Add prototype inotify backend

1 files changed, 60 insertions, 0 deletions

diff --git a/src/Hakyll/Web/Preview/INotify.hs b/src/Hakyll/Web/Preview/INotify.hs
new file mode 100644
index 0000000..fb3a7de
--- /dev/null
+++ b/src/Hakyll/Web/Preview/INotify.hs
@@ -0,0 +1,60 @@
+-- | Filesystem polling with an inotify backend. Works only on linux.
+--
+module Hakyll.Web.Preview.INotify
+    ( previewPoll
+    ) where
+
+import Control.Monad (forM_, when, unless)
+import System.Directory (doesDirectoryExist)
+import System.FilePath ((</>))
+import Data.List (isPrefixOf)
+
+import System.INotify
+
+import Hakyll.Core.Util.File
+import Hakyll.Core.Configuration
+
+-- | Calls the given callback when the directory tree changes
+--
+previewPoll :: HakyllConfiguration  -- ^ Configuration
+            -> FilePath             -- ^ Root directory
+            -> IO ()                -- ^ Action called when something changes
+            -> IO ()                -- ^ Can block forever
+previewPoll conf directory callback = do
+    -- Initialize inotify
+    inotify <- initINotify
+
+    -- Start by watching all directories
+    contents <- getRecursiveContents True directory
+    forM_ contents $ \file -> do
+        isDir <- doesDirectoryExist file
+        when isDir $ watchDirectory conf inotify file callback
+
+-- | Start watching a directory recursively: when another directory is created
+-- inside this directory, start watching that one as well...
+--
+watchDirectory :: HakyllConfiguration  -- ^ Configuration
+               -> INotify              -- ^ INotify handle
+               -> FilePath             -- ^ Directory to watch
+               -> IO ()                -- ^ Callback
+               -> IO ()                -- ^ No result
+watchDirectory conf inotify path callback =
+    unless (isFileInternal conf path) $ do
+        _ <- addWatch inotify interesting path $ \event -> do
+            putStrLn $ "Triggered: " ++ show event
+            callback' inotify path event
+        return ()
+  where
+    callback' i p (Created True n) = watchDirectory conf i (p </> n) callback
+    callback' _ _ (Created _ p)    = whenProper $ Just p
+    callback' _ _ (Modified _ p)   = whenProper p
+    callback' _ _ (MovedOut _ p _) = whenProper $ Just p
+    callback' _ _ (MovedIn _ p _)  = whenProper $ Just p
+    callback' _ _ (Deleted _ p)    = whenProper $ Just p
+    callback' _ _ _                = return ()
+
+    interesting = [Modify, Create, Move, Delete]
+
+    -- Call the callback only for proper files
+    whenProper Nothing  = return ()
+    whenProper (Just f) = unless ("." `isPrefixOf` f) callback