Replace six.text_type with str.
A subsequent patch will replace other six.text_type.

Change-Id: I23bb9e539d08f5c6202909054c2dd49b6c7a7a0e
Implements: blueprint six-removal
Signed-off-by: Takashi Natsume <takanattie@gmail.com>

We have a race where if a user issues a delete request while an
instance is in the middle of booting, we could fail to update the
'queued_for_delete' field on the instance mapping with:

  sqlalchemy.orm.exc.StaleDataError: UPDATE statement on table
  'instance_mappings' expected to update 1 row(s); 0 were matched.

This happens if we've retrieved the instance mapping record from the
database and then it gets deleted by nova-conductor before we attempt
to save() it.

This handles the situation by adding try-except around the update call
to catch StaleDataError and raise InstanceMappingNotFound instead,
which the caller does know how to handle.

Closes-Bug: #1882608

Change-Id: I2cdcad7226312ed81f4242c8d9ac919715524b48

Change-Id: I6381365ff882cf23808e8dabfce41143c5e35192
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

This addresses comments from the series:

  * Remove usage-specific info from docstring
  * Add note to nova-next job description "changelog"
  * Add info about data migration to config option help
  * Consolidate code under count_usage_from_placement conditional
  * Consolidate variables for checking data migration doneness
  * Remove hard-coded user_id and project_id from func test
  * Re-word code comment about checking data migration doneness

Related to blueprint count-quota-usage-from-placement

Change-Id: Ida2de9256fcc9e092fb9977b8ac067fc1472c316

This adds a get_count_by_uuids_and_user() method to the InstanceMapping
object and uses it to count instance mappings for the purpose of
counting quota usage for server group members. By counting server group
members via instance mappings, the count is resilient to down cells in
a multi-cell environment.

Part of blueprint count-quota-usage-from-placement

Change-Id: I3ff39d5ed99a68ad8678e5ff62b343f3018b4768

This counts instance mappings for the purpopse of counting quota
usage for instances. By counting instances via instance mappings, the
count is resilient to down cells in a multi-cell environment.

Part of blueprint count-quota-usage-from-placement

Change-Id: I7c1ae466a6a6b6d82548396e0c94b1cdab600b5c

This adds an online data migration for the user_id field on
InstanceMapping. It does this by processing instance mappings that do
not have a value set for the field (i.e. are NULL in the database) and
queries instances in each cell that need to be updated.

Part of blueprint count-quota-usage-from-placement

Change-Id: I8cc873ba63db7b806ab1de0a88fe8a87d4baeea9

This adds the new user_id column from the instance_mappings table as
a field in the InstanceMapping object. There is already a project_id
field containing the project_id for the instance. The user_id field
will contain the corresponding user_id for the instance.

Part of blueprint count-quota-usage-from-placement

Change-Id: I0f523b2a2e09e1ece9e1911325e55cffd183a9d5

The data migration was needlessly querying the cell database
for instances even if there were no instance mappings in that
database that needed to be migrated. This simply continues to
the next cell if the instance mappings in the current cell are
migrated.

While we're in here, the joinedload on 'cell_mapping' can be
removed since it's not used.

Closes-Bug: #1817961

Change-Id: Idf35ed9d57945bc80fbd47393b7de076330160e6

1) Change it to accommodate querying it for 'None' project_ids
   in the "--all-tenats" case.
2) If the online data migration for populating queued_for_delete
   has not been run for some reason, the the values could be NULL
   in the database for instance_mapping.queued_for_delete. Under
   such circumstances, we assume that such mappings with NULL
   queued_for_delete have *not* being queued_for_deletion.

Related to blueprint handling-down-cell

Change-Id: I80a65bc026e26a272a9dc041b27f9839511db765