├── tests ├── __init__.py ├── requirements.txt ├── settings.py ├── test_utils.py ├── tests.py └── tests_concurrency.py ├── src ├── wallet │ ├── migrations │ │ ├── __init__.py │ │ └── 0001_initial.py │ ├── admin.py │ ├── views.py │ ├── apps.py │ ├── errors.py │ ├── __init__.py │ └── models.py └── LICENCE ├── .gitignore ├── MANIFEST.in ├── setup.cfg ├── runtests.py ├── README.md ├── setup.py └── LICENSE /tests/__init__.py: -------------------------------------------------------------------------------- 1 | -------------------------------------------------------------------------------- /src/wallet/migrations/__init__.py: -------------------------------------------------------------------------------- 1 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | *.pyc 2 | db/ 3 | *.egg-info 4 | *~ 5 | /dist 6 | /build 7 | -------------------------------------------------------------------------------- /MANIFEST.in: -------------------------------------------------------------------------------- 1 | include *.md *.txt LICENSE 2 | recursive-include tests *.py 3 | -------------------------------------------------------------------------------- /setup.cfg: -------------------------------------------------------------------------------- 1 | [bdist_wheel] 2 | universal = 1 3 | 4 | [metadata] 5 | license_file = LICENSE -------------------------------------------------------------------------------- /tests/requirements.txt: -------------------------------------------------------------------------------- 1 | django>=1.11 2 | dj-database-url==0.3.0 3 | mysql-python==1.2.5 4 | -------------------------------------------------------------------------------- /src/wallet/admin.py: -------------------------------------------------------------------------------- 1 | from django.contrib import admin 2 | 3 | # Register your models here. 4 | -------------------------------------------------------------------------------- /src/wallet/views.py: -------------------------------------------------------------------------------- 1 | from django.shortcuts import render 2 | 3 | # Create your views here. 4 | -------------------------------------------------------------------------------- /src/wallet/apps.py: -------------------------------------------------------------------------------- 1 | from django.apps import AppConfig 2 | 3 | 4 | class WalletConfig(AppConfig): 5 | name = 'wallet' 6 | -------------------------------------------------------------------------------- /src/wallet/errors.py: -------------------------------------------------------------------------------- 1 | from django.db import IntegrityError 2 | 3 | 4 | class InsufficientBalance(IntegrityError): 5 | """Raised when a wallet has insufficient balance to 6 | run an operation. 7 | 8 | We're subclassing from :mod:`django.db.IntegrityError` 9 | so that it is automatically rolled-back during django's 10 | transaction lifecycle. 11 | """ 12 | -------------------------------------------------------------------------------- /src/wallet/__init__.py: -------------------------------------------------------------------------------- 1 | __version__ = "0.0.1" 2 | 3 | __title__ = "django-pursed" 4 | __description__ = "A simple wallet django app" 5 | __uri__ = "https://github.com/jpanganiban/django-pursed" 6 | __doc__ = __description__ + " <" + __uri__ + ">" 7 | 8 | __author__ = "Jesse Panganiban" 9 | __email__ = "me@jpanganiban.com" 10 | 11 | __license__ = "GPL" 12 | __copyright__ = "Copyright (c) 2017 Jesse Panganiban" 13 | -------------------------------------------------------------------------------- /tests/settings.py: -------------------------------------------------------------------------------- 1 | import dj_database_url 2 | 3 | DATABASES = { 4 | 'default': dj_database_url.parse('mysql://root:root@mysql/pursed') 5 | } 6 | 7 | 8 | SECRET_KEY = 'fake-key' 9 | 10 | INSTALLED_APPS = ('django.contrib.auth', 11 | 'django.contrib.contenttypes', 12 | 'django.contrib.sessions', 13 | 'django.contrib.admin', 14 | 'django.contrib.sites', 15 | 'wallet', 16 | 'tests', ) 17 | 18 | AUTH_USER_MODEL = 'auth.User' 19 | -------------------------------------------------------------------------------- /runtests.py: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env python 2 | import os 3 | import sys 4 | 5 | import django 6 | 7 | from django.conf import settings 8 | from django.test.utils import get_runner 9 | 10 | 11 | def main(): 12 | os.environ['DJANGO_SETTINGS_MODULE'] = 'tests.settings' 13 | django.setup() 14 | 15 | if sys.argv[0] == 'runtests.py' and len(sys.argv) == 2: 16 | suite = ['' + sys.argv[1]] 17 | else: 18 | suite = ['tests'] 19 | 20 | TestRunner = get_runner(settings) 21 | test_runner = TestRunner() 22 | 23 | failures = test_runner.run_tests(suite, verbosity=1, interactive=True) 24 | 25 | sys.exit(bool(failures)) 26 | 27 | 28 | if __name__ == "__main__": 29 | main() 30 | -------------------------------------------------------------------------------- /tests/test_utils.py: -------------------------------------------------------------------------------- 1 | from django.contrib.auth import get_user_model 2 | from django.test import TransactionTestCase 3 | import logging 4 | 5 | 6 | User = get_user_model() 7 | logger = logging.getLogger(__name__) 8 | 9 | 10 | class WalletTestCase(TransactionTestCase): 11 | 12 | def _create_initial_balance(self, value): 13 | self.wallet.transaction_set.create( 14 | value=value, 15 | running_balance=value 16 | ) 17 | self.wallet.current_balance = value 18 | self.wallet.save() 19 | 20 | def setUp(self): 21 | logger.info('Creating wallet...') 22 | self.user = User() 23 | self.user.save() 24 | self.wallet = self.user.wallet_set.create() 25 | self.wallet.save() 26 | logger.info('Wallet created.') 27 | -------------------------------------------------------------------------------- /src/wallet/migrations/0001_initial.py: -------------------------------------------------------------------------------- 1 | # -*- coding: utf-8 -*- 2 | # Generated by Django 1.9 on 2015-12-09 11:35 3 | from __future__ import unicode_literals 4 | 5 | import datetime 6 | from django.conf import settings 7 | from django.db import migrations, models 8 | import django.db.models.deletion 9 | 10 | 11 | class Migration(migrations.Migration): 12 | 13 | initial = True 14 | 15 | dependencies = [ 16 | migrations.swappable_dependency(settings.AUTH_USER_MODEL), 17 | ] 18 | 19 | operations = [ 20 | migrations.CreateModel( 21 | name='Transaction', 22 | fields=[ 23 | ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')), 24 | ('value', models.BigIntegerField(default=0)), 25 | ('running_balance', models.BigIntegerField(default=0)), 26 | ('created_at', models.DateTimeField(default=datetime.datetime.utcnow)), 27 | ], 28 | ), 29 | migrations.CreateModel( 30 | name='Wallet', 31 | fields=[ 32 | ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')), 33 | ('current_balance', models.BigIntegerField(default=0)), 34 | ('created_at', models.DateTimeField(default=datetime.datetime.utcnow)), 35 | ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)), 36 | ], 37 | ), 38 | migrations.AddField( 39 | model_name='transaction', 40 | name='wallet', 41 | field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='wallet.Wallet'), 42 | ), 43 | ] 44 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | django-pursed 2 | === 3 | 4 | A simple wallet django app. 5 | 6 | ### Creating a New Wallet 7 | 8 | A wallet is owned by a user. Should you be using a custom 9 | user model, the wallet should still work properly as it 10 | the wallet points to `settings.AUTH_USER_MODEL`. 11 | 12 | ```python 13 | from wallet.models import Wallet 14 | 15 | # wallets are owned by users. 