-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | A pool of connections for Hasql
--   
--   A pool of connections for Hasql
@package hasql-pool
@version 0.7.2

module Hasql.Pool

-- | A pool of connections to DB.
data Pool

-- | Given the pool-size and connection settings create a connection-pool.
--   
--   No connections actually get established by this function. It is
--   delegated to <a>use</a>.
acquire :: Int -> Settings -> IO Pool

-- | Given the pool-size and connection settings constructor action create
--   a connection-pool.
--   
--   No connections actually get established by this function. It is
--   delegated to <a>use</a>.
--   
--   In difference to <a>acquire</a> new settings get fetched each time a
--   connection is created. This may be useful for some security models.
acquireDynamically :: Int -> IO Settings -> IO Pool

-- | Release all the connections in the pool.
release :: Pool -> IO ()

-- | Use a connection from the pool to run a session and return the
--   connection to the pool, when finished.
--   
--   Session failing with a <a>ClientError</a> gets 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.
use :: Pool -> Session a -> IO (Either UsageError a)

-- | Union over all errors that <a>use</a> can result in.
data UsageError

-- | Attempt to establish a connection failed.
ConnectionUsageError :: ConnectionError -> UsageError

-- | Session execution failed.
SessionUsageError :: QueryError -> UsageError

-- | Attempt to use a pool, which has already been called <a>release</a>
--   upon.
PoolIsReleasedUsageError :: UsageError
instance GHC.Classes.Eq Hasql.Pool.UsageError
instance GHC.Show.Show Hasql.Pool.UsageError
instance GHC.Exception.Type.Exception Hasql.Pool.UsageError