Clean up unused variables

This just removes a few variables that were unused and makes my linter
happy.

Change-Id: I0bc9fc1474e15801e4df84f78636c96ea1f916ff
xenapi: stop hang during glance download

It seems there are cases when the server gets stuck in a building state
because the download from glance fails, but the nova-compute doesn't
find out.

After some code inspect, a likely cause seems to related to having no
socket timeout inside urllib2 when we download the image from glance. A
workaround for this issue is to configure the default socket timeout as
described here:
http://docs.python.org/3.1/howto/urllib2.html#sockets-and-layers

Fixes bug 1251650
Change-Id: I8b34d95d3524f3825b28e61cbbb59290653d3711
Fix UnboundLocalError in libvirt.driver._close_callback

If for whatever reason _wrapped_conn is None or not equal to the conn
parameter passed to the _close_callback method, the local _error
variable won't be set when calling set_host_enabled and result in an
UnboundLocalError.

Partial-Bug: #1257644

Change-Id: I40855f22d5449f3b3646c90fe2d9a71560eb86c4
Merge "xenapi: stop hang during glance download"
Remove the largely obsolete basepath helper

Now that there is a static method for calculating the path to the
config drive, there was only one user left for basepath, and it was
a special case "no filename" user. So, remove it.

Change-Id: I8f4efe19da41d159e929853a5e757e0e168885d7
Merge "Fix UnboundLocalError in libvirt.driver._close_callback"
Merge "Clean up unused variables"
Merge "Remove the largely obsolete basepath helper"
XenAPI: Speedup host_ref cannot change - get it once

The host we run on is fixed - getting this each time from XAPI
is expensive

Change-Id: Ifee9a778f3ed855ef52b001de3fc2ebbd0b972cf
XenAPI: get_info was very expensive

Getting the whole VM record is expensive and slowed down Tempest tests
significantly.  Replaced with getting each required item.

When getting power state, only need that specific value, so reduce the
calls to get_info too.

Change-Id: I93bcef5b692a531aac41518dc29d5d4f46cded65
XenAPI: Tidy calls to get_all_ref_and_rec

get_all_records is more efficient than getting them individually in the
old get_all_ref_and_rec implementation.

Replaced some cases of get_all_records with a faster and more
specific API call.

Change-Id: I4725c3f1fdebdf1737941cb7db69b19afb22df9f
XenAPI: Speedup get_vhd_parent_uuid

In many cases the VDI record has already been retrieved.
Use it rather than expensively getting a new VDI record from XAPI.

Change-Id: I469e2a415c1f1924010f47d3927ca18c45a7b8f8
XenAPI: Use get_VALUE in preference to get_record()['VALUE']

Replaces calls to get_record where only a single item is retrieved
from the record with the specific get_VALUE call.

Change-Id: I52e20c4f4c9d6a6ad019694916ee057cc96b18a6
XenAPI: Synchronize on all VBD plug/unplug per VM

Dynamically adding or removing a device needs to be synchronized
to work around a bug in XenServer 6.1 and 6.2 where simultaneous
events can be partially ignored, leading to a failure to plug or
unplug.

Change I041365ed863a1a1c55e88025dff42d01c35494a2 attempted to
work around the issue by retrying - however that does not catch
all failures.  This change should eliminate some of the known
INTERNAL_ERROR failures, but not all, so I041 should not be
reverted.

Change Ie7a64c481a9e3874df9d5924fbb050ac7ab117db does the same
as this, but only for VBD.plug.

Change-Id: If78d4e5f1dd84f1d4a588f25b8f887a7b125bbea
Closes-bug: 1217972
XenAPI: Monitor the GC when coalescing

Add a new host plugin to monitor whether the garbage collector is running.
This is then used by the wait_for_vhd_coalesce function to know whether
waiting any more is likely to produce the expected results.

Increased the number of times we loop waiting for coalesce as the loop
now has knowledge that something is still happening.

Change-Id: Idcc0738945bd1aee8cdb52c9cfabd798f85c31db
Closes-bug: 1258169

Conflicts:

	nova/virt/xenapi/vm_utils.py
XenAPI: Use direct IO for writing config drive

If you don't use direct IO when writing to the device, the unplug
immediately following this may not succeed as the device may still
be in use.

Change-Id: I68f09835648b36772a7839af9718123a4c60734f