16 | wallet = user.wallet_set.create() 17 | ``` 18 | 19 | ### Despositing a balance to a wallet 20 | 21 | ```python 22 | from django.db import transaction 23 | 24 | with transaction.atomic(): 25 | # We need to lock the wallet first so that we're sure 26 | # that nobody modifies the wallet at the same time 27 | # we're modifying it. 28 | wallet = Wallet.select_for_update().get(pk=wallet.id) 29 | wallet.deposit(100) # amount 30 | ``` 31 | 32 | ### Withdrawing a balance from a wallet 33 | 34 | ```python 35 | from django.db import transaction 36 | 37 | with transaction.atomic(): 38 | # We need to lock the wallet first so that we're sure 39 | # that nobody modifies the wallet at the same time 40 | # we're modifying it. 41 | wallet = Wallet.select_for_update().get(pk=wallet.id) 42 | wallet.withdraw(100) # amount 43 | ``` 44 | 45 | ### Withdrawing with an insufficient balance 46 | 47 | When a user tries to withdraw from a wallet with an amount 48 | greater than its balance, the transaction raises a 49 | `wallet.errors.InsufficientBalance` error. 50 | 51 | ```python 52 | # wallet.current_balance # 50 53 | 54 | # This raises an wallet.errors.InsufficentBalance. 55 | wallet.withdraw(100) 56 | ``` 57 | 58 | This error inherits from `django.db.IntegrityError` so that 59 | when it is raised, the whole transaction is automatically 60 | rolled-back. 61 | 62 | ### Transferring between wallets. 63 | 64 | One can transfer a values between wallets. It uses 65 | `withdraw` and `deposit` internally. Should the sending 66 | wallet have an insufficient balance, 67 | `wallet.errors.InsufficientBalance` is raised. 68 | 69 | ```python 70 | with transaction.atomic(): 71 | wallet = Wallet.select_for_update().get(pk=wallet_id) 72 | transfer_to_wallet = Wallet.select_for_update().get(pk=transfer_to_wallet_id) 73 | wallet.transfer(transfer_to_wallet, 100) 74 | ``` 75 | 76 | CURRENCY_STORE_FIELD 77 | --- 78 | 79 | The `CURRENCY_STORE_FIELD` is a django field class that 80 | contains how the fields should be stored. By default, 81 | it uses `django.models.BigIntegerField`. It was chosen that 82 | way for simplicity - just make cents into your smallest 83 | unit (0.01 -> 1, 1.00 -> 100). 84 | 85 | You can change this to decimal by adding this to your 86 | settings.py: 87 | 88 | ```python 89 | # settings.py 90 | CURRENCY_STORE_FIELD = models.DecimalField(max_digits=10, decimal_places=2) 91 | ``` 92 | 93 | You need to run `./manage.py makemigrations` after that. 94 | -------------------------------------------------------------------------------- /setup.py: -------------------------------------------------------------------------------- 1 | import codecs 2 | import os 3 | import re 4 | 5 | from setuptools import setup, find_packages 6 | 7 | 8 | ############################################################################### 9 | 10 | NAME = "django-pursed" 11 | PACKAGES = find_packages(where="src") 12 | META_PATH = os.path.join("src", "wallet", "__init__.py") 13 | KEYWORDS = [""] 14 | CLASSIFIERS = [ 15 | "Development Status :: 4 - Beta", 16 | "Intended Audience :: Developers", 17 | "Natural Language :: English", 18 | "License :: OSI Approved :: MIT License", 19 | "Operating System :: OS Independent", 20 | "Programming Language :: Python", 21 | "Programming Language :: Python :: 2", 22 | "Programming Language :: Python :: 2.7", 23 | "Programming Language :: Python :: 3", 24 | "Programming Language :: Python :: 3.4", 25 | "Programming Language :: Python :: 3.5", 26 | "Topic :: Software Development :: Libraries :: Python Modules", 27 | ] 28 | INSTALL_REQUIRES = [] 29 | 30 | ############################################################################### 31 | 32 | HERE = os.path.abspath(os.path.dirname(__file__)) 33 | 34 | 35 | def read(*parts): 36 | """ 37 | Build an absolute path from *parts* and and return the contents of the 38 | resulting file. Assume UTF-8 encoding. 39 | """ 40 | with codecs.open(os.path.join(HERE, *parts), "rb", "utf-8") as f: 41 | return f.read() 42 | 43 | 44 | META_FILE = read(META_PATH) 45 | 46 | 47 | def find_meta(meta): 48 | """ 49 | Extract __*meta*__ from META_FILE. 50 | """ 51 | meta_match = re.search( 52 | r"^__{meta}__ = ['\"]([^'\"]*)['\"]".format(meta=meta), 53 | META_FILE, re.M 54 | ) 55 | if meta_match: 56 | return meta_match.group(1) 57 | raise RuntimeError("Unable to find __{meta}__ string.".format(meta=meta)) 58 | 59 | 60 | VERSION = find_meta("version") 61 | URI = find_meta("uri") 62 | LONG = ( 63 | # read("README.rst") + "\n\n" # + 64 | read("README.md") + "\n\n" # + 65 | # "Release Information\n" + 66 | # "===================\n\n" + 67 | # re.search("(\d+.