Copyright	(c) David Terei 2016
License	BSD
Maintainer	code@davidterei.com
Stability	stable
Portability	GHC
Safe Haskell	Safe-Inferred
Language	Haskell2010

Database.Memcache.Cluster

Contents

Cluster
Operations

Description

Handles a group of connections to different Memcached servers.

We use consistent hashing to choose which server to route a request to. On an error, we mark the server as failed and remove it temporarialy from the set of servers available.

Synopsis

data Cluster
data ServerSpec = ServerSpec {
- ssHost :: HostName
- ssPort :: ServiceName
- ssAuth :: Authentication
}
data Options = Options {
- optsServerRetries :: Retries
- optsFailRetryDelay :: Milli
- optsDeadRetryDelay :: Milli
- optsServerTimeout :: Milli
- optsGetServerForKey :: Cluster -> Key -> IO (Maybe Server)
}
newCluster :: [ServerSpec] -> Options -> IO Cluster
type Retries = Int
keyedOp :: Cluster -> Key -> Request -> IO Response
anyOp :: Cluster -> Request -> IO Response
allOp :: Cluster -> Request -> IO [(Server, Response)]
allOp' :: Cluster -> (Server -> IO a) -> IO [(Server, a)]

Cluster

data Cluster Source #

Memcached cluster.

data ServerSpec Source #

ServerSpec specifies a server configuration for connection.

Constructors

ServerSpec
Fields ssHost :: HostName Hostname of server to connect to. ssPort :: ServiceName Port number server is running on. ssAuth :: Authentication Authentication values to use for SASL authentication with this server.

Instances

Instances details

Show ServerSpec Source #
Instance details Defined in Database.Memcache.Cluster Methods showsPrec :: Int -> ServerSpec -> ShowS # show :: ServerSpec -> String # showList :: [ServerSpec] -> ShowS #
Default ServerSpec Source #
Instance details Defined in Database.Memcache.Cluster Methods def :: ServerSpec #
Eq ServerSpec Source #
Instance details Defined in Database.Memcache.Cluster Methods (==) :: ServerSpec -> ServerSpec -> Bool # (/=) :: ServerSpec -> ServerSpec -> Bool #

data Options Source #

Options specifies how a Memcached cluster should be configured.

Constructors

Options

Fields

optsServerRetries :: Retries
Number of times to retry an operation on failure. If consecutive failures exceed this value for a server, we mark it as down and failover to a different server for the next operation.
Default is 2.
optsFailRetryDelay :: Milli
After an operation has failed, how long to wait before retrying it while still within the optsServerRetries count?
Default is 200ms.
optsDeadRetryDelay :: Milli
How long to wait after a server has been marked down, before trying to use it again.
Default is 1500ms.
optsServerTimeout :: Milli
How long to wait for an operation to complete before considering it failed.
Default is 750ms.
optsGetServerForKey :: Cluster -> Key -> IO (Maybe Server)
Figure out which server to talk to for a given key.
Default is getServerForKeyDefault.

Instances

Instances details

Default Options Source #
Instance details Defined in Database.Memcache.Cluster Methods def :: Options #

newCluster :: [ServerSpec] -> Options -> IO Cluster Source #

Establish a new connection to a group of Memcached servers.

Operations

type Retries = Int Source #

Number of times to retry an operation before considering it failed.

keyedOp :: Cluster -> Key -> Request -> IO Response Source #

Run a Memcached operation against a particular server, handling any failures that occur, retrying the specified number of times.

anyOp :: Cluster -> Request -> IO Response Source #

Run a Memcached operation against any single server in the cluster, handling any failures that occur, retrying the specified number of times.

allOp :: Cluster -> Request -> IO [(Server, Response)] Source #

Run a Memcached operation against all servers in the cluster, handling any failures that occur, retrying the specified number of times.

allOp' :: Cluster -> (Server -> IO a) -> IO [(Server, a)] Source #

Run a Memcached operation against all servers in the cluster, handling any failures that occur, retrying the specified number of times. Similar to anyOp but allows more flexible interaction with the Server than a single request and response.