From 3240c330c1c6473ab0cb69c0b07ad22d44192396 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 15 Jan 2010 20:24:40 -0700
Subject: [PATCH] Windows device detection: Don't do expensive polling while
 waiting for device disconnect

---
 src/calibre/devices/interface.py | 10 ++++++----
 src/calibre/devices/scanner.py   |  7 +++++--
 src/calibre/gui2/device.py       |  3 ++-
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/calibre/devices/interface.py b/src/calibre/devices/interface.py
index 3d75f0ae22..092f4cb5cd 100644
--- a/src/calibre/devices/interface.py
+++ b/src/calibre/devices/interface.py
@@ -60,7 +60,8 @@ class DevicePlugin(Plugin):
             import traceback
             traceback.print_exc()
 
-    def is_usb_connected_windows(self, devices_on_system, debug=False):
+    def is_usb_connected_windows(self, devices_on_system, debug=False,
+            only_presence=False):
 
         def id_iterator():
             if hasattr(self.VENDOR_ID, 'keys'):
@@ -85,7 +86,7 @@ class DevicePlugin(Plugin):
                    self.test_bcd_windows(device_id, bcd):
                        if debug:
                            self.print_usb_device_info(device_id)
-                       if self.can_handle_windows(device_id, debug=debug):
+                       if only_presence or self.can_handle_windows(device_id, debug=debug):
                            return True
         return False
 
@@ -97,7 +98,8 @@ class DevicePlugin(Plugin):
                 return True
         return False
 
-    def is_usb_connected(self, devices_on_system, debug=False):
+    def is_usb_connected(self, devices_on_system, debug=False,
+            only_presence=False):
         '''
         Return True, device_info if a device handled by this plugin is currently connected.
 
@@ -105,7 +107,7 @@ class DevicePlugin(Plugin):
         '''
         if iswindows:
             return self.is_usb_connected_windows(devices_on_system,
-                    debug=debug), None
+                    debug=debug, only_presence=only_presence), None
 
         vendors_on_system = set([x[0] for x in devices_on_system])
         vendors = self.VENDOR_ID if hasattr(self.VENDOR_ID, '__len__') else [self.VENDOR_ID]
diff --git a/src/calibre/devices/scanner.py b/src/calibre/devices/scanner.py
index 70d44dc767..c47bdfb6fa 100644
--- a/src/calibre/devices/scanner.py
+++ b/src/calibre/devices/scanner.py
@@ -139,8 +139,11 @@ class DeviceScanner(object):
         '''Fetch list of connected USB devices from operating system'''
         self.devices = self.scanner()
 
-    def is_device_connected(self, device, debug=False):
-        return device.is_usb_connected(self.devices, debug=debug)
+    def is_device_connected(self, device, debug=False, only_presence=False):
+        ''' If only_presence is True don't perform any expensive checks (used
+        only in windows)'''
+        return device.is_usb_connected(self.devices, debug=debug,
+                only_presence=only_presence)
 
 
 def main(args=sys.argv):
diff --git a/src/calibre/gui2/device.py b/src/calibre/gui2/device.py
index 49a341ae14..7c2ff498b8 100644
--- a/src/calibre/gui2/device.py
+++ b/src/calibre/gui2/device.py
@@ -134,7 +134,8 @@ class DeviceManager(Thread):
         self.scanner.scan()
         if self.is_device_connected:
             connected, detected_device = \
-                self.scanner.is_device_connected(self.connected_device)
+                self.scanner.is_device_connected(self.connected_device,
+                        only_presence=True)
             if not connected:
                 self.connected_device_removed()
         else: