[commit: ghc] wip/nfs-locking: Add comments. (e2fbf4c)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/nfs-locking
Link       : http://ghc.haskell.org/trac/ghc/changeset/e2fbf4c8b06e6e9692473dca31b390fe30953256/ghc

>---------------------------------------------------------------

commit e2fbf4c8b06e6e9692473dca31b390fe30953256
Author: Andrey Mokhov <andrey.mokhov at gmail.com>
Date:   Fri Feb 26 12:09:40 2016 +0000

    Add comments.
    
    See #210.


>---------------------------------------------------------------

e2fbf4c8b06e6e9692473dca31b390fe30953256
 src/Oracles/ModuleFiles.hs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Oracles/ModuleFiles.hs b/src/Oracles/ModuleFiles.hs
index 508b554..5cb7a5b 100644
--- a/src/Oracles/ModuleFiles.hs
+++ b/src/Oracles/ModuleFiles.hs
@@ -101,6 +101,8 @@ moduleFilesOracle = void $ do
                 ++ f1 ++ " and " ++ f2 ++ "."
         return $ lookupAll modules pairs
 
+    -- Optimisation: we discard .(l)hs files here, because they are never used
+    -- as generators, and hence would be discarded in 'findGenerator' anyway.
     gens <- newCache $ \context -> do
         files <- contextFiles context
         return $ Map.fromList [ (generatedFile context modName, src)