Fix #1280040 [[FYI] - Left overs in temp](https://bugs.launchpad.net/calibre/+bug/1280040)

src/calibre/gui2/tweak_book/main.py

@@ -6,7 +6,7 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import sys, os, importlib
+import sys, os, importlib, time
 
 from PyQt4.Qt import QIcon
 
@@ -67,6 +67,12 @@ def _run(args, notify=None):
     if len(args) > 1:
         main.boss.open_book(args[1], edit_file=opts.edit_file, clear_notify_data=False)
     app.exec_()
+    # Ensure that the parse worker has quit so that temp files can be deleted
+    # on windows
+    st = time.time()
+    from calibre.gui2.tweak_book.preview import parse_worker
+    while parse_worker.is_alive() and time.time() - st < 120:
+        time.sleep(0.1)
 
 def main(args=sys.argv):
     _run(args)

src/calibre/gui2/tweak_book/preview.py

@@ -155,6 +155,9 @@ class ParseWorker(Thread):
     def clear(self):
         self.parse_items.clear()
 
+    def is_alive(self):
+        return Thread.is_alive(self) or self.worker.is_alive()
+
 parse_worker = ParseWorker()
 # }}}
 

src/calibre/utils/ipc/simple_worker.py

@@ -58,6 +58,8 @@ class OffloadWorker(object):
         self.listener = listener
         self.worker = worker
         self.conn = None
+        self.kill_thread = t = Thread(target=self.worker.kill)
+        t.daemon = True
 
     def __call__(self, module, func, *args, **kwargs):
         if self.conn is None:
@@ -73,13 +75,14 @@ class OffloadWorker(object):
             traceback.print_exc()
         finally:
             self.conn = None
-            t = Thread(target=self.worker.kill)
-            t.daemon = True
             try:
                 os.remove(self.worker.log_path)
             except:
                 pass
-            t.start()
+            self.kill_thread.start()
+
+    def is_alive(self):
+        return self.worker.is_alive or self.kill_thread.is_alive()
 
 def communicate(ans, worker, listener, args, timeout=300, heartbeat=None,
         abort=None):