From 14ccfc0abc1aa3130b07e7bd981b266f2eccd751 Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Fri, 22 Nov 2013 23:12:06 -0400
Subject: assistant restart on upgrade

---
 Assistant/Threads/UpgradeWatcher.hs | 64 +++++++++++++++++++++++++++++++------
 1 file changed, 55 insertions(+), 9 deletions(-)

(limited to 'Assistant/Threads/UpgradeWatcher.hs')

diff --git a/Assistant/Threads/UpgradeWatcher.hs b/Assistant/Threads/UpgradeWatcher.hs
index cbfefdbbc..707dc0f1d 100644
--- a/Assistant/Threads/UpgradeWatcher.hs
+++ b/Assistant/Threads/UpgradeWatcher.hs
@@ -5,6 +5,8 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE CPP #-}
+
 module Assistant.Threads.UpgradeWatcher (
 	upgradWatcherThread
 ) where
@@ -13,19 +15,29 @@ import Assistant.Common
 import Utility.DirWatcher
 import Utility.DirWatcher.Types
 import Config.Files
+import qualified Utility.Lsof as Lsof
+import Utility.ThreadScheduler
+import Assistant.Types.UrlRenderer
+import Assistant.Alert
+import Assistant.DaemonStatus
+#ifdef WITH_WEBAPP
+import Assistant.WebApp.Types
+#endif
 
 import Control.Concurrent.MVar
+import Data.Tuple.Utils
+import qualified Data.Text as T
 
 data WatcherState = InStartupScan | Started | Upgrading
 	deriving (Eq)
 
-upgradWatcherThread :: NamedThread
-upgradWatcherThread = namedThread "UpgradeWatcher" $ go =<< liftIO programPath
+upgradWatcherThread :: UrlRenderer -> NamedThread
+upgradWatcherThread urlrenderer = namedThread "UpgradeWatcher" $ go =<< liftIO programPath
   where
 	go Nothing = debug [ "cannot determine program path" ]
 	go (Just program) = do
 		mvar <- liftIO $ newMVar InStartupScan
-		changed <- Just <$> asIO2 (changedFile mvar program)
+		changed <- Just <$> asIO2 (changedFile urlrenderer mvar program)
 		let hooks = mkWatchHooks
 			{ addHook = changed
 			, addSymlinkHook = changed
@@ -42,10 +54,44 @@ upgradWatcherThread = namedThread "UpgradeWatcher" $ go =<< liftIO programPath
 		void $ swapMVar mvar Started
 		return r
 
-changedFile :: MVar WatcherState -> FilePath -> FilePath -> Maybe FileStatus -> Assistant ()
-changedFile mvar program file _status
-	| program == file = do
+changedFile :: UrlRenderer -> MVar WatcherState -> FilePath -> FilePath -> Maybe FileStatus -> Assistant ()
+changedFile urlrenderer mvar program file _status
+	| program /= file = noop
+	| otherwise = do
 		state <- liftIO $ readMVar mvar
-		when (state == Started) $
-			debug [ "saw change to", file ]
-	| otherwise = noop
+		when (state == Started) $ do
+			setstate Upgrading
+			ifM (sanityCheck program)
+				( handleUpgrade urlrenderer
+				, do
+					debug ["new version of", program, "failed sanity check; not using"]
+					setstate Started
+				)
+  where
+	setstate = void . liftIO . swapMVar mvar
+
+{- The program's file has been changed. Before restarting,
+ - it needs to not be open for write by anything, and should run
+ - successfully when run with the parameter "version".
+ -}
+sanityCheck :: FilePath -> Assistant Bool
+sanityCheck program = do
+	whileM (liftIO haswriter) $ do
+		debug [program, "is still being written; waiting"]
+		liftIO $ threadDelaySeconds (Seconds 60)
+	debug [program, "has changed, and seems to be ready to run"]
+	liftIO $ boolSystem program [Param "version"]
+  where
+	haswriter = not . null
+		. filter (`elem` [Lsof.OpenReadWrite, Lsof.OpenWriteOnly])
+		. map snd3
+		<$> Lsof.query [program]
+
+handleUpgrade :: UrlRenderer -> Assistant ()
+handleUpgrade urlrenderer = do
+#ifdef WITH_WEBAPP
+	button <- mkAlertButton True (T.pack "Finish Upgrade") urlrenderer ConfigFinishUpgradeR
+	void $ addAlert (upgradeReadyAlert button)
+#else
+	noop
+#endif
-- 
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