use P2P protocol for drop

Not yet used for everything else, but this is enough to
verify that it works, and do some benchmarking.

Some bugfixes included, which got it working. Also fallback to old
actions has been verified to work correctly.

Benchmarked dropping one thousand files from a ssh remote on localhost.
Using the old git-annex	40.867 seconds.
With the P2P protocol	9.905 seconds!

This commit was sponsored by Jochen Bartl on Patreon.

5 files changed, 39 insertions, 30 deletions

diff --git a/Command/P2PStdIO.hs b/Command/P2PStdIO.hs
index 73c38b906..cb7e54f28 100644
--- a/Command/P2PStdIO.hs
+++ b/Command/P2PStdIO.hs
@@ -14,25 +14,22 @@ import qualified P2P.Protocol as P2P
 import qualified Annex
 import Annex.UUID
 import qualified CmdLine.GitAnnexShell.Checks as Checks
-import qualified CmdLine.GitAnnexShell.Fields as Fields
 
 cmd :: Command
 cmd = noMessages $ command "p2pstdio" SectionPlumbing
 	"communicate in P2P protocol over stdio"
-	paramNothing (withParams seek)
+	paramUUID (withParams seek)
 
 seek :: CmdParams -> CommandSeek
-seek = withNothing start
+seek [u] = commandAction $ start $ toUUID u
+seek _ = giveup "missing UUID parameter"
 
-start :: CommandStart
-start = do
+start :: UUID -> CommandStart
+start theiruuid = do
 	servermode <- liftIO $ 
 		Checks.checkEnvSet Checks.readOnlyEnv >>= return . \case
 			True -> P2P.ServeReadOnly
 			False -> P2P.ServeReadWrite
-	theiruuid <- Fields.getField Fields.remoteUUID >>= \case
-		Nothing -> giveup "missing remoteuuid field"
-		Just u -> return (toUUID u)
 	myuuid <- getUUID
 	conn <- stdioP2PConnection <$> Annex.gitRepo
 	let server = do
diff --git a/Remote/Git.hs b/Remote/Git.hs
index 328f64217..0edd04117 100644
--- a/Remote/Git.hs
+++ b/Remote/Git.hs
@@ -54,10 +54,11 @@ import Remote.Helper.Export
 import qualified Remote.Helper.Ssh as Ssh
 import qualified Remote.GCrypt
 import qualified Remote.P2P
-import P2P.Address
+import qualified Remote.Helper.P2P as P2PHelper
 import qualified P2P.Protocol as P2P
 import qualified P2P.Annex as P2P
 import qualified P2P.IO as P2P
+import P2P.Address
 import Annex.Path
 import Creds
 import Messages.Progress
@@ -150,11 +151,12 @@ gen r u c gc
 	| otherwise = case repoP2PAddress r of
 		Nothing -> do
 			duc <- mkDeferredUUIDCheck r u gc
-			go duc <$> remoteCost gc defcst
+			connpool <- Ssh.mkP2PSshConnectionPool
+			go duc connpool <$> remoteCost gc defcst
 		Just addr -> Remote.P2P.chainGen addr r u c gc
   where
 	defcst = if repoCheap r then cheapRemoteCost else expensiveRemoteCost
-	go duc cst = Just new
+	go duc connpool cst = Just new
 	  where
 		new = Remote 
 			{ uuid = u
@@ -163,7 +165,7 @@ gen r u c gc
 			, storeKey = copyToRemote new duc
 			, retrieveKeyFile = copyFromRemote new
 			, retrieveKeyFileCheap = copyFromRemoteCheap new
-			, removeKey = dropKey new duc
+			, removeKey = dropKey new duc connpool
 			, lockContent = Just (lockKey new duc)
 			, checkPresent = inAnnex new duc
 			, checkPresentCheap = repoCheap r
@@ -368,8 +370,8 @@ keyUrls r key = map tourl locs'
 	remoteconfig = gitconfig r
 	cfg = remoteGitConfig remoteconfig
 
-dropKey :: Remote -> DeferredUUIDCheck -> Key -> Annex Bool
-dropKey r duc key
+dropKey :: Remote -> DeferredUUIDCheck -> Ssh.P2PSshConnectionPool -> Key -> Annex Bool
+dropKey r duc connpool key
 	| not $ Git.repoIsUrl (repo r) = ifM duc
 		( guardUsable (repo r) (return False) $
 			commitOnCleanup r $ onLocalFast r $ do
@@ -383,7 +385,9 @@ dropKey r duc key
 		, return False
 		)
 	| Git.repoIsHttp (repo r) = giveup "dropping from http remote not supported"
-	| otherwise = commitOnCleanup r $ Ssh.dropKey (repo r) key
+	| otherwise = commitOnCleanup r $ do
+		let fallback = Ssh.dropKey (repo r) key
+		P2PHelper.remove (runProto r connpool fallback) key
 
 lockKey :: Remote -> DeferredUUIDCheck -> Key -> (VerifiedCopy -> Annex r) -> Annex r
 lockKey r duc key callback
@@ -758,12 +762,12 @@ mkDeferredUUIDCheck r u gc
 
 -- Runs a P2P Proto action on a remote when it supports that,
 -- otherwise the fallback action.
-runSsh :: Remote -> Ssh.P2PSshConnectionPool -> Annex a -> P2P.Proto a -> Annex a
-runSsh r connpool fallback proto =
-	Ssh.getP2PSshConnection r connpool >>= maybe fallback go
+runProto :: Remote -> Ssh.P2PSshConnectionPool -> Annex a -> P2P.Proto a -> Annex (Maybe a)
+runProto r connpool fallback proto = Just <$>
+	(Ssh.getP2PSshConnection r connpool >>= maybe fallback go)
   where
 	go c = do
-		(c', v) <- runSsh' proto c
+		(c', v) <- runProtoConn proto c
 		case v of
 			Just res -> do
 				liftIO $ Ssh.storeP2PSshConnection connpool c'
@@ -773,9 +777,9 @@ runSsh r connpool fallback proto =
 			-- connection, and run the fallback.
 			Nothing -> fallback
 
