Linux/OSX: Shutdown gracefully on receiving interrupt or terminate signals

src/calibre/gui2/__init__.py

@@ -1,13 +1,13 @@
 __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 """ The GUI """
-import os, sys, Queue, threading, glob
+import os, sys, Queue, threading, glob, signal
 from contextlib import contextmanager
 from threading import RLock, Lock
 from urllib import unquote
 from PyQt5.QtWidgets import QStyle  # Gives a nicer error message than import from Qt
 from PyQt5.Qt import (
-    QFileInfo, QObject, QBuffer, Qt, QByteArray, QTranslator,
+    QFileInfo, QObject, QBuffer, Qt, QByteArray, QTranslator, QSocketNotifier,
     QCoreApplication, QThread, QEvent, QTimer, pyqtSignal, QDateTime,
     QDesktopServices, QFileDialog, QFileIconProvider, QSettings, QIcon,
     QApplication, QDialog, QUrl, QFont, QFontDatabase, QLocale, QFontInfo)
@@ -860,6 +860,8 @@ def setup_gui_option_parser(parser):
 
 class Application(QApplication):
 
+    shutdown_signal_received = pyqtSignal()
+
     def __init__(self, args, force_calibre_style=False, override_program_name=None, headless=False, color_prefs=gprefs):
         self.file_event_hook = None
         if override_program_name:
@@ -872,6 +874,8 @@ class Application(QApplication):
         qargs = [i.encode('utf-8') if isinstance(i, unicode) else i for i in args]
         self.pi = plugins['progress_indicator'][0]
         QApplication.__init__(self, qargs)
+        if not iswindows:
+            self.setup_unix_signals()
         if islinux or isbsd:
             self.setAttribute(Qt.AA_DontUseNativeMenuBar, 'CALIBRE_NO_NATIVE_MENUBAR' in os.environ)
         self.setup_styles(force_calibre_style)
@@ -1048,6 +1052,28 @@ class Application(QApplication):
     def __exit__(self, *args):
         self.setQuitOnLastWindowClosed(True)
 
+    def setup_unix_signals(self):
+        import fcntl
+        read_fd, write_fd = os.pipe()
+        cloexec_flag = getattr(fcntl, 'FD_CLOEXEC', 1)
+        for fd in (read_fd, write_fd):
+            flags = fcntl.fcntl(fd, fcntl.F_GETFD)
+            fcntl.fcntl(fd, fcntl.F_SETFD, flags | cloexec_flag | os.O_NONBLOCK)
+        for sig in (signal.SIGINT, signal.SIGTERM):
+            signal.signal(sig, lambda x, y: None)
+            signal.siginterrupt(sig, False)
+        signal.set_wakeup_fd(write_fd)
+        self.signal_notifier = QSocketNotifier(read_fd, QSocketNotifier.Read, self)
+        self.signal_notifier.setEnabled(True)
+        self.signal_notifier.activated.connect(self.signal_received, type=Qt.QueuedConnection)
+
+    def signal_received(self, read_fd):
+        try:
+            os.read(read_fd, 1024)
+        except EnvironmentError:
+            return
+        self.shutdown_signal_received.emit()
+
 _store_app = None
 
 @contextmanager

src/calibre/gui2/main_window.py

@@ -86,7 +86,6 @@ class MainWindow(QMainWindow):
     ___menu     = None
     __actions   = []
 
-    keyboard_interrupt = pyqtSignal()
     # See https://bugreports.qt-project.org/browse/QTBUG-42281
     window_blocked = pyqtSignal()
     window_unblocked = pyqtSignal()
@@ -131,8 +130,7 @@ class MainWindow(QMainWindow):
         sys.excepthook = ExceptionHandler(self)
 
     def unhandled_exception(self, type, value, tb):
-        if type == KeyboardInterrupt:
-            self.keyboard_interrupt.emit()
+        if type is KeyboardInterrupt:
             return
         try:
             sio = StringIO.StringIO()

src/calibre/gui2/tweak_book/completion/worker.py

@@ -178,7 +178,7 @@ def main(control_conn, data_conn):
     while True:
         try:
             request = eintr_retry_call(control_conn.recv)
-        except EOFError:
+        except (KeyboardInterrupt, EOFError):
             break
         if request is None:
             break

src/calibre/gui2/tweak_book/main.py

@@ -71,6 +71,7 @@ def _run(args, notify=None):
     main = Main(opts, notify=notify)
     main.set_exception_handler()
     main.show()
+    app.shutdown_signal_received.connect(main.boss.quit)
     if len(args) > 1:
         main.boss.open_book(args[1], edit_file=args[2:], clear_notify_data=False)
     else:

src/calibre/gui2/ui.py

@@ -397,8 +397,6 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
         if config['autolaunch_server']:
             self.start_content_server()
 
-        self.keyboard_interrupt.connect(self.quit, type=Qt.QueuedConnection)
-
         self.read_settings()
         self.finalize_layout()
         if self.bars_manager.showing_donate:
@@ -425,6 +423,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
         # Collect cycles now
         gc.collect()
 
+        QApplication.instance().shutdown_signal_received.connect(self.quit)
         if show_gui and self.gui_debug is not None:
             QTimer.singleShot(10, self.show_gui_debug_msg)
 
@@ -843,6 +842,8 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
 
     def quit(self, checked=True, restart=False, debug_on_restart=False,
             confirm_quit=True):
+        if self.shutting_down:
+            return
         if confirm_quit and not self.confirm_quit():
             return
         try:

src/calibre/gui2/viewer/main.py

@@ -178,6 +178,7 @@ class EbookViewer(MainWindow):
         self.action_reload = QAction(_('&Reload book'), self)
         self.action_reload.triggered.connect(self.reload_book)
         self.action_quit.triggered.connect(self.quit)
+        QApplication.instance().shutdown_signal_received.connect(self.action_quit.trigger)
         self.action_reference_mode.triggered[bool].connect(self.view.reference_mode)
         self.action_metadata.triggered[bool].connect(self.metadata.setVisible)
         self.action_table_of_contents.toggled[bool].connect(self.set_toc_visible)

src/calibre/utils/ipc/pool.py

@@ -337,6 +337,8 @@ def worker_main(conn):
             job = cPickle.loads(eintr_retry_call(conn.recv_bytes))
         except EOFError:
             break
+        except KeyboardInterrupt:
+            break
         except Exception:
             prints('recv() failed in worker, terminating worker', file=sys.stderr)
             import traceback

src/calibre/utils/ipc/simple_worker.py

@@ -70,6 +70,8 @@ class OffloadWorker(object):
     def shutdown(self):
         try:
             eintr_retry_call(self.conn.send, None)
+        except IOError:
+            pass
         except:
             import traceback
             traceback.print_exc()