dirstate: optimize copied for treestate

Summary:
For treestate, `copies` is more expensive as it's not a cache but calculates
from the source of truth. So avoid using `copies` but read the copy
information directly from the tree.

Reviewed By: DurhamG

Differential Revision: D8595357

fbshipit-source-id: bcea254358d66c9fa9f933d73221bbeb0bd8d5b2

mercurial/dirstate.py

@@ -422,7 +422,10 @@ class dirstate(object):
             self._updatedfiles.add(dest)
 
     def copied(self, file):
-        return self._map.copymap.get(file, None)
+        if self._istreestate:
+            return self._map.copysource(file)
+        else:
+            return self._map.copymap.get(file, None)
 
     def copies(self):
         return self._map.copymap

mercurial/treestate.py

@@ -460,3 +460,14 @@ class treestatemap(object):
             state |= treestate.NEED_CHECK
         self._tree.insert(path, state, mode, size, mtime, copied)
         return True
+
+    def copysource(self, path):
+        """Return the copysource for path. Return None if it's not copied, or
+        path does not exist.
+        """
+        existing = self._tree.get(path, None)
+        if existing:
+            _state, _mode, _size, _mtime, copied = existing
+            return copied
+        else:
+            return None