DescribeSecurityGroups very slow in EC2 API

[MotoKen]

DescribeSecurityGroups is very slow in EC2 API if user makes strong use of grantee group rules.
This is the case especially for admin to describe all tenants' groups.

Versions:
master, stable/folsom, stable/essex, stable/diablo

To reproduce:
1. set quota security_groups to 100
2. run the following script:

#!/bin/bash
for i in $(seq 1 99)
do
    euca-add-group group-$i -d group-$i
    for j in $(seq 1 20)
    do
        euca-authorize group-$i -P tcp -p $j -o default
    done
done

3. time euca-describe-groups
real 0m42.857s
user 0m0.240s
sys 0m0.030s

[Michael Still (mikal)]

What openstack version are you running?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/15187

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/15187
Committed: http://github.com/openstack/nova/commit/358ccf5f196b6b43f18778afae279633c051c6d9
Submitter: Jenkins
Branch: master

commit 358ccf5f196b6b43f18778afae279633c051c6d9
Author: MotoKen <email address hidden>
Date: Thu Nov 1 15:07:52 2012 +0800

    Improve EC2 describe_security_groups performance

    The current implementation of EC2 describe_security_groups makes one
    query per grantee group rule in _format_security_group. This will
    dramatically slow down response time if users make strong use of
    grantee group rules.

    This patch uses just one DB query to get security groups with joined
    grantee_group rules to improve the performance.

    Fixes bug 1073024.

    Change-Id: I34f3253bfef0eabfea39819de03a274dd6f6aaa8