dirstate: move opendirstatefile to dirstatemap

dirstate: move opendirstatefile to dirstatemap

As part of moving the dirstate storage logic to another class, let's move
opendirstatefile to dirstatemap. This will allow extensions to replace the
pending abstraction.

Future patches will move the consumers of _opendirstatefile into dirstatemap as
well.

Differential Revision: https://phab.mercurial-scm.org/D757

--- a/mercurial/dirstate.py	Tue Sep 26 03:56:20 2017 -0700
+++ b/mercurial/dirstate.py	Tue Sep 26 03:56:20 2017 -0700
@@ -82,9 +82,6 @@
         self._origpl = None
         self._updatedfiles = set()
 
-        # for consistent view between _pl() and _read() invocations
-        self._pendingmode = None
-
     @contextlib.contextmanager
     def parentchange(self):
         '''Context manager for handling dirstate parents.
@@ -190,7 +187,7 @@
     @propertycache
     def _pl(self):
         try:
-            fp = self._opendirstatefile()
+            fp = self._map._opendirstatefile()
             st = fp.read(40)
             fp.close()
             l = len(st)
@@ -401,23 +398,14 @@
             f.discard()
             raise
 
-    def _opendirstatefile(self):
-        fp, mode = txnutil.trypending(self._root, self._opener, self._filename)
-        if self._pendingmode is not None and self._pendingmode != mode:
-            fp.close()
-            raise error.Abort(_('working directory state may be '
-                                'changed parallelly'))
-        self._pendingmode = mode
-        return fp
-
     def _read(self):
-        self._map = dirstatemap()
+        self._map = dirstatemap(self._ui, self._opener, self._root)
 
         # ignore HG_PENDING because identity is used only for writing
         self._identity = util.filestat.frompath(
             self._opener.join(self._filename))
         try:
-            fp = self._opendirstatefile()
+            fp = self._map._opendirstatefile()
             try:
                 st = fp.read()
             finally:
@@ -698,7 +686,7 @@
         return path
 
     def clear(self):
-        self._map = dirstatemap()
+        self._map = dirstatemap(self._ui, self._opener, self._root)
         self._nonnormalset = set()
         self._otherparentset = set()
         if "_dirs" in self.__dict__:
@@ -1308,10 +1296,18 @@
         self._opener.unlink(backupname)
 
 class dirstatemap(object):
-    def __init__(self):
+    def __init__(self, ui, opener, root):
+        self._ui = ui
+        self._opener = opener
+        self._root = root
+        self._filename = 'dirstate'
+
         self._map = {}
         self.copymap = {}
 
+        # for consistent view between _pl() and _read() invocations
+        self._pendingmode = None
+
     def iteritems(self):
         return self._map.iteritems()
 
@@ -1375,3 +1371,13 @@
         current dirstate.
         """
         return util.dirs(self._map, 'r')
+
+    def _opendirstatefile(self):
+        fp, mode = txnutil.trypending(self._root, self._opener, self._filename)
+        if self._pendingmode is not None and self._pendingmode != mode:
+            fp.close()
+            raise error.Abort(_('working directory state may be '
+                                'changed parallelly'))
+        self._pendingmode = mode
+        return fp
+