unused: Improved memory use significantly when there are a lot of differences between branches.

Argh, didn't need an accumulator here!

I think I use accumulators a lot more than I need to when recusively
processing lists..

This commit was sponsored by Jeff Goeke-Smith on Patreon.

CHANGELOG

@@ -11,6 +11,8 @@ git-annex (6.20170102) UNRELEASED; urgency=medium
   * Some optimisations to string splitting code.
   * unused: When large files are checked right into git, avoid buffering
     their contents in memory.
+  * unused: Improved memory use significantly when there are a lot
+    of differences between branches.
 
  -- Joey Hess <id@joeyh.name>  Fri, 06 Jan 2017 15:22:06 -0400
 

Git/DiffTree.hs

@@ -101,11 +101,11 @@ getdiff command params repo = do
 
 {- Parses --raw output used by diff-tree and git-log. -}
 parseDiffRaw :: [String] -> [DiffTreeItem]
-parseDiffRaw l = go l []
+parseDiffRaw l = go l
   where
-	go [] c = c
-	go (info:f:rest) c = go rest (mk info f : c)
-	go (s:[]) _ = error $ "diff-tree parse error near \"" ++ s ++ "\""
+	go [] = []
+	go (info:f:rest) = mk info f : go rest
+	go (s:[]) = error $ "diff-tree parse error near \"" ++ s ++ "\""
 
 	mk info f = DiffTreeItem
 		{ srcmode = readmode srcm

doc/todo/more_efficient_memory_usage_with_git-annex_unused.mdwn

@@ -1,3 +1,6 @@
 While running *git-annex unused* on an annex with tens of thousands of items, *git-annex*'s memory usage ballooned to over 3 gigs and my PC froze. I cannot run *git-annex unused* on this annex because of this issue.
 
 If it's possible, more efficient memory management would prevent this from happening.
+
+> [[done]] -- assuming the memory leak I saw was the same one you saw...
+> --[[Joey]]

doc/todo/more_efficient_memory_usage_with_git-annex_unused/comment_3_3c712e871ea3cd12916497f2d8152004._comment

@@ -0,0 +1,10 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 3"""
+ date="2017-01-31T23:31:03Z"
+ content="""
+Fixed the rest of the streaming problem.
+
+(Also found/fixed an unrelated memory blow up in git annex unused that
+only happened when a large file got checked right into git.)
+"""]]