Current bucket state model

The bucket state model at October 2017

The purpose of these changes was to make it clear how much money was needed to be available in the group. To do that it was necessary to add information about whether the money contributed to a bucket was paid out or not.

The changes was done in way that did not require changes to all bucket records in the database.

These are the states a bucket can be in:

• Idea - New bucket. Only used for discussion at this point. The target is not fixed yet.
  • status == 'draft'
  • archived_at not set.
  • It can transition to Funding or Cancelled.
  • No contributions should exist.
• Funding - People can start contributing to the bucket. The bucket is not yet fully funded and not cancelled.
  • status == 'live'
  • archived_at not set.
  • It can transition to Funded or Cancelled.
  • Contributions can exist.
  • target is now fixed and can’t be changed.
  • If a contribution is added that makes the sum of contribution go over target, it will be adjusted down. Thus no buckets should have contributions that are over target. This is an invariant.
  • If a contribution is added that makes the sum of contributions equal to target the status get set to funded
• Funded - The bucket is fully funded. It’s not completed and it's not cancelled.
  • status == 'funded'
  • paid_at not set.
  • It can transition to Completed or Cancelled.
  • Contributions can exist.
  • archived_at can be set or not. If archived_at is set, it means the bucket was Archived in the old state model.
• Completed - The bucket is funded and the money has been paid. It's less visible on the group page.
  • status == 'funded'
  • paid_at is set.
  • There's no transition out of this state.
  • Contributions can exist.
  • archived_at can be set or not. If archived_at is set, it means the bucket was Archived in the old state model.
• Cancelled - The bucket is cancelled. It’s not possible to contribute to it. Any previous contributions has been deleted. It’s less visible on the group page.
  • archived_at is set.
  • paid_at is not set.
  • (status == 'draft') || (status == 'live') || (status == 'refunded')
  • There's no transition out of this state.
  • No contributions should exist.

The change from the old state model to the new state model

Old state	New state	Comments
Idea	Idea
Funding	Funding
Funded	Funded	paid_at is null at creation, so it stays in the same state
Archived	Funded	We're just ignoring archived_at since we know it's not cancelled
Cancelled	Cancelled	paid_at is null. Old Archived buckets that get's cancelled set status = 'refunded'

A simple way of determining state

We create a bit vector. The elements are status, if archived_at is set and if paid_at is set.

We set the values of status to:

status	Decimal value	Binary value
draft	0	00
live	1	01
funded	2	10
refunded	3	11

For archived_at and paid_at we define a value of 1 if it's set and 0 if it's not set.

We define the bit-vector: <status 2 bits><archived_at 1 bit><paid_at 1 bit>. 4 bits in total giving it values between 0 and 15.

The states then become:

Decimal vector value	Binary vector value	State	Comment
0	0000	Idea
1	0001	Illegal	paid_at shouldn't be set if status == 'draft'
2	0010	Cancelled
3	0011	Illegal	paid_at shouldn't be set if status == 'draft'
4	0100	Funding
5	0101	Illegal	´paid_atshouldn't be set whenstatus == 'live'`
6	0110	Cancelled
7	0111	Illegal	´paid_atshouldn't be set whenstatus == 'live'`
8	1000	Funded	Ignoring archived_at
9	1001	Completed	Ignoring archived_at
10	1010	Funded	Ignoring archived_at
11	1011	Completed	Ignoring archived_at
12	1100	Illegal	archived_at should be set when status == 'refunded'
13	1101	Illegal	paid_at should not be set when status == 'refunded'
14	1110	Cancelled
15	1111	Illegal	paid_at should not be set when status == 'refunded'