add DEBUG

Remote/External.hs

@@ -242,6 +242,7 @@ handleRequest' lck external req mp responsehandler
 		state <- fromMaybe ""
 			<$> getRemoteState (externalUUID external) key
 		send $ VALUE state
+	handleRemoteRequest (DEBUG msg) = liftIO $ debugM "external" msg
 	handleRemoteRequest (VERSION _) =
 		sendMessage lck external $ ERROR "too late to send VERSION"
 

Remote/External/Types.hs

@@ -172,6 +172,7 @@ data RemoteRequest
 	| GETWANTED
 	| SETSTATE Key String
 	| GETSTATE Key
+	| DEBUG String
 	deriving (Show)
 
 instance Receivable RemoteRequest where
@@ -187,6 +188,7 @@ instance Receivable RemoteRequest where
 	parseCommand "GETWANTED" = parse0 GETWANTED
 	parseCommand "SETSTATE" = parse2 SETSTATE
 	parseCommand "GETSTATE" = parse1 GETSTATE
+	parseCommand "DEBUG" = parse1 DEBUG
 	parseCommand _ = parseFail
 
 -- Responses to RemoteRequest.

debian/changelog

@@ -2,7 +2,7 @@ git-annex (5.20140107) unstable; urgency=medium
 
   * mirror: Support --all (and --unused).
   * external special remote protocol: Added GETUUID, GETWANTED, SETWANTED,
-    SETSTATE, GETSTATE.
+    SETSTATE, GETSTATE, DEBUG.
   * Windows: Fix bug in direct mode merge code that could cause files
     in subdirectories to go missing.
   * Windows: Avoid eating stdin when running ssh to add a authorized key,

doc/design/external_special_remote_protocol.mdwn

@@ -233,6 +233,8 @@ in control.
 * `GETSTATE Key`  
   Gets any state that has been stored for the key.  
   (git-annex replies with VALUE followed by the state.)
+* `DEBUG message`
+  Tells git-annex to display the message if --debug is enabled.
 
 ## general messages