\d.\d \(.*?\)\n.*?)\n\n\n----\n\n\n", 68 | # read("CHANGELOG.rst"), re.S).group(1) + 69 | # "\n\n`Full changelog " + 70 | # "<{uri}en/stable/changelog.html>`_.\n\n".format(uri=URI) + 71 | # read("AUTHORS.rst") 72 | ) 73 | 74 | 75 | if __name__ == "__main__": 76 | setup( 77 | name=NAME, 78 | description=find_meta("description"), 79 | license=find_meta("license"), 80 | url=URI, 81 | version=VERSION, 82 | author=find_meta("author"), 83 | author_email=find_meta("email"), 84 | maintainer=find_meta("author"), 85 | maintainer_email=find_meta("email"), 86 | keywords=KEYWORDS, 87 | long_description=LONG, 88 | packages=PACKAGES, 89 | package_dir={"": "src"}, 90 | zip_safe=False, 91 | classifiers=CLASSIFIERS, 92 | install_requires=INSTALL_REQUIRES, 93 | ) 94 | -------------------------------------------------------------------------------- /src/wallet/models.py: -------------------------------------------------------------------------------- 1 | from __future__ import unicode_literals 2 | 3 | from django.conf import settings 4 | from django.db import models 5 | from .errors import InsufficientBalance 6 | 7 | 8 | # We'll be using BigIntegerField by default instead 9 | # of DecimalField for simplicity. This can be configured 10 | # though by setting `WALLET_CURRENCY_STORE_FIELD` in your 11 | # `settings.py`. 12 | CURRENCY_STORE_FIELD = getattr(settings, 13 | 'WALLET_CURRENCY_STORE_FIELD', models.BigIntegerField) 14 | 15 | 16 | class Wallet(models.Model): 17 | # We should reference to the AUTH_USER_MODEL so that 18 | # when this module is used and a different User is used, 19 | # this would still work out of the box. 20 | # 21 | # See 'Referencing the User model' [1] 22 | user = models.ForeignKey(settings.AUTH_USER_MODEL) 23 | 24 | # This stores the wallet's current balance. Also acts 25 | # like a cache to the wallet's balance as well. 26 | current_balance = CURRENCY_STORE_FIELD(default=0) 27 | 28 | # The date/time of the creation of this wallet. 29 | created_at = models.DateTimeField(auto_now_add=True) 30 | 31 | def deposit(self, value): 32 | """Deposits a value to the wallet. 33 | 34 | Also creates a new transaction with the deposit 35 | value. 36 | """ 37 | self.transaction_set.create( 38 | value=value, 39 | running_balance=self.current_balance + value 40 | ) 41 | self.current_balance += value 42 | self.save() 43 | 44 | def withdraw(self, value): 45 | """Withdraw's a value from the wallet. 46 | 47 | Also creates a new transaction with the withdraw 48 | value. 49 | 50 | Should the withdrawn amount is greater than the 51 | balance this wallet currently has, it raises an 52 | :mod:`InsufficientBalance` error. This exception 53 | inherits from :mod:`django.db.IntegrityError`. So 54 | that it automatically rolls-back during a 55 | transaction lifecycle. 56 | """ 57 | if value > self.current_balance: 58 | raise InsufficientBalance('This wallet has insufficient balance.') 59 | 60 | self.transaction_set.create( 61 | value=-value, 62 | running_balance=self.current_balance - value 63 | ) 64 | self.current_balance -= value 65 | self.save() 66 | 67 | def transfer(self, wallet, value): 68 | """Transfers an value to another wallet. 69 | 70 | Uses `deposit` and `withdraw` internally. 71 | """ 72 | self.withdraw(value) 73 | wallet.deposit(value) 74 | 75 | 76 | class Transaction(models.Model): 77 | # The wallet that holds this transaction. 78 | wallet = models.ForeignKey(Wallet) 79 | 80 | # The value of this transaction. 81 | value = CURRENCY_STORE_FIELD(default=0) 82 | 83 | # The value of the wallet at the time of this 84 | # transaction. Useful for displaying transaction 85 | # history. 86 | running_balance = CURRENCY_STORE_FIELD(default=0) 87 | 88 | # The date/time of the creation of this transaction. 