Infrastructure to detect mem leaks in the edit metadata dialog

src/calibre/gui2/actions/edit_metadata.py

@@ -154,15 +154,17 @@ class EditMetadataAction(InterfaceAction):
             d.view_format.connect(lambda
                     fmt:self.gui.iactions['View'].view_format(row_list[current_row],
                         fmt))
-            if d.exec_() != d.Accepted:
-                d.view_format.disconnect()
+            ret = d.exec_()
+            d.break_cycles()
+            if ret != d.Accepted:
                 break
-            d.view_format.disconnect()
+
             changed.add(d.id)
             if d.row_delta == 0:
                 break
             current_row += d.row_delta
 
+
         if changed:
             self.gui.library_view.model().refresh_ids(list(changed))
             current = self.gui.library_view.currentIndex()

src/calibre/gui2/dialogs/metadata_single.py

@@ -293,7 +293,8 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
         finally:
             self.fetch_cover_button.setEnabled(True)
             self.unsetCursor()
-            self.pi.stop()
+            if self.pi is not None:
+                self.pi.stop()
 
 
     # }}}
@@ -442,7 +443,6 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
         ResizableDialog.__init__(self, window)
         self.cover_fetcher = None
         self.bc_box.layout().setAlignment(self.cover, Qt.AlignCenter|Qt.AlignHCenter)
-        self.cancel_all = False
         base = unicode(self.author_sort.toolTip())
         self.ok_aus_tooltip = '<p>' + textwrap.fill(base+'<br><br>'+
                             _(' The green color indicates that the current '
@@ -573,7 +573,6 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
         QObject.connect(self.series, SIGNAL('editTextChanged(QString)'), self.enable_series_index)
         self.series.lineEdit().editingFinished.connect(self.increment_series_index)
 
-        self.show()
         pm = QPixmap()
         if cover:
             pm.loadFromData(cover)
@@ -593,6 +592,8 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
         self.original_author = unicode(self.authors.text()).strip()
         self.original_title = unicode(self.title.text()).strip()
 
+        self.show()
+
     def create_custom_column_editors(self):
         w = self.central_widget.widget(1)
         layout = w.layout()
@@ -907,3 +908,65 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
         dynamic.set('metasingle_window_geometry', bytes(self.saveGeometry()))
         dynamic.set('metasingle_splitter_state',
                 bytes(self.splitter.saveState()))
+
+    def break_cycles(self):
+        try:
+            self.view_format.disconnect()
+        except:
+            pass # Fails if view format was never connected
+        self.view_format = None
+        self.db = None
+        self.pi = None
+        self.cover_data = self.cpixmap = None
+
+if __name__ == '__main__':
+    from calibre.library import db
+    from PyQt4.Qt import QApplication
+    from calibre.utils.mem import memory
+    import gc
+
+
+    app = QApplication([])
+    db = db()
+
+    # Initialize all Qt Objects once
+    d = MetadataSingleDialog(None, 4, db)
+    d.break_cycles()
+    d.reject()
+    del d
+
+    for i in range(3):
+        gc.collect()
+    before = memory()
+
+    gc.collect()
+    d = MetadataSingleDialog(None, 4, db)
+    d.break_cycles()
+    d.reject()
+    del d
+
+    for i in range(3):
+        gc.collect()
+    print 'Used memory:', memory(before)/1024.**2, 'MB'
+    gc.collect()
+
+    '''
+    nmap, omap = {}, {}
+    for x in objects:
+        omap[id(x)] = x
+    for x in nobjects:
+        nmap[id(x)] = x
+
+    new_ids = set(nmap.keys()) - set(omap.keys())
+    print "New ids:", len(new_ids)
+    for i in new_ids:
+        o = nmap[i]
+        if o is objects:
+            continue
+        print repr(o)[:1050]
+        refs = gc.get_referrers(o)
+        for r in refs:
+            if r is objects or r is nobjects:
+                continue
+            print '\t', r
+    '''

src/calibre/utils/mem.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:ai
+
+__license__   = 'GPL v3'
+__copyright__ = '2010, Kovid Goyal <kovid@kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+## {{{ http://code.activestate.com/recipes/286222/ (r1)
+import os
+
+_proc_status = '/proc/%d/status' % os.getpid()
+
+_scale = {'kB': 1024.0, 'mB': 1024.0*1024.0,
+          'KB': 1024.0, 'MB': 1024.0*1024.0}
+
+def _VmB(VmKey):
+    '''Private.
+    '''
+    global _proc_status, _scale
+     # get pseudo file  /proc/<pid>/status
+    try:
+        t = open(_proc_status)
+        v = t.read()
+        t.close()
+    except:
+        return 0.0  # non-Linux?
+     # get VmKey line e.g. 'VmRSS:  9999  kB\n ...'
+    i = v.index(VmKey)
+    v = v[i:].split(None, 3)  # whitespace
+    if len(v) < 3:
+        return 0.0  # invalid format?
+     # convert Vm value to bytes
+    return float(v[1]) * _scale[v[2]]
+
+
+def memory(since=0.0):
+    '''Return memory usage in bytes.
+    '''
+    return _VmB('VmSize:') - since
+
+
+def resident(since=0.0):
+    '''Return resident memory usage in bytes.
+    '''
+    return _VmB('VmRSS:') - since
+
+
+def stacksize(since=0.0):
+    '''Return stack size in bytes.
+    '''
+    return _VmB('VmStk:') - since
+## end of http://code.activestate.com/recipes/286222/ }}}
+
+
+