Hasql.Pool

Pool

data Pool

A pool of connections to DB.

acquire :: Int -> Settings -> IO Pool

Given the pool-size and connection settings create a connection-pool.

No connections actually get established by this function. It is delegated to use.

release :: Pool -> IO ()

Release all the connections in the pool.

use :: Pool -> Session a -> IO (Either UsageError a)

Use a connection from the pool to run a session and return the connection to the pool, when finished.

Session failing with a ClientError get interpreted as a loss of connection. In such case the connection does not get returned to the pool and a slot gets freed up for a new connection to be established the next time one is needed. The error still gets returned from this function.

Errors

data UsageError

A union over the connection establishment error and the session error.

Constructors

ConnectionUsageError ConnectionError

SessionUsageError QueryError

PoolIsReleasedUsageError

Instances

Eq UsageError

Defined in Hasql.Pool

Methods

(==) :: UsageError -> UsageError -> Bool

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

Show UsageError

Defined in Hasql.Pool

Methods

showsPrec :: Int -> UsageError -> ShowS

show :: UsageError -> String

showList :: [UsageError] -> ShowS

Exception UsageError

Defined in Hasql.Pool

Methods

toException :: UsageError -> SomeException

fromException :: SomeException -> Maybe UsageError

displayException :: UsageError -> String