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Merge pull request #599 from liberapay/payday-temporal-symmetry
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Implement temporal symmetry for donations to teams
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@Changaco
Changaco authored Jun 2, 2017
2 parents 03ec64a + ac2b967 commit 0b146eb
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286 changes: 174 additions & 112 deletions liberapay/billing/payday.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,9 @@
# coding: utf8

from __future__ import print_function, unicode_literals

from datetime import date
from decimal import Decimal, ROUND_UP
import os
import os.path
import pickle
Expand All @@ -19,6 +22,10 @@
log = print


def round_up(d):
return d.quantize(constants.D_CENT, rounding=ROUND_UP)


class NoPayday(Exception):
__str__ = lambda self: "No payday found where one was expected."

Expand Down Expand Up @@ -67,7 +74,7 @@ def start(cls):
payday.__dict__.update(d)
return payday

def run(self, log_dir='.', keep_log=False):
def run(self, log_dir='.', keep_log=False, recompute_stats=10, update_cached_amounts=True):
"""This is the starting point for payday.
It is structured such that it can be run again safely (with a
Expand All @@ -83,8 +90,9 @@ def run(self, log_dir='.', keep_log=False):

self.end()

self.recompute_stats(limit=10)
self.update_cached_amounts()
self.recompute_stats(limit=recompute_stats)
if update_cached_amounts:
self.update_cached_amounts()

self.notify_participants()

Expand Down Expand Up @@ -115,7 +123,7 @@ def shuffle(self, log_dir='.'):
else:
with self.db.get_cursor() as cursor:
self.prepare(cursor, self.ts_start)
self.transfer_virtually(cursor)
self.transfer_virtually(cursor, self.ts_start)
transfers = [NS(t._asdict()) for t in cursor.all("""
SELECT t.*
, p.mangopay_user_id AS tipper_mango_id
Expand Down Expand Up @@ -282,119 +290,175 @@ def prepare(cursor, ts_start):
END;
$$ LANGUAGE plpgsql;
-- Create a function to resolve many-to-many donations (team takes)
CREATE OR REPLACE FUNCTION resolve_takes(team_id bigint) RETURNS void AS $$
DECLARE
total_income numeric(35,2);
total_takes numeric(35,2);
takes_ratio numeric;
tips_ratio numeric;
tip record;
take record;
transfer_amount numeric(35,2);
our_tips CURSOR FOR
SELECT t.id, t.tipper, (round_up(t.amount * tips_ratio, 2)) AS amount
FROM payday_tips t
JOIN payday_participants p ON p.id = t.tipper
WHERE t.tippee = team_id
AND p.new_balance >= t.amount;
BEGIN
WITH funded AS (
UPDATE payday_tips
SET is_funded = true
FROM payday_participants p
WHERE p.id = tipper
AND tippee = team_id
AND p.new_balance >= amount
RETURNING amount
)
SELECT COALESCE(sum(amount), 0) FROM funded INTO total_income;
total_takes := (
SELECT COALESCE(sum(t.amount), 0)
FROM payday_takes t
WHERE t.team = team_id
);
IF (total_income = 0 OR total_takes = 0) THEN RETURN; END IF;
takes_ratio := min(total_income / total_takes, 1::numeric);
tips_ratio := min(total_takes / total_income, 1::numeric);
DROP TABLE IF EXISTS our_takes;
CREATE TEMPORARY TABLE our_takes ON COMMIT DROP AS
SELECT t.member, (round_up(t.amount * takes_ratio, 2)) AS amount
FROM payday_takes t
WHERE t.team = team_id;
FOR tip IN our_tips LOOP
FOR take IN (SELECT * FROM our_takes ORDER BY member) LOOP
IF (take.amount = 0 OR tip.tipper = take.member) THEN
CONTINUE;
END IF;
transfer_amount := min(tip.amount, take.amount);
EXECUTE transfer(tip.tipper, take.member, transfer_amount, 'take', team_id, NULL);
tip.amount := tip.amount - transfer_amount;
UPDATE our_takes t
SET amount = take.amount - transfer_amount
WHERE t.member = take.member;
EXIT WHEN tip.amount = 0;
END LOOP;
END LOOP;
RETURN;
END;
$$ LANGUAGE plpgsql;
-- Create a function to pay invoices
CREATE OR REPLACE FUNCTION pay_invoices() RETURNS void AS $$
DECLARE
invoices_cursor CURSOR FOR
SELECT i.*
FROM invoices i
WHERE i.status = 'accepted'
AND ( SELECT ie.ts
FROM invoice_events ie
WHERE ie.invoice = i.id
ORDER BY ts DESC
LIMIT 1
) < %(ts_start)s;
payer_balance numeric(35,2);
BEGIN
FOR i IN invoices_cursor LOOP
payer_balance := (
SELECT p.new_balance
FROM payday_participants p
WHERE id = i.addressee
);
IF (payer_balance < i.amount) THEN
CONTINUE;
END IF;
EXECUTE transfer(i.addressee, i.sender, i.amount,
i.nature::text::transfer_context,
NULL, i.id);
UPDATE invoices
SET status = 'paid'
WHERE id = i.id;
INSERT INTO invoice_events
(invoice, participant, status)
VALUES (i.id, i.addressee, 'paid');
END LOOP;
END;
$$ LANGUAGE plpgsql;
""", dict(ts_start=ts_start))
log("Prepared the DB.")

