Blocks until a a lock on the config is obtained.
Signed-off-by: Niklas Hambuechen <[email protected]>
---
src/Ganeti/WConfd/Client.hs | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/src/Ganeti/WConfd/Client.hs b/src/Ganeti/WConfd/Client.hs
index 105de8e..7ed7424 100644
--- a/src/Ganeti/WConfd/Client.hs
+++ b/src/Ganeti/WConfd/Client.hs
@@ -29,8 +29,13 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
module Ganeti.WConfd.Client where
+import Control.Exception.Lifted (finally)
+
import Ganeti.THH.HsRPC
import Ganeti.Constants
+import Ganeti.JSON (unMaybeForJSON)
+import Ganeti.Locking.Locks (ClientId)
+import Ganeti.Objects (ConfigData)
import Ganeti.UDSServer (ConnectConfig(..), Client, connectClient)
import Ganeti.WConfd.Core (exportedFunctions)
@@ -50,3 +55,26 @@ wconfdConnectConfig = ConnectConfig { recvTmo =
wconfdDefRwto
-- configuration and timeout.
getWConfdClient :: FilePath -> IO Client
getWConfdClient = connectClient wconfdConnectConfig wconfdDefCtmo
+
+-- * Helper functions for getting a remote lock
+
+-- | Calls the `lockConfig` RPC until the (unshared) log is obtained.
+waitLockConfig :: ClientId
+ -> Bool -- ^ whether the lock shall be in shared mode
+ -> RpcClientMonad ConfigData
+waitLockConfig c shared = do
+ mConfigData <- lockConfig c shared
+ case unMaybeForJSON mConfigData of
+ Just configData -> return configData
+ Nothing -> waitLockConfig c shared
+
+-- | Calls the `lockConfig` RPC until the (unshared) log is obtained,
+-- runs a function on the obtained config, and calls `unlockConfig`.
+withLockedConfig :: ClientId
+ -> Bool -- ^ whether the lock shall be in shared mode
+ -> (ConfigData -> RpcClientMonad a) -- ^ action to run
+ -> RpcClientMonad a
+withLockedConfig c shared f
+ = (waitLockConfig c shared >>= f)
+ `finally`
+ unlockConfig c -- Unlock config even if something throws.
--
2.1.0.rc2.206.gedb03e5
