Prioritize Freezer Scheduler Jobs

We need to have a priority system for executing Freezer Scheduler jobs.

If you added job to freezer it will be registered with normal priority which can default to 0

If you have more important job you can assign a priority greater than zero as big as you want.

Freezer Scheduler must make sure that the jobs with less priority will be executed at a point of time.

Example:

1) Extremely important

+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| job_id | description | # actions | status | event | result | session_id | priority |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 1 | job1 | backup | ---- | | Success | a2dxxc345s2 | -1 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+

2) Jobs

+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| job_id | description | # actions | status | event | result | session_id | priority |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 1 | job1 | backup | ---- | | Success | a2dxuc345s2 | 0 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 2 | job2 | backup | ---- | | Success | a2dxnc345s2 | 5 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 3 | job3 | restore | ---- | | Success | a2dsxc345s2 | 9 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 4 | job4 | backup | ---- | | Success | qdnsxc345s2 | 0 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 5 | job5 | restore | ---- | | Success | zpdxxc345s2 | 3 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+
| 6 | job6 | backup | ---- | | Success | oodxic345s2 | 0 |
+---------+-------------------+---------------+-----------+----------+--------------+---------------------+------------------+

These jobs will be executed in the following order:

1. Job 3
2. Job 2
3. Job 5
4. Job 1
5. Job 4
6. Job 6

Jobs with priority '0' doesn't matter the execution order.
I think this will allow the users to add multiple jobs and will be a nice to organize and manage jobs by the freezer user.