make git-remote-daemon ssh transport robust

* Remote system might be available, and connection get lost. Should
  reconnect, but needs to avoid bad behavior (ie, constant reconnect
  attempts.) Use exponential backoff.

* Detect if old system had a too old git-annex-shell, and show the user
  a nice message in the webapp. Required parsing error messages, so perhaps
  this code shoudl be removed once enough time has passed..

* Switch the protocol to using remote URI's, rather than remote names.
  Names change. Also avoids issues with serialization of names containing
  whitespace.

This is nearly ready for merge into master now. I'd still like to make the ssh
transport smarter about reusing ssh connection caching during git pull.

This commit was sponsored by Jim Paris.

1 files changed, 20 insertions, 8 deletions

diff --git a/RemoteDaemon/Types.hs b/RemoteDaemon/Types.hs
index 025c602df..eef7389cc 100644
--- a/RemoteDaemon/Types.hs
+++ b/RemoteDaemon/Types.hs
@@ -10,15 +10,20 @@
 
 module RemoteDaemon.Types where
 
+import Common
 import qualified Annex
 import qualified Git.Types as Git
 import qualified Utility.SimpleProtocol as Proto
 
+import Network.URI
 import Control.Concurrent
 
+-- The URI of a remote is used to uniquely identify it (names change..)
+newtype RemoteURI = RemoteURI URI
+
 -- A Transport for a particular git remote consumes some messages
 -- from a Chan, and emits others to another Chan.
-type Transport = RemoteRepo -> RemoteName -> TransportHandle -> Chan Consumed -> Chan Emitted -> IO ()
+type Transport = RemoteRepo -> RemoteURI -> TransportHandle -> Chan Consumed -> Chan Emitted -> IO ()
 
 type RemoteRepo = Git.Repo
 type LocalRepo = Git.Repo
@@ -28,10 +33,11 @@ data TransportHandle = TransportHandle LocalRepo (MVar Annex.AnnexState)
 
 -- Messages that the daemon emits.
 data Emitted
-	= CONNECTED RemoteName
-	| DISCONNECTED RemoteName
-	| SYNCING RemoteName
-	| DONESYNCING Bool RemoteName
+	= CONNECTED RemoteURI
+	| DISCONNECTED RemoteURI
+	| SYNCING RemoteURI
+	| DONESYNCING RemoteURI Bool
+	| WARNING RemoteURI String
 
 -- Messages that the deamon consumes.
 data Consumed
@@ -41,7 +47,6 @@ data Consumed
 	| RELOAD
 	| STOP
 
-type RemoteName = String
 type RefList = [Git.Ref]
 
 instance Proto.Sendable Emitted where
@@ -51,8 +56,10 @@ instance Proto.Sendable Emitted where
 		["DISCONNECTED", Proto.serialize remote]
 	formatMessage (SYNCING remote) =
 		["SYNCING", Proto.serialize remote]
-	formatMessage (DONESYNCING status remote) =
-		["DONESYNCING", Proto.serialize status, Proto.serialize remote]
+	formatMessage (DONESYNCING remote status) =
+		["DONESYNCING", Proto.serialize remote, Proto.serialize status]
+	formatMessage (WARNING remote message) =
+		["WARNING", Proto.serialize remote, Proto.serialize message]
 
 instance Proto.Sendable Consumed where
 	formatMessage PAUSE = ["PAUSE"]
@@ -66,6 +73,7 @@ instance Proto.Receivable Emitted where
 	parseCommand "DISCONNECTED" = Proto.parse1 DISCONNECTED
 	parseCommand "SYNCING" = Proto.parse1 SYNCING
 	parseCommand "DONESYNCING" = Proto.parse2 DONESYNCING
+	parseCommand "WARNING" = Proto.parse2 WARNING
 	parseCommand _ = Proto.parseFail
 
 instance Proto.Receivable Consumed where
@@ -76,6 +84,10 @@ instance Proto.Receivable Consumed where
 	parseCommand "STOP" = Proto.parse0 STOP
 	parseCommand _ = Proto.parseFail
 
+instance Proto.Serializable RemoteURI where
+	serialize (RemoteURI u) = show u
+	deserialize = RemoteURI <$$> parseURI
+
 instance Proto.Serializable [Char] where
 	serialize = id
 	deserialize = Just