89 | created_at = models.DateTimeField(auto_now_add=True) 90 | 91 | 92 | # Footnotes 93 | # [1]: https://docs.djangoproject.com/en/1.9/topics/auth/customizing/#referencing-the-user-model 94 | -------------------------------------------------------------------------------- /tests/tests.py: -------------------------------------------------------------------------------- 1 | from wallet.errors import InsufficientBalance 2 | 3 | from .test_utils import WalletTestCase 4 | 5 | 6 | class BalanceTestCase(WalletTestCase): 7 | 8 | def test_default_balance(self): 9 | self.assertEqual(self.wallet.current_balance, 0) 10 | 11 | 12 | class DepositTestCase(WalletTestCase): 13 | 14 | def test_deposit(self): 15 | """Test the basic wallet deposit operation.""" 16 | DEPOSIT = 100 17 | self.wallet.deposit(DEPOSIT) 18 | 19 | # The wallet's current_balance should also reflect 20 | # the deposit's value. 21 | self.assertEqual(self.wallet.current_balance, DEPOSIT) 22 | 23 | # When I create a deposit, the wallet should create 24 | # a transaction equal to the value of the deposit. 25 | self.assertEqual(self.wallet.transaction_set.first().value, DEPOSIT) 26 | 27 | 28 | class WithdrawTestCase(WalletTestCase): 29 | 30 | def test_withdraw(self): 31 | """Test the basic wallet withdraw operation on a 32 | wallet that has an initial balance.""" 33 | INITIAL_BALANCE = 100 34 | self._create_initial_balance(INITIAL_BALANCE) 35 | 36 | WITHDRAW = 99 37 | self.wallet.withdraw(WITHDRAW) 38 | 39 | # Test that the wallet's current_balance that it 40 | # matches the wallet's initial balance - the 41 | # withdrawn amount. 42 | self.assertEqual(self.wallet.current_balance, 43 | INITIAL_BALANCE - WITHDRAW) 44 | 45 | # When a withdraw transaction succeeds, a 46 | # transaction will be created and it's value should 47 | # match the withdrawn value (as negative). 48 | self.assertEqual(self.wallet.transaction_set.last().value, -WITHDRAW) 49 | 50 | def test_no_balance_withdraw(self): 51 | """Test the basic wallet withdraw operation on a 52 | wallet without any transaction. 53 | """ 54 | with self.assertRaises(InsufficientBalance): 55 | self.wallet.withdraw(100) 56 | 57 | 58 | class TransferTestCase(WalletTestCase): 59 | 60 | def test_transfer(self): 61 | """Test the basic tranfer operation on a wallet.""" 62 | INITIAL_BALANCE = 100 63 | TRANSFER_AMOUNT = 100 64 | self._create_initial_balance(INITIAL_BALANCE) 65 | 66 | # We create a second wallet. 67 | wallet2 = self.user.wallet_set.create() 68 | 69 | # And now, we transfer all the balance the first 70 | # wallet has. 71 | self.wallet.transfer(wallet2, TRANSFER_AMOUNT) 72 | 73 | # We check that the first wallet has its balance 74 | self.assertEqual(self.wallet.current_balance, 75 | INITIAL_BALANCE - TRANSFER_AMOUNT) 76 | 77 | # We also check that the second wallet has the 78 | # transferred balance. 79 | self.assertEqual(wallet2.current_balance, TRANSFER_AMOUNT) 80 | 81 | def test_transfer_insufficient_balance(self): 82 | """Test a scenario where a transfer is done on a 83 | wallet with an insufficient balance.""" 84 | INITIAL_BALANCE = 100 85 | TRANSFER_AMOUNT = 150 86 | self._create_initial_balance(INITIAL_BALANCE) 87 | 88 | # We create a second wallet. 89 | wallet2 = self.user.wallet_set.create() 90 | 91 | with self.assertRaises(InsufficientBalance): 92 | self.wallet.transfer(wallet2, TRANSFER_AMOUNT) 93 | -------------------------------------------------------------------------------- /tests/tests_concurrency.py: -------------------------------------------------------------------------------- 1 | from django.db import transaction 2 | import threading 3 | import time 4 | 5 | from wallet.models import Wallet 6 | from wallet.errors import InsufficientBalance 7 | 8 | from .test_utils import WalletTestCase 9 | 10 | 11 | class ConcurrentDepositTestCase(WalletTestCase): 12 | 13 | def test_deposit(self): 14 | """Test two concurrent deposit transactions.""" 15 | DEPOSIT = 100 16 | 17 | def deposit_thread(sleep=False): 18 | with transaction.atomic(): 19 | wallet = Wallet.objects.select_for_update().get( 20 | pk=self.wallet.id) 21 | wallet.deposit(DEPOSIT) 22 | 23 | # We simulate a long transaction so that 24 | # when the other thread comes in, this 25 | # thread still holds the lock. 26 | if sleep: 27 | time.sleep(0.1) 28 | 29 | # We run the two threads to simulate two 30 | # transactions running simultaneously. 