From c7f386cec0f2de3e4cb64b53b064576494ac711d Mon Sep 17 00:00:00 2001
From: Florian Bruhin <git@the-compiler.org>
Date: Wed, 18 Nov 2015 20:21:23 +0100
Subject: [PATCH] Avoid logging in signal handlers.

If we don't do that, we can get this:

--- Logging error ---
Traceback (most recent call last):
  File ".../python3.5/logging/__init__.py", line 984, in emit
    self.flush()
  File ".../python3.5/logging/__init__.py", line 964, in flush
    self.stream.flush()
RuntimeError: reentrant call inside <_io.BufferedWriter name='<stderr>'>
Call stack:
  [...]
  File ".../qutebrowser/app.py", line 122, in qt_mainloop
    return qApp.exec_()
  File ".../qutebrowser/utils/objreg.py", line 118, in on_destroyed
    log.destroy.debug("schedule removal: {}".format(name))
  File ".../python3.5/logging/__init__.py", line 1267, in debug
    self._log(DEBUG, msg, args, **kwargs)
  File ".../python3.5/logging/__init__.py", line 1415, in _log
    self.handle(record)
  File ".../python3.5/logging/__init__.py", line 1425, in handle
    self.callHandlers(record)
  File ".../python3.5/logging/__init__.py", line 1487, in callHandlers
    hdlr.handle(record)
  File ".../python3.5/logging/__init__.py", line 855, in handle
    self.emit(record)
  File ".../python3.5/logging/__init__.py", line 984, in emit
    self.flush()
  File ".../python3.5/logging/__init__.py", line 964, in flush
    self.stream.flush()
  File ".../qutebrowser/misc/crashsignal.py", line 365, in interrupt
    log.destroy.info("Do the same again to forcefully quit.")
Message: 'Do the same again to forcefully quit.'
Arguments: ()
---
 qutebrowser/misc/crashsignal.py | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/qutebrowser/misc/crashsignal.py b/qutebrowser/misc/crashsignal.py
index 98a74b666..940d23de2 100644
--- a/qutebrowser/misc/crashsignal.py
+++ b/qutebrowser/misc/crashsignal.py
@@ -355,17 +355,23 @@ class SignalHandler(QObject):
             log.destroy.exception("Failed to read wakeup fd.")
         self._notifier.setEnabled(True)
 
+    def _log_later(self, *lines):
+        """Log the given text line-wise with a QTimer."""
+        for line in lines:
+            QTimer.singleShot(0, functools.partial(log.destroy.info, line))
+
     def interrupt(self, signum, _frame):
         """Handler for signals to gracefully shutdown (SIGINT/SIGTERM).
 
         This calls shutdown and remaps the signal to call
         interrupt_forcefully the next time.
         """
-        log.destroy.info("SIGINT/SIGTERM received, shutting down!")
-        log.destroy.info("Do the same again to forcefully quit.")
         signal.signal(signal.SIGINT, self.interrupt_forcefully)
         signal.signal(signal.SIGTERM, self.interrupt_forcefully)
-        # If we call shutdown directly here, we get a segfault.
+        # Signals can arrive anywhere, so we do this in the main thread
+        self._log_later(
+            "SIGINT/SIGTERM received, shutting down!",
+            "Do the same again to forcefully quit.")
         QTimer.singleShot(0, functools.partial(
             self._quitter.shutdown, 128 + signum))
 
@@ -376,12 +382,12 @@ class SignalHandler(QObject):
         It then remaps the signals to call self.interrupt_really_forcefully the
         next time.
         """
-        log.destroy.info("Forceful quit requested, goodbye cruel world!")
-        log.destroy.info("Do the same again to quit with even more force.")
         signal.signal(signal.SIGINT, self.interrupt_really_forcefully)
         signal.signal(signal.SIGTERM, self.interrupt_really_forcefully)
-        # This *should* work without a QTimer, but because of the trouble in
-        # self.interrupt we're better safe than sorry.
+        # Signals can arrive anywhere, so we do this in the main thread
+        self._log_later(
+            "Forceful quit requested, goodbye cruel world!",
+            "Do the same again to quit with even more force.")
         QTimer.singleShot(0, functools.partial(self._app.exit, 128 + signum))
 
     def interrupt_really_forcefully(self, signum, _frame):
@@ -390,5 +396,5 @@ class SignalHandler(QObject):
         This doesn't run *any* Qt cleanup and simply exits via Python.
         It will most likely lead to a segfault.
         """
-        log.destroy.info("WHY ARE YOU DOING THIS TO ME? :(")
+        print("WHY ARE YOU DOING THIS TO ME? :(")
         sys.exit(128 + signum)