-runSsh' :: P2P.Proto a -> Ssh.P2PSshConnection -> Annex (Ssh.P2PSshConnection, Maybe a)
-runSsh' _ P2P.ClosedConnection = return (P2P.ClosedConnection, Nothing)
-runSsh' a conn@(P2P.OpenConnection (c, _pid)) =
+runProtoConn :: P2P.Proto a -> Ssh.P2PSshConnection -> Annex (Ssh.P2PSshConnection, Maybe a)
+runProtoConn _ P2P.ClosedConnection = return (P2P.ClosedConnection, Nothing)
+runProtoConn a conn@(P2P.OpenConnection (c, _pid)) =
 	P2P.runFullProto P2P.Client c a >>= \case
 		Right r -> return (conn, Just r)
 		-- When runFullProto fails, the connection is no longer
diff --git a/Remote/Helper/Ssh.hs b/Remote/Helper/Ssh.hs
index 96c419dd4..84a1ee8cc 100644
--- a/Remote/Helper/Ssh.hs
+++ b/Remote/Helper/Ssh.hs
@@ -26,7 +26,6 @@ import Config
 import qualified P2P.Protocol as P2P
 import qualified P2P.IO as P2P
 
-import Control.Concurrent.Async
 import Control.Concurrent.STM
 
 toRepo :: ConsumeStdin -> Git.Repo -> RemoteGitConfig -> SshCommand -> Annex (FilePath, [CommandParam])
@@ -192,7 +191,7 @@ closeP2PSshConnection :: P2PSshConnection -> IO P2PSshConnection
 closeP2PSshConnection P2P.ClosedConnection = return P2P.ClosedConnection
 closeP2PSshConnection (P2P.OpenConnection (conn, pid)) = do
 	P2P.closeConnection conn
-	void $ async $ waitForProcess pid
+	void $ waitForProcess pid
 	return P2P.ClosedConnection
 
 -- Pool of connections over ssh to git-annex-shell p2pstdio.
@@ -235,8 +234,10 @@ storeP2PSshConnection connpool conn = atomically $ modifyTVar' connpool $ \case
 -- If the remote does not support the P2P protocol, that's remembered in 
 -- the connection pool.
 openP2PSshConnection :: Remote -> P2PSshConnectionPool -> Annex (Maybe P2PSshConnection)
-openP2PSshConnection r connpool = 
-	git_annex_shell ConsumeStdin (repo r) "p2pstdio" [] [] >>= \case
+openP2PSshConnection r connpool = do
+	u <- getUUID
+	let ps = [Param (fromUUID u)]
+	git_annex_shell ConsumeStdin (repo r) "p2pstdio" ps [] >>= \case
 		Nothing -> do
 			liftIO $ rememberunsupported
 			return Nothing
@@ -254,11 +255,11 @@ openP2PSshConnection r connpool =
 		let conn = P2P.P2PConnection
 			{ P2P.connRepo = repo r
 			, P2P.connCheckAuth = const False
-			, P2P.connIhdl = from
-			, P2P.connOhdl = to
+			, P2P.connIhdl = to
+			, P2P.connOhdl = from
 			}
 		let c = P2P.OpenConnection (conn, pid)
-		-- When the connection is successful, the peer
+		-- When the connection is successful, the remote
 		-- will send an AUTH_SUCCESS with its uuid.
 		tryNonAsync (P2P.runNetProto conn $ P2P.postAuth) >>= \case
 			Right (Right (Just theiruuid)) | theiruuid == uuid r ->
diff --git a/doc/git-annex-shell.mdwn b/doc/git-annex-shell.mdwn
index cf72e091b..fc536e44b 100644
--- a/doc/git-annex-shell.mdwn
+++ b/doc/git-annex-shell.mdwn
@@ -90,12 +90,15 @@ first "/~/" or "/~user/" is expanded to the specified home directory.
 
   Sets up a repository as a gcrypt repository.
 
-* p2pstdio directory
+* p2pstdio directory uuid
 
   This causes git-annex-shell to communicate using the git-annex p2p
   protocol over stdio. When supported by git-annex-shell, this allows
   multiple actions to be run over a single connection, improving speed.
 
+  The uuid is the one belonging to the repository that will be
+  communicating with git-annex-shell.
+
 # OPTIONS
 
 Most options are the same as in git-annex. The ones specific
diff --git a/doc/todo/accellerate_ssh_remotes_with_git-annex-shell_mass_protocol.mdwn b/doc/todo/accellerate_ssh_remotes_with_git-annex-shell_mass_protocol.mdwn
index ff4b8c59d..a592e17a9 100644
--- a/doc/todo/accellerate_ssh_remotes_with_git-annex-shell_mass_protocol.mdwn
+++ b/doc/todo/accellerate_ssh_remotes_with_git-annex-shell_mass_protocol.mdwn
@@ -40,3 +40,7 @@ Implementation todos:
   git-annex-shell recvkey has a speed optimisation, when it's told the file
   being sent is locked, it can avoid an expensive verification.
 * Maybe similar for transfers in the other direction?
+* What happens when the assistant is running and some connections are open
+  and it moves between networks?
+* If it's unable to ssh to a host to run p2pstdio, it will fall back to the
+  old method. What if the host is down, does this double the timeout?