lookup

Arguments

:: Typeable (req a)

=> req a

Request

-> DataCache res

-> Maybe (res a)

Looks up the cached result of a request.

showCache :: DataCache ResultVar -> IO [(TypeRep, [(String, Either SomeException String)])]

Dumps the contents of the cache, with requests and responses converted to Strings using show. The entries are grouped by TypeRep. Note that this will fail if insertNotShowable has been used to insert any entries.