Network.Riak.Value.Resolvable

This module allows storage and retrieval of data encoded using the IsContent typeclass. This provides access to more of Riak's storage features than JSON, e.g. links.

Functions automatically resolve conflicts using Resolvable instances. For instance, if a get returns three siblings, a winner will be chosen using resolve. If a put results in a conflict, a winner will be chosen using resolve, and the winner will be put; this will be repeated until either no conflict occurs or the process has been repeated too many times.

Documentation

class IsContent c where

Methods

parseContent :: RpbContent -> Parser c

toContent :: c -> RpbContent

Instances

IsContent ()

Defined in Network.Riak.Value

Methods

parseContent :: RpbContent -> Parser ()

toContent :: () -> RpbContent

IsContent Value

Defined in Network.Riak.Value

Methods

parseContent :: RpbContent -> Parser Value

toContent :: Value -> RpbContent

IsContent RpbContent

Defined in Network.Riak.Value

Methods

parseContent :: RpbContent -> Parser RpbContent

toContent :: RpbContent -> RpbContent

IsContent a => IsContent (ResolvableMonoid a)

Defined in Network.Riak.Value

Methods

parseContent :: RpbContent -> Parser (ResolvableMonoid a)

toContent :: ResolvableMonoid a -> RpbContent

(FromJSON a, ToJSON a) => IsContent (JSON a)

Defined in Network.Riak.JSON

Methods

parseContent :: RpbContent -> Parser (JSON a)

toContent :: JSON a -> RpbContent

class Show a => Resolvable a where

A type that can automatically resolve a vector clock conflict between two or more versions of a value.

Instances must be symmetric in their behaviour, such that the following law is obeyed:

resolve a b == resolve b a

Otherwise, there are no restrictions on the behaviour of resolve. The result may be a, b, a value derived from a and b, or something else.

If several conflicting siblings are found, resolve will be applied over all of them using a fold, to yield a single "winner".

Methods

resolve :: a -> a -> a

Resolve a conflict between two values.

Instances

Resolvable a => Resolvable (Maybe a)

Defined in Network.Riak.Resolvable.Internal

Methods

resolve :: Maybe a -> Maybe a -> Maybe a

(Show a, Monoid a) => Resolvable (ResolvableMonoid a)

Defined in Network.Riak.Resolvable.Internal

Methods

resolve :: ResolvableMonoid a -> ResolvableMonoid a -> ResolvableMonoid a

data ResolutionFailure

Automated conflict resolution failed.

Constructors

RetriesExceeded

Too many attempts were made to resolve a conflict, with each attempt resulting in another conflict.

The number of retries that the library will attempt is high (64). This makes it extremely unlikely that this exception will be thrown during normal application operation. Instead, this exception is most likely to be thrown as a result of a bug in your application code, for example if your resolve function is misbehaving.

Instances

Eq ResolutionFailure

Defined in Network.Riak.Resolvable.Internal

Methods

(==) :: ResolutionFailure -> ResolutionFailure -> Bool

(/=) :: ResolutionFailure -> ResolutionFailure -> Bool

Show ResolutionFailure

Defined in Network.Riak.Resolvable.Internal

Methods

showsPrec :: Int -> ResolutionFailure -> ShowS

show :: ResolutionFailure -> String

showList :: [ResolutionFailure] -> ShowS

Exception ResolutionFailure

Defined in Network.Riak.Resolvable.Internal

Methods

toException :: ResolutionFailure -> SomeException

fromException :: SomeException -> Maybe ResolutionFailure

displayException :: ResolutionFailure -> String

get :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> Key -> R -> IO (Maybe (a, VClock))

Retrieve a single value. If conflicting values are returned, the Resolvable is used to choose a winner.

getMany :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> [Key] -> R -> IO [Maybe (a, VClock)]

Retrieve multiple values. If conflicting values are returned for a key, the Resolvable is used to choose a winner.

modify

Arguments

:: (Resolvable a, IsContent a)

=> Connection

-> Maybe BucketType

-> Bucket

-> Key

-> R

-> W

-> DW

-> (Maybe a -> IO (a, b))

Modification function. Called with Just the value if the key is present, Nothing otherwise.

-> IO (a, b)

Modify a single value. The value, if any, is retrieved using get; conflict resolution is performed if necessary. The modification function is called on the resulting value, and its result is stored using put, which may again perform conflict resolution.

The result of this function is whatever was returned by put, along with the auxiliary value returned by the modification function.

If the put phase of this function gives up due to apparently being stuck in a conflict resolution loop, it will throw a ResolutionFailure exception.

modify_ :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> Key -> R -> W -> DW -> (Maybe a -> IO a) -> IO a

Modify a single value. The value, if any, is retrieved using get; conflict resolution is performed if necessary. The modification function is called on the resulting value, and its result is stored using put, which may again perform conflict resolution.

The result of this function is whatever was returned by put.

If the put phase of this function gives up due to apparently being stuck in a conflict resolution loop, it will throw a ResolutionFailure exception.

Low-level modification functions

put :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> Key -> Maybe VClock -> a -> W -> DW -> IO (a, VClock)

Store a single value, automatically resolving any vector clock conflicts that arise. A single invocation of this function may involve several roundtrips to the server to resolve conflicts.

If a conflict arises, a winner will be chosen using resolve, and the winner will be stored; this will be repeated until no conflict occurs or a (fairly large) number of retries has been attempted without success.

If this function gives up due to apparently being stuck in a conflict resolution loop, it will throw a ResolutionFailure exception.

put_ :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> Key -> Maybe VClock -> a -> W -> DW -> IO ()

Store a single value, automatically resolving any vector clock conflicts that arise. A single invocation of this function may involve several roundtrips to the server to resolve conflicts.

If a conflict arises, a winner will be chosen using resolve, and the winner will be stored; this will be repeated until no conflict occurs or a (fairly large) number of retries has been attempted without success.

If this function gives up due to apparently being stuck in a conflict resolution loop, it will throw a ResolutionFailure exception.

putMany :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> [(Key, Maybe VClock, a)] -> W -> DW -> IO [(a, VClock)]

Store multiple values, resolving any vector clock conflicts that arise. A single invocation of this function may involve several roundtrips to the server to resolve conflicts.

If any conflicts arise, a winner will be chosen in each case using resolve, and the winners will be stored; this will be repeated until either no conflicts occur or a (fairly large) number of retries has been attempted without success.

For each original value to be stored, the final value that was stored at the end of any conflict resolution is returned.

If this function gives up due to apparently being stuck in a loop, it will throw a ResolutionFailure exception.

putMany_ :: (Resolvable a, IsContent a) => Connection -> Maybe BucketType -> Bucket -> [(Key, Maybe VClock, a)] -> W -> DW -> IO ()

Store multiple values, resolving any vector clock conflicts that arise. A single invocation of this function may involve several roundtrips to the server to resolve conflicts.

If any conflicts arise, a winner will be chosen in each case using resolve, and the winners will be stored; this will be repeated until either no conflicts occur or a (fairly large) number of retries has been attempted without success.

If this function gives up due to apparently being stuck in a loop, it will throw a ResolutionFailure exception.