Fix regression in 0.8.33 that caused calibre to crash when starting the Content Server, if the port the content server is trying to listen on is blocked/busy. Fixes #910512 (calibre crashs after start without message)

src/calibre/gui2/preferences/server.py

@@ -63,9 +63,12 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
 
     def start_server(self):
         ConfigWidgetBase.commit(self)
+        self.setCursor(Qt.BusyCursor)
+        try:
             self.gui.start_content_server(check_started=False)
-        while not self.gui.content_server.is_running and self.gui.content_server.exception is None:
-            time.sleep(1)
+            while (not self.gui.content_server.is_running and
+                    self.gui.content_server.exception is None):
+                time.sleep(0.1)
             if self.gui.content_server.exception is not None:
                 error_dialog(self, _('Failed to start content server'),
                         as_unicode(self.gui.content_server.exception)).exec_()
@@ -73,6 +76,8 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
             self.start_button.setEnabled(False)
             self.test_button.setEnabled(True)
             self.stop_button.setEnabled(True)
+        finally:
+            self.unsetCursor()
 
     def stop_server(self):
         self.gui.content_server.threaded_exit()

src/calibre/gui2/ui.py

@@ -368,9 +368,14 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin, # {{{
                 self.library_view.model().db, server_config().parse())
         self.content_server.state_callback = Dispatcher(
                 self.iactions['Connect Share'].content_server_state_changed)
-        self.content_server.state_callback(True)
         if check_started:
-            QTimer.singleShot(10000, self.test_server)
+            self.content_server.start_failure_callback = \
+                Dispatcher(self.content_server_start_failed)
+
+    def content_server_start_failed(self, msg):
+        error_dialog(self, _('Failed to start Content Server'),
+                _('Could not start the content server. Error:\n\n%s')%msg,
+                show=True)
 
     def resizeEvent(self, ev):
         MainWindow.resizeEvent(self, ev)

src/calibre/library/server/base.py

@@ -26,7 +26,7 @@ from calibre.library.server.cache import Cache
 from calibre.library.server.browse import BrowseServer
 from calibre.library.server.ajax import AjaxServer
 from calibre.utils.search_query_parser import saved_searches
-from calibre import prints
+from calibre import prints, as_unicode
 
 
 class DispatchController(object): # {{{
@@ -112,6 +112,7 @@ class LibraryServer(ContentServer, MobileServer, XMLServer, OPDSServer, Cache,
         self.opts = opts
         self.embedded = embedded
         self.state_callback = None
+        self.start_failure_callback = None
         try:
             self.max_cover_width, self.max_cover_height = \
                         map(int, self.opts.max_cover.split('x'))
@@ -225,10 +226,7 @@ class LibraryServer(ContentServer, MobileServer, XMLServer, OPDSServer, Cache,
         h.setFormatter(cherrypy._cplogging.logfmt)
         log.access_log.addHandler(h)
 
-    def start(self):
-        self.is_running = False
-        cherrypy.tree.mount(root=None, config=self.config)
-        try:
+    def start_cherrypy(self):
         try:
             cherrypy.engine.start()
         except:
@@ -244,17 +242,36 @@ class LibraryServer(ContentServer, MobileServer, XMLServer, OPDSServer, Cache,
 
             cherrypy.engine.start()
 
-            self.is_running = True
-            #if hasattr(cherrypy.engine, 'signal_handler'):
-            #    cherrypy.engine.signal_handler.subscribe()
-
-            cherrypy.engine.block()
+    def start(self):
+        self.is_running = False
+        self.exception = None
+        cherrypy.tree.mount(root=None, config=self.config)
+        try:
+            self.start_cherrypy()
         except Exception as e:
             self.exception = e
             import traceback
             traceback.print_exc()
+            if callable(self.start_failure_callback):
+                try:
+                    self.start_failure_callback(as_unicode(e))
+                except:
+                    pass
+            return
+
+        try:
+            self.is_running = True
+            self.notify_listener()
+            cherrypy.engine.block()
+        except Exception as e:
+            import traceback
+            traceback.print_exc()
+            self.exception = e
         finally:
             self.is_running = False
+            self.notify_listener()
+
+    def notify_listener(self):
         try:
             if callable(self.state_callback):
                 self.state_callback(self.is_running)
@@ -267,11 +284,7 @@ class LibraryServer(ContentServer, MobileServer, XMLServer, OPDSServer, Cache,
         finally:
             cherrypy.server.httpserver = None
             self.is_running = False
-            try:
-                if callable(self.state_callback):
-                    self.state_callback(self.is_running)
-            except:
-                pass
+            self.notify_listener()
 
     def threaded_exit(self):
         from threading import Thread

src/cherrypy/process/wspbus.py

@@ -268,7 +268,11 @@ class Bus(object):
             # Assume it's been logged and just die.
             os._exit(70) # EX_SOFTWARE
 
-        if exitstate == states.STARTING:
+        # Changed by Kovid, we cannot have all of calibre being quit
+        # Also we want to catch the port blocked/busy error and try listening only on
+        # the external ip
+        # See https://bitbucket.org/cherrypy/cherrypy/issue/1017/exit-behavior-is-not-good-when-running-in
+        if False and exitstate == states.STARTING:
             # exit() was called before start() finished, possibly due to
             # Ctrl-C because a start listener got stuck. In this case,
             # we could get stuck in a loop where Ctrl-C never exits the