31 | t1 = threading.Thread(target=deposit_thread, args=(True, )) 32 | t2 = threading.Thread(target=deposit_thread) 33 | # t1.start() 34 | t2.start() 35 | t1.run() 36 | t2.join() 37 | 38 | # We retrieve a new wallet object since what we 39 | # currently have is now stale. 40 | wallet = Wallet.objects.get(pk=self.wallet.id) 41 | 42 | # We check that the current_balance wasn't 43 | # overwritten by the other transaction. In short, 44 | # we should get the correct deposited total amount. 45 | self.assertEqual(wallet.current_balance, DEPOSIT * 2) 46 | 47 | # We then check that we have two transactions. Each 48 | # having the deposited amount. 49 | self.assertEqual(wallet.transaction_set.count(), 2) 50 | 51 | def test_withdraw(self): 52 | """Test two concurrent withdraw transactions.""" 53 | INITIAL_BALANCE = 200 54 | self._create_initial_balance(INITIAL_BALANCE) 55 | WITHDRAW = 100 56 | 57 | def withdraw_thread(sleep=False): 58 | with transaction.atomic(): 59 | wallet = Wallet.objects.select_for_update().get( 60 | pk=self.wallet.id) 61 | wallet.withdraw(WITHDRAW) 62 | 63 | # We simulate a long transaction so that 64 | # when the other thread comes in, this 65 | # thread still holds the lock. 66 | if sleep: 67 | time.sleep(0.1) 68 | 69 | t1 = threading.Thread(target=withdraw_thread, args=(True, )) 70 | t2 = threading.Thread(target=withdraw_thread) 71 | # t1.start() 72 | t2.start() 73 | t1.run() 74 | t2.join() 75 | 76 | wallet = Wallet.objects.get(pk=self.wallet.id) 77 | 78 | # Assert that both transactions were able to 79 | # succeed. 80 | self.assertEqual(wallet.current_balance, 81 | INITIAL_BALANCE - (WITHDRAW * 2)) 82 | 83 | # We also check that the number of transactions 84 | # created only equates to the number of 85 | # transactions successful + the initial transaction. 86 | self.assertEqual(wallet.transaction_set.count(), 3) 87 | 88 | def test_multiple_withdraw_insufficient_balance(self): 89 | """We're going to test two concurrent withdraw 90 | transactions happening in parallel where one would 91 | end-up with an insufficient balance.""" 92 | INITIAL_BALANCE = 199 93 | self._create_initial_balance(INITIAL_BALANCE) 94 | WITHDRAW = 100 95 | 96 | def withdraw_thread(sleep=False): 97 | with transaction.atomic(): 98 | wallet = Wallet.objects.select_for_update().get( 99 | pk=self.wallet.id) 100 | try: 101 | wallet.withdraw(WITHDRAW) 102 | except InsufficientBalance: 103 | pass 104 | 105 | # We simulate a long transaction so that 106 | # when the other thread comes in, this 107 | # thread still holds the lock. 108 | if sleep: 109 | time.sleep(0.1) 110 | 111 | t1 = threading.Thread(target=withdraw_thread, args=(True, )) 112 | t2 = threading.Thread(target=withdraw_thread) 113 | # t1.start() 114 | t2.start() 115 | t1.run() 116 | t2.join() 117 | 118 | wallet = Wallet.objects.get(pk=self.wallet.id) 119 | 120 | # Assert that the only the first transaction was 121 | # able to succeed by checking that only one 122 | # transaction's value was applied. 123 | self.assertEqual(wallet.current_balance, 124 | INITIAL_BALANCE - (WITHDRAW * 1)) 125 | 126 | # We also check that the number of transactions 127 | # created only equates to the number of 128 | # transactions successful + the initial transaction. 129 | self.assertEqual(wallet.transaction_set.count(), 2) 130 | 131 | 132 | class ConcurrentTransferTestCase(WalletTestCase): 133 | 134 | def test_transfer(self): 135 | """We're going to simulate concurrent transfer to a 136 | single wallet.""" 