IGN:Remove uneccessary dependency on Qt mainloop when messaging the GUI from a commandline app

src/calibre/library/cli.py

@@ -11,7 +11,10 @@ import sys, os
 from textwrap import TextWrapper
 
 from calibre import OptionParser, Settings, terminal_controller, preferred_encoding
-from calibre.gui2 import SingleApplication
+try:
+    from calibre.utils.single_qt_application import send_message
+except:
+    send_message = None
 from calibre.ebooks.metadata.meta import get_metadata
 from calibre.ebooks.metadata.opf import OPFCreator, OPFReader
 from calibre.library.database import LibraryDatabase, text_to_tokens
@@ -182,9 +185,8 @@ def do_add(db, paths, one_book_per_directory, recurse, add_duplicates):
                     print '\t', title+':'
                     print '\t\t ', path
         
-        if SingleApplication is not None:
-            sa = SingleApplication('calibre GUI')
-            sa.send_message('refreshdb:')
+        if send_message is not None:
+            send_message('refreshdb:', 'calibre GUI')
     finally:
         sys.stdout = sys.__stdout__
             
@@ -222,9 +224,9 @@ def do_remove(db, ids):
             for y in x:
                 db.delete_book(y)
     
-    if SingleApplication is not None:
-        sa = SingleApplication('calibre GUI')
-        sa.send_message('refreshdb:')
+    if send_message is not None:
+        send_message('refreshdb:', 'calibre GUI')
+    
     
 def command_remove(args, dbpath):
     parser = get_parser(_(
@@ -337,9 +339,8 @@ def do_set_metadata(db, id, stream):
     mi = OPFReader(stream)
     db.set_metadata(id, mi)
     do_show_metadata(db, id, False)
-    if SingleApplication is not None:
-        sa = SingleApplication('calibre GUI')
-        sa.send_message('refreshdb:')
+    if send_message is not None:
+        send_message('refreshdb:', 'calibre GUI')
     
 def command_set_metadata(args, dbpath):
     parser = get_parser(_(

src/calibre/utils/single_qt_application.py

@@ -104,7 +104,12 @@ class LocalServer(QLocalServer):
         return True
         
                 
-        
+def send_message(msg, name, server_name='calibre_server', timeout=5000):
+    socket = QLocalSocket()
+    socket.connectToServer(server_name)
+    if socket.waitForConnected(timeout_connect):
+        if read_message(socket) == name:
+            write_message(socket, name+':'+msg, timeout)
         
 class SingleApplication(QObject):