Mercurial

annotate asyncio_threads/bank_question/main.py @ 210:0abed117e623

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Updated manifest color.
author MrJuneJune <me@mrjunejune.com>
date Sun, 15 Feb 2026 15:47:38 -0800
parents 46daba6e3cf4
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
48
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
1 # # Bank Account
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
2 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
3 # You are given a simplified multi-threaded “bank account” implementation used by one of our infrastructure teams. The current code processes deposits concurrently but produces incorrect results.
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
4 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
5 # Task
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
6 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
7 # Identify the concurrency bugs in the implementation.
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
8 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
9 # Explain why these bugs occur.
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
10 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
11 # Fix the implementation without modifying the existing BankAccount class directly.
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
12 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
13 # You may use subclassing (Python) or embedding (Go-style composition), depending on the language you choose.
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
14 #
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
15 # Ensure your solution is thread-safe and produces the correct final balance (1200).
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
16
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
17 from threading import Lock
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
18 from concurrent.futures import ThreadPoolExecutor
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
19 import time
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
20
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
21 class BankAccount:
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
22 def __init__(self, balance):
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
23 self.balance = balance
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
24 self._lock = Lock()
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
25
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
26 def deposit(self, amount):
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
27 while (self._lock.locked()):
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
28 pass
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
29 self._lock.acquire()
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
30 new_balance = self.balance + amount # read
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
31 time.sleep(0.1) # simulate delay
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
32 self.balance = new_balance # write
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
33 self._lock.release()
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
34
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
35
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
36 account = BankAccount(0)
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
37
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
38 with ThreadPoolExecutor(max_workers=2) as executor:
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
39 futures = [
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
40 executor.submit(account.deposit, 500),
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
41 executor.submit(account.deposit, 700),
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
42 ]
46daba6e3cf4 Few python scrtips to show how to use asychio.
MrJuneJune <me@mrjunejune.com>
parents:
diff changeset
43 print(account.balance)