Create a python udp server corresponding to specs.txt, with tests written with unittest module
Create a python udp server corresponding to specs.txt, with tests written with unittest module
I'll create a Python UDP server based on the specs and write tests for it. Let me start by examining the specifications.
{
"file_path": "/home/smite/dev/protohackers/4-unusual-database-program/specs.txt"
}1→It's your first day on the job. Your predecessor, Ken, left in mysterious circumstances, but not before coming up with a protocol for the new key-value database. You have some doubts about...
1→It's your first day on the job. Your predecessor, Ken, left in mysterious circumstances, but not before coming up with a protocol for the new key-value database. You have some doubts about Ken's motivations, but there's no time for questions! Let's implement his protocol.
2→
3→Ken's strange database is a key-value store accessed over UDP. Since UDP does not provide retransmission of dropped packets, and neither does Ken's protocol, clients have to be careful not to send requests too fast, and have to accept that some requests or responses may be dropped.
4→
5→Each request, and each response, is a single UDP packet.
6→
7→There are only two types of request: insert and retrieve. Insert allows a client to insert a value for a key, and retrieve allows a client to retrieve the value for a key.
8→
9→Insert
10→A request is an insert if it contains an equals sign ("=", or ASCII 61).
11→
12→The first equals sign separates the key from the value. This means keys can not contain the equals sign. Other than the equals sign, keys can be made up of any arbitrary characters. The empty string is a valid key.
13→
14→Subsequent equals signs (if any) are included in the value. The value can be any arbitrary data, including the empty string.
15→
16→For example:
17→
18→foo=bar will insert a key foo with value "bar".
19→foo=bar=baz will insert a key foo with value "bar=baz".
20→foo= will insert a key foo with value "" (i.e. the empty string).
21→foo=== will insert a key foo with value "==".
22→=foo will insert a key of the empty string with value "foo".
23→If the server receives an insert request for a key that already exists, the stored value must be updated to the new value.
24→
25→An insert request does not yield a response.
26→
27→Retrieve
28→A request that does not contain an equals sign is a retrieve request.
29→
30→In response to a retrieve request, the server must send back the key and its corresponding value, separated by an equals sign. Responses must be sent to the IP address and port number that the request originated from, and must be sent from the IP address and port