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{-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies #-}
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{-| Implementation of the RPC client.
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-}
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{-
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Copyright (C) 2012 Google Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA.
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-}
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module Ganeti.Rpc
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( RpcCall
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, RpcResult
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, Rpc
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, RpcError(..)
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, rpcCallName
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, rpcCallTimeout
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, rpcCallData
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, rpcCallAcceptOffline
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, rpcResultFill
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) where
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import qualified Text.JSON as J
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import Ganeti.Objects
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-- | Data type for RPC error reporting.
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data RpcError
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= CurlDisabledError
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| CurlLayerError Node String
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| JsonDecodeError String
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| OfflineNodeError Node
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deriving Eq
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instance Show RpcError where
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show CurlDisabledError =
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"RPC/curl backend disabled at compile time"
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show (CurlLayerError node code) =
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"Curl error for " ++ nodeName node ++ ", error " ++ code
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show (JsonDecodeError msg) =
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"Error while decoding JSON from HTTP response " ++ msg
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show (OfflineNodeError node) =
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"Node " ++ nodeName node ++ " is marked as offline"
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rpcErrorJsonReport :: (Monad m) => J.Result a -> m (Either RpcError a)
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rpcErrorJsonReport (J.Error x) = return $ Left $ JsonDecodeError x
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rpcErrorJsonReport (J.Ok x) = return $ Right x
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-- | A generic class for RPC calls.
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class (J.JSON a) => RpcCall a where
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-- | Give the (Python) name of the procedure.
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rpcCallName :: a -> String
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-- | Calculate the timeout value for the call execution.
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rpcCallTimeout :: a -> Int
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-- | Prepare arguments of the call to be send as POST.
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rpcCallData :: Node -> a -> String
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-- | Whether we accept offline nodes when making a call.
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rpcCallAcceptOffline :: a -> Bool
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rpcCallData _ = J.encode
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-- | A generic class for RPC results with default implementation.
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class (J.JSON a) => RpcResult a where
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-- | Create a result based on the received HTTP response.
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rpcResultFill :: (Monad m) => String -> m (Either RpcError a)
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rpcResultFill res = rpcErrorJsonReport $ J.decode res
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-- | Generic class that ensures matching RPC call with its respective
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-- result.
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class (RpcCall a, RpcResult b) => Rpc a b | a -> b
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