Run debug device detection on the gui thread, with proper handling of startup() and shutdown(). Also refuse to run if a device is already detected.

src/calibre/devices/__init__.py

@@ -55,7 +55,7 @@ def get_connected_device():
             break
     return dev
 
-def debug(ioreg_to_tmp=False, buf=None):
+def debug(ioreg_to_tmp=False, buf=None, plugins=None):
     import textwrap
     from calibre.customize.ui import device_plugins
     from calibre.devices.scanner import DeviceScanner, win_pnp_drives
@@ -66,9 +66,19 @@ def debug(ioreg_to_tmp=False, buf=None):
     if buf is None:
         buf = StringIO()
     sys.stdout = sys.stderr = buf
+    out = partial(prints, file=buf)
+
+    devplugins = device_plugins() if plugins is None else plugins
+    devplugins = list(sorted(devplugins, cmp=lambda
+            x,y:cmp(x.__class__.__name__, y.__class__.__name__)))
+    if plugins is None:
+        for d in devplugins:
+            try:
+                d.startup()
+            except:
+                out('Startup failed for device plugin: %s'%d)
 
     try:
-        out = partial(prints, file=buf)
         out('Version:', __version__)
         s = DeviceScanner()
         s.scan()
@@ -96,8 +106,6 @@ def debug(ioreg_to_tmp=False, buf=None):
             ioreg += 'Output from osx_get_usb_drives:\n'+drives+'\n\n'
             ioreg += Device.run_ioreg()
         connected_devices = []
-        devplugins = list(sorted(device_plugins(), cmp=lambda
-                x,y:cmp(x.__class__.__name__, y.__class__.__name__)))
         out('Available plugins:', textwrap.fill(' '.join([x.__class__.__name__ for x in
             devplugins])))
         out(' ')
@@ -155,6 +163,12 @@ def debug(ioreg_to_tmp=False, buf=None):
     finally:
         sys.stdout = oldo
         sys.stderr = olde
+        if plugins is None:
+            for d in devplugins:
+                try:
+                    d.shutdown()
+                except:
+                    pass
 
 def device_info(ioreg_to_tmp=False, buf=None):
     from calibre.devices.scanner import DeviceScanner, win_pnp_drives

src/calibre/gui2/device.py

@@ -3,7 +3,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 
 # Imports {{{
-import os, traceback, Queue, time, cStringIO, re, sys
+import os, traceback, Queue, time, cStringIO, re, sys, weakref
 from threading import Thread, Event
 
 from PyQt4.Qt import (QMenu, QAction, QActionGroup, QIcon, SIGNAL,
@@ -369,6 +369,18 @@ class DeviceManager(Thread): # {{{
         except:
             return False
 
+    def _debug_detection(self):
+        from calibre.devices import debug
+        raw = debug(plugins=self.devices)
+        return raw
+
+    def debug_detection(self, done):
+        if self.is_device_connected:
+            raise ValueError('Device is currently detected in calibre, cannot'
+                    ' debug device detection')
+        self.create_job(self._debug_detection, done,
+                _('Debug device detection'))
+
     def _get_device_information(self):
         info = self.device.get_device_information(end_session=False)
         if len(info) < 5:
@@ -771,6 +783,15 @@ class DeviceMixin(object): # {{{
         if tweaks['auto_connect_to_folder']:
             self.connect_to_folder_named(tweaks['auto_connect_to_folder'])
 
+    def debug_detection(self, done):
+        self.debug_detection_callback = weakref.ref(done)
+        self.device_manager.debug_detection(FunctionDispatcher(self.debug_detection_done))
+
+    def debug_detection_done(self, job):
+        d = self.debug_detection_callback()
+        if d is not None:
+            d(job)
+
     def show_open_feedback(self, devname, e):
         try:
             self.__of_dev_mem__ = d = e.custom_dialog(self)

src/calibre/gui2/preferences/device_debug.py

@@ -10,15 +10,18 @@ __docformat__ = 'restructuredtext en'
 from PyQt4.Qt import QDialog, QVBoxLayout, QPlainTextEdit, QTimer, \
     QDialogButtonBox, QPushButton, QApplication, QIcon
 
+from calibre.gui2 import error_dialog
+
 class DebugDevice(QDialog):
 
-    def __init__(self, parent=None):
+    def __init__(self, gui, parent=None):
         QDialog.__init__(self, parent)
+        self.gui = gui
         self._layout = QVBoxLayout(self)
         self.setLayout(self._layout)
         self.log = QPlainTextEdit(self)
         self._layout.addWidget(self.log)
-        self.log.setPlainText(_('Getting debug information')+'...')
+        self.log.setPlainText(_('Getting debug information, please wait')+'...')
         self.copy = QPushButton(_('Copy to &clipboard'))
         self.copy.setDefault(True)
         self.setWindowTitle(_('Debug device detection'))
@@ -36,12 +39,26 @@ class DebugDevice(QDialog):
         QTimer.singleShot(1000, self.debug)
 
     def debug(self):
-        try:
-            from calibre.devices import debug
-            raw = debug()
-            self.log.setPlainText(raw)
-        finally:
+        if self.gui.device_manager.is_device_connected:
+            error_dialog(self, _('Device already detected'),
+                    _('A device (%s) is already detected by calibre.'
+                        ' If you wish to debug the detection of another device'
+                        ', first disconnect this device.')%
+                    self.gui.device_manager.connected_device.get_gui_name(),
+                    show=True)
             self.bbox.setEnabled(True)
+            return
+        self.gui.debug_detection(self)
+
+    def __call__(self, job):
+        if not self.isVisible(): return
+        self.bbox.setEnabled(True)
+        if job.failed:
+            return error_dialog(self, _('Debugging failed'),
+                    _('Running debug device detection failed. Click Show '
+                        'Details for more information.'), det_msg=job.details,
+                    show=True)
+        self.log.setPlainText(job.result)
 
     def copy_to_clipboard(self):
         QApplication.clipboard().setText(self.log.toPlainText())

src/calibre/gui2/preferences/misc.py

@@ -52,7 +52,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
 
     def debug_device_detection(self, *args):
         from calibre.gui2.preferences.device_debug import DebugDevice
-        d = DebugDevice(self)
+        d = DebugDevice(self.gui, self)
         d.exec_()
 
     def user_defined_device(self, *args):