@staticmethod
def transfer_virtually(cursor):
def transfer_virtually(cursor, ts_start):
cursor.run("SELECT settle_tip_graph();")
teams = cursor.all("""
SELECT id FROM payday_participants WHERE kind = 'group';
""")
for team_id in teams:
Payday.resolve_takes(cursor, team_id)
cursor.run("""
SELECT settle_tip_graph();
SELECT resolve_takes(id) FROM payday_participants WHERE kind = 'group';
SELECT settle_tip_graph();
UPDATE payday_tips SET is_funded = false WHERE is_funded IS NULL;
SELECT pay_invoices();
""")
Payday.pay_invoices(cursor, ts_start)

@staticmethod
def resolve_takes(cursor, team_id):
"""Resolve many-to-many donations (team takes)
"""
args = dict(team_id=team_id)
total_income = cursor.one("""
WITH funded AS (
UPDATE payday_tips
SET is_funded = true
FROM payday_participants p
WHERE p.id = tipper
AND tippee = %(team_id)s
AND p.new_balance >= amount
RETURNING amount
)
SELECT COALESCE(sum(amount), 0) FROM funded;
""", args)
total_takes = cursor.one("""
SELECT COALESCE(sum(t.amount), 0)
FROM payday_takes t
WHERE t.team = %(team_id)s
""", args)
if total_income == 0 or total_takes == 0:
return
args['takes_ratio'] = min(total_income / total_takes, 1)
tips_ratio = args['tips_ratio'] = min(total_takes / total_income, 1)
tips = [NS(t._asdict()) for t in cursor.all("""
SELECT t.id, t.tipper, (round_up(t.amount * %(tips_ratio)s, 2)) AS amount
, t.amount AS full_amount
, COALESCE((
SELECT sum(tr.amount)
FROM transfers tr
WHERE tr.tipper = t.tipper
AND tr.team = %(team_id)s
AND tr.context = 'take'
AND tr.status = 'succeeded'
), 0) AS past_transfers_sum
FROM payday_tips t
JOIN payday_participants p ON p.id = t.tipper
WHERE t.tippee = %(team_id)s
AND p.new_balance >= t.amount
""", args)]
takes = [NS(t._asdict()) for t in cursor.all("""
SELECT t.member, (round_up(t.amount * %(takes_ratio)s, 2)) AS amount
FROM payday_takes t
WHERE t.team = %(team_id)s;
""", args)]
adjust_tips = tips_ratio != 1
if adjust_tips:
# The team has a leftover, so donation amounts can be adjusted.
# In the following loop we compute the "weeks" count of each tip.
# For example the `weeks` value is 2.5 for a donation currently at
# 10€/week which has distributed 25€ in the past.
for tip in tips:
tip.weeks = round_up(tip.past_transfers_sum / tip.full_amount)
max_weeks = max(tip.weeks for tip in tips)
min_weeks = min(tip.weeks for tip in tips)
adjust_tips = max_weeks != min_weeks
if adjust_tips:
# Some donors have given fewer weeks worth of money than others,
# we want to adjust the amounts so that the weeks count will
# eventually be the same for every donation.
min_tip_ratio = tips_ratio * Decimal('0.1')
# Loop: compute how many "weeks" each tip is behind the "oldest"
# tip, as well as a naive ratio and amount based on that number
# of weeks
for tip in tips:
tip.weeks_to_catch_up = max_weeks - tip.weeks
tip.ratio = min(min_tip_ratio + tip.weeks_to_catch_up, 1)
tip.amount = round_up(tip.full_amount * tip.ratio)
naive_amounts_sum = sum(tip.amount for tip in tips)
total_to_transfer = min(total_takes, total_income)
delta = total_to_transfer - naive_amounts_sum
if delta == 0:
# The sum of the naive amounts computed in the previous loop
# matches the end target, we got very lucky and no further
# adjustments are required
adjust_tips = False
else:
# Loop: compute the "leeway" of each tip, i.e. how much it
# can be increased or decreased to fill the `delta` gap
if delta < 0:
# The naive amounts are too high: we want to lower the
# amounts of the tips that have a "high" ratio, leaving
# untouched the ones that are already low
for tip in tips:
if tip.ratio > min_tip_ratio:
min_tip_amount = round_up(tip.full_amount * min_tip_ratio)
tip.leeway = min_tip_amount - tip.amount
else:
tip.leeway = 0
else:
# The naive amounts are too low: we can raise all the
# tips that aren't already at their maximum
for tip in tips:
tip.leeway = tip.full_amount - tip.amount
leeway = sum(tip.leeway for tip in tips)
leeway_ratio = min(delta / leeway, 1)
tips = sorted(tips, key=lambda tip: (-tip.weeks_to_catch_up, tip.id))
# Loop: compute the adjusted donation amounts, and do the transfers
for tip in tips:
if adjust_tips:
tip_amount = round_up(tip.amount + tip.leeway * leeway_ratio)
if tip_amount == 0:
continue
assert tip_amount > 0
assert tip_amount <= tip.full_amount
tip.amount = tip_amount
for take in takes:
if take.amount == 0 or tip.tipper == take.member:
continue
transfer_amount = min(tip.amount, take.amount)
cursor.run("SELECT transfer(%s, %s, %s, 'take', %s, NULL)",
(tip.tipper, take.member, transfer_amount, team_id))
tip.amount -= transfer_amount
take.amount -= transfer_amount
if tip.amount == 0:
break

