fsemulation: set ctime / mtime on object symlinks according to object

Setting ctime and mtime on object symlinks to the values of the object
itself enables sorting directories of symlinks (e.g. by-title)
by time.

1 files changed, 65 insertions, 30 deletions

diff --git a/fsemulation.py b/fsemulation.py
index 5f35bf7..31f9b47 100644
--- a/fsemulation.py
+++ b/fsemulation.py
@@ -462,7 +462,7 @@ class FSEntry(object):
         self._ds = file_system.data_store
         self.mode = mode
 
-    def get_properties(self, names=None):
+    def get_properties(self, names=None, use_cache=False):
         """Read the given properties (default: all)
 
         Returns a dictionary with unicode strings as keys and values.
@@ -549,13 +549,64 @@ class Symlink(FSEntry):
         return 'Symlink(%r, %r)' % (self._fs, self.target)
 
 
-class DSObject(FSEntry):
-    def __init__(self, file_system, object_id):
-        FSEntry.__init__(self, file_system, stat.S_IFREG | 0750)
+class DSObjectBase(FSEntry):
+    def __init__(self, file_system, mode, object_id, metadata=None):
+        FSEntry.__init__(self, file_system, mode)
         self.object_id = object_id
+        self._metadata = metadata
+        self._have_nonstandard = False
+
+    def get_properties(self, names=None, use_cache=False):
+        nonstandard_names = bool([True for name in names
+                                  if name not in _USEFUL_PROPS])
+        if names and not nonstandard_names:
+            fetch_names = names
+        else:
+            fetch_names = None
+        if ((not use_cache) or (self._metadata is None) or
+            (nonstandard_names and not self._have_nonstandard)):
+            self._metadata = self._ds.get_properties(self.object_id,
+                                                     fetch_names)
+            self._have_nonstandard = nonstandard_names
+
+        if not names:
+            return self._metadata
+        return dict([(name, self._metadata[name])
+                     for name in names
+                     if name in self._metadata])
+
+    def get_ctime(self):
+        props = self.get_properties([u'creation_time', u'timestamp'])
+        try:
+            return float(props[u'creation_time'])
+        except (KeyError, ValueError, TypeError):
+            pass
+
+        try:
+            return float(props[u'timestamp'])
+        except (KeyError, ValueError, TypeError):
+            return time.time()
+
+    def get_mtime(self):
+        props = self.get_properties([u'creation_time', u'timestamp'])
+        try:
+            return float(props[u'timestamp'])
+        except (KeyError, ValueError, TypeError):
+            return time.time()
+
+
+class ObjectSymlink(Symlink, DSObjectBase):
+    def __init__(self, file_system, target, object_id, metadata=None):
+        assert isinstance(target, unicode)
+        DSObjectBase.__init__(self, file_system, stat.S_IFLNK | 0777,
+                              object_id, metadata)
+        self.target = target
+
 
-    def get_properties(self, names=None):
-        return self._ds.get_properties(self.object_id, names)
+class DSObject(DSObjectBase):
+    def __init__(self, file_system, object_id, metadata=None):
+        DSObjectBase.__init__(self, file_system, stat.S_IFREG | 0750,
+                              object_id, metadata)
 
     def list_properties(self):
         return self._ds.list_properties(self.object_id)
@@ -584,25 +635,6 @@ class DSObject(FSEntry):
     def get_size(self):
         return self._ds.get_size(self.object_id)
 
-    def get_ctime(self):
-        props = self.get_properties([u'creation_time', u'timestamp'])
-        try:
-            return float(props[u'creation_time'])
-        except (KeyError, ValueError, TypeError):
-            pass
-
-        try:
-            return float(props[u'timestamp'])
-        except (KeyError, ValueError, TypeError):
-            return time.time()
-
-    def get_mtime(self):
-        props = self.get_properties([u'creation_time', u'timestamp'])
-        try:
-            return float(props[u'timestamp'])
-        except (KeyError, ValueError, TypeError):
-            return time.time()
-
 
 class Directory(FSEntry):
     def __init__(self, file_system, level, mode, parent=None):
@@ -619,15 +651,18 @@ class Directory(FSEntry):
         if self.parent is not None:
             yield (u'..', self.parent)
 
-    def _get_symlink(self, object_id):
+    def _get_symlink(self, object_id, metadata=None):
         directory_path = u'../' * self._level + u'by-id/'
         if isinstance(object_id, tuple):
             assert (isinstance(object_id[0], unicode) and
                     isinstance(object_id[1], unicode))
-            return Symlink(self._fs, directory_path + u'/'.join(object_id))
+            return ObjectSymlink(self._fs,
+                                 directory_path + u'/'.join(object_id),
+                                 object_id, metadata)
         else:
             assert isinstance(object_id, unicode)
-            return Symlink(self._fs, directory_path + object_id)
+            return ObjectSymlink(self._fs, directory_path + object_id,
+                                 object_id, metadata)
 
 
 class ByTitleDirectory(Directory):
@@ -648,7 +683,7 @@ class ByTitleDirectory(Directory):
 
         for object_id, metadata in self._ds.list_metadata():
             name = self._fs.lookup_title_name(object_id, metadata)
-            yield (name, self._get_symlink(object_id))
+            yield (name, self._get_symlink(object_id, metadata))
 
     def lookup(self, name):
         object_id = self._fs.resolve_title_name(name)
@@ -766,7 +801,7 @@ class ByTagsSubDirectory(ByTitleDirectory):
 
         for object_id, metadata in self._find_entries():
             name = self._fs.lookup_title_name(object_id, metadata)
-            yield (name, self._get_symlink(object_id))
+            yield (name, self._get_symlink(object_id, metadata))
 
     def _find_entries(self):
         query = {'query': ' '.join(self._tags)}