ENH Write out log to .failed files

ChangeLog

@@ -9,6 +9,7 @@ Unreleased
 	* Add `names()` method to readset
 	* Add ``println()`` function
 	* Make ``print()`` accept ints and doubles as well as strings
+	* Write log to .failed files when using the parallel module
 
 Version 1.4.2 2022-07-21 by luispedro
 	* Fix bug with parsing GFF files

NGLess/Output.hs

@@ -15,11 +15,12 @@ module Output
     , outputMappedSetStatistics
     , writeOutputJS
     , writeOutputTSV
+    , writeOutputTo
     , outputConfiguration
     ) where
 
 import           Text.Printf (printf)
-import           System.IO (hPutStrLn, hIsTerminalDevice, stdout, stderr)
+import           System.IO (hPutStrLn, hIsTerminalDevice, stdout, stderr, Handle)
 import           System.IO.Unsafe (unsafePerformIO)
 import           System.IO.SafeWrite (withOutputFile)
 import           Data.Maybe (maybeToList, fromMaybe, isJust)
@@ -292,6 +293,17 @@ wrapScript script tags stats = first annotate <$> script
             | i `elem` stats = Just (HasStatsInfo i)
             | otherwise =  Nothing
 
+writeOutputTo :: Handle -> IO ()
+writeOutputTo h = do
+    SavedOutput fullOutput _ _ <- outputReverse <$> readIORef savedOutput
+    forM_ fullOutput $ \(OutputLine lno ot t' msg) -> do
+        let tformat = "%a %d-%m-%Y %T"
+            tstr = formatTime defaultTimeLocale tformat t'
+            lineStr = if lno > 0
+                            then printf " Line %s" (show lno)
+                            else "" :: String
+        hPutStrLn h $ printf "[%s]%s (%s): %s" tstr lineStr (show ot) msg
+
 writeOutputJS :: FilePath -> FilePath -> T.Text -> NGLessIO ()
 writeOutputJS odir scriptName script = liftIO $ do
     SavedOutput fullOutput fqStats mapStats <- outputReverse <$> readIORef savedOutput

NGLess/StandardModules/Parallel.hs

@@ -151,8 +151,9 @@ executeLock1OrForAll funcname (NGOList entries) kwargs  = do
         release rk
     registerFailHook $ do
         let logfile = lockdir </> T.unpack e ++ ".failed"
-        withFile logfile WriteMode $ \h ->
-            hPutStrLn h "Execution failed" -- TODO output log here
+        withFile logfile WriteMode $ \h -> do
+            hPutStrLn h "Execution failed. Execution log:"
+            writeOutputTo h
     case entries of
         (NGOString _:_) -> return . NGOString $! fromMaybe e $ lookup e (zip saneentries entries')
         _ -> case lookup e (zip saneentries entries) of

docs/sources/whatsnew.rst

@@ -19,6 +19,7 @@ which will print ``my-sample``.
 - Make ``print()`` accept ints and doubles as well as strings
 - Added ``println`` function which works like ``print`` but prints a newline after the output.
 - Added ``run_for_all`` function to ``parallel`` module, simplifying its `API <stdlib.html>`__.
+- When using the ``parallel`` module and a job fails, writes the log to the corresponding ``.failed`` file
 
 Version 1.4.2
 -------------