Use single connection in get_all function for getting "enabled" values for all ldap users.

[Min Song]

LDAP being enabled, any keystone commands that use get_all takes a lot of time, especially if there are many LDAP users (like ~3000), due to the fact that _get_enabled makes a new connection for each user. Instead, I thought it would be better if a connection is made before the for loop in get_all, get all "enabled" values from all users, and then close the connection. I actually tested this code change on mine, and it actually speeds up many keystone commands (user-list, user-role-add, user-delete, user-get). Before it took about 50 seconds, but now, it takes about 4 seconds.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/180247

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/180247
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=c4945a9bbcd58748d85b845273af6db6a1753f67
Submitter: Jenkins
Branch: master

commit c4945a9bbcd58748d85b845273af6db6a1753f67
Author: Min Song <email address hidden>
Date: Tue May 5 10:02:13 2015 -0700

    Use single connection in get_all function

    As the number of LDAP users increase, any keystone commands that
    need to look through all of the LDAP users tend to slow down.
    After some investigation, I figured out that the cause of this
    is making a new connection for each user in get_all.

    In get_all, it calls _get_enabled function for each LDAP user.
    In _get_enabled function, a new connection from get_connection()
    is created, an then "enabled" value for a user is obtained.
    Therefore, the more LDAP users you have, the slower the response
    will be.

    If a connection is made before the for loop in get_all, get all
    "enabled" values from all users, and then close the connection,
    then the response from keystone commands would be faster.

    This code change was tested on a VM, and it actually speeded up
    many keystone commands (user-list, user-role-add, user-delete,
    user-get) from 50 seconds to 4 seconds.

    Closes-Bug: #1451910
    Change-Id: I3f5131c9eefa066f0d8ee5127322d686e09308df

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/209768
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=dda973ff8cede3a4d4265e0919ad2ab2b0f4c407
Submitter: Jenkins
Branch: master

commit dda973ff8cede3a4d4265e0919ad2ab2b0f4c407
Author: Edgar Magana <email address hidden>
Date: Wed Aug 5 23:16:56 2015 -0700

    Fix explicit line joining with backslash

    In the original fix this bug one reviewed suggested to replace
    backslash but the code was merge before that.

    Change-Id: I1850ccbb63f7bf640adfbb06b0f98567c035067f
    Related-bug: #1451910