137 | INITIAL_BALANCE = 200 138 | self._create_initial_balance(INITIAL_BALANCE) 139 | TRANSFER = 100 140 | 141 | _wallet2 = self.user.wallet_set.create() 142 | wallet2_id = _wallet2.id 143 | 144 | def transfer_thread(sleep=False): 145 | with transaction.atomic(): 146 | wallet = Wallet.objects.select_for_update().get( 147 | pk=self.wallet.id) 148 | wallet2 = Wallet.objects.select_for_update().get(pk=wallet2_id) 149 | wallet.transfer(wallet2, TRANSFER) 150 | 151 | # We simulate a long transaction so that 152 | # when the other thread comes in, this 153 | # thread still holds the lock. 154 | if sleep: 155 | time.sleep(0.1) 156 | 157 | t1 = threading.Thread(target=transfer_thread, args=(True, )) 158 | t2 = threading.Thread(target=transfer_thread) 159 | # t1.start() 160 | t2.start() 161 | t1.run() 162 | t2.join() 163 | 164 | wallet = Wallet.objects.get(pk=self.wallet.id) 165 | wallet2 = Wallet.objects.get(pk=wallet2_id) 166 | 167 | # Assert that all transfers were made and that 168 | # both applies to the wallet's current_balance. 169 | self.assertEqual(wallet.current_balance, 170 | INITIAL_BALANCE - (TRANSFER * 2)) 171 | self.assertEqual(wallet2.current_balance, TRANSFER * 2) 172 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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No Surrender of Others' Freedom. 541 | 542 | If conditions are imposed on you (whether by court order, agreement or 543 | otherwise) that contradict the conditions of this License, they do not 544 | excuse you from the conditions of this License. If you cannot convey a 545 | covered work so as to satisfy simultaneously your obligations under this 546 | License and any other pertinent obligations, then as a consequence you may 547 | not convey it at all. For example, if you agree to terms that obligate you 548 | to collect a royalty for further conveying from those to whom you convey 549 | the Program, the only way you could satisfy both those terms and this 550 | License would be to refrain entirely from conveying the Program. 551 | 552 | 13. Use with the GNU Affero General Public License. 553 | 554 | Notwithstanding any other provision of this License, you have 555 | permission to link or combine any covered work with a work licensed 556 | under version 3 of the GNU Affero General Public License into a single 557 | combined work, and to convey the resulting work. The terms of this 558 | License will continue to apply to the part which is the covered work, 559 | but the special requirements of the GNU Affero General Public License, 560 | section 13, concerning interaction through a network will apply to the 561 | combination as such. 562 | 563 | 14. Revised Versions of this License. 564 | 565 | The Free Software Foundation may publish revised and/or new versions of 566 | the GNU General Public License from time to time. Such new versions will 567 | be similar in spirit to the present version, but may differ in detail to 568 | address new problems or concerns. 569 | 570 | Each version is given a distinguishing version number. If the 571 | Program specifies that a certain numbered version of the GNU General 572 | Public License "or any later version" applies to it, you have the 573 | option of following the terms and conditions either of that numbered 574 | version or of any later version published by the Free Software 575 | Foundation. If the Program does not specify a version number of the 576 | GNU General Public License, you may choose any version ever published 577 | by the Free Software Foundation. 578 | 579 | If the Program specifies that a proxy can decide which future 580 | versions of the GNU General Public License can be used, that proxy's 581 | public statement of acceptance of a version permanently authorizes you 582 | to choose that version for the Program. 583 | 584 | Later license versions may give you additional or different 585 | permissions. However, no additional obligations are imposed on any 586 | author or copyright holder as a result of your choosing to follow a 587 | later version. 588 | 589 | 15. Disclaimer of Warranty. 590 | 591 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 592 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 596 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 597 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 599 | 600 | 16. Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. 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Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | --------------------------------------------------------------------------------