consistency policy for DB mtimes (#227)

beets/library.py

@@ -131,6 +131,7 @@ class Item(object):
             'album_id': None,
         })
         i.read(path)
+        i.mtime = i.current_mtime() # Initial mtime.
         return i
 
     def _fill_record(self, values):
@@ -177,10 +178,12 @@ class Item(object):
                 value = str(value)
 
         if key in ITEM_KEYS:
+            # If the value changed, mark the field as dirty.
             if (not (key in self.record)) or (self.record[key] != value):
-                # don't dirty if value unchanged
                 self.record[key] = value
                 self.dirty[key] = True
+                if key in ITEM_KEYS_WRITABLE:
+                    self.mtime = 0 # Reset mtime on dirty.
         else:
             super(Item, self).__setattr__(key, value)
     

test/test_db.py

@@ -20,6 +20,7 @@ import os
 import sqlite3
 import ntpath
 import posixpath
+import shutil
 
 import _common
 from _common import item
@@ -653,6 +654,38 @@ class PathStringTest(unittest.TestCase):
         alb = self.lib.get_album(alb.id)
         self.assert_(isinstance(alb.artpath, str))
 
+class MtimeTest(unittest.TestCase):
+    def setUp(self):
+        self.ipath = os.path.join(_common.RSRC, 'testfile.mp3')
+        shutil.copy(os.path.join(_common.RSRC, 'full.mp3'), self.ipath)
+        self.i = beets.library.Item.from_path(self.ipath)
+        self.lib = beets.library.Library(':memory:')
+        self.lib.add(self.i)
+
+    def tearDown(self):
+        if os.path.exists(self.ipath):
+            os.remove(self.ipath)
+
+    def _mtime(self):
+        return os.path.getmtime(self.ipath)
+
+    def test_mtime_initially_up_to_date(self):
+        self.assertGreaterEqual(self.i.mtime, self._mtime())
+
+    def test_mtime_reset_on_db_modify(self):
+        self.i.title = 'something else'
+        self.assertLess(self.i.mtime, self._mtime())
+
+    def test_mtime_up_to_date_after_write(self):
+        self.i.title = 'something else'
+        self.i.write()
+        self.assertGreaterEqual(self.i.mtime, self._mtime())
+
+    def test_mtime_up_to_date_after_read(self):
+        self.i.title = 'something else'
+        self.i.read()
+        self.assertGreaterEqual(self.i.mtime, self._mtime())
+
 def suite():
     return unittest.TestLoader().loadTestsFromName(__name__)