@staticmethod
def pay_invoices(cursor, ts_start):
"""Settle pending invoices
"""
invoices = cursor.all("""
SELECT i.*
FROM invoices i
WHERE i.status = 'accepted'
AND ( SELECT ie.ts
FROM invoice_events ie
WHERE ie.invoice = i.id
ORDER BY ts DESC
LIMIT 1
) < %(ts_start)s;
""", dict(ts_start=ts_start))
for i in invoices:
payer_balance = cursor.one("""
SELECT p.new_balance
FROM payday_participants p
WHERE id = %s
""", (i.addressee,))
if payer_balance < i.amount:
continue
cursor.run("""
SELECT transfer(%(addressee)s, %(sender)s, %(amount)s,
%(nature)s::transfer_context, NULL, %(id)s);
UPDATE invoices
SET status = 'paid'
WHERE id = %(id)s;
INSERT INTO invoice_events
(invoice, participant, status)
VALUES (%(id)s, %(addressee)s, 'paid');
""", i._asdict())

@staticmethod
def check_balances(cursor):
Expand Down Expand Up @@ -432,8 +496,6 @@ def clean_up(self):
DROP FUNCTION process_tip();
DROP FUNCTION settle_tip_graph();
DROP FUNCTION transfer(bigint, bigint, numeric, transfer_context, bigint, int);
DROP FUNCTION resolve_takes(bigint);
DROP FUNCTION pay_invoices();
""")

@classmethod
Expand Down Expand Up @@ -563,7 +625,7 @@ def update_cached_amounts(self):
now = pando.utils.utcnow()
with self.db.get_cursor() as cursor:
self.prepare(cursor, now)
self.transfer_virtually(cursor)
self.transfer_virtually(cursor, now)
cursor.run("""
UPDATE tips t
Expand Down
2 changes: 1 addition & 1 deletion tests/py/test_charts_json.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@ def setUp(self):
self.bob.set_tip_to(self.carl, '2.00')

def run_payday(self):
Payday.start().run()
Payday.start().run(recompute_stats=1)


def test_no_payday_returns_empty_list(self):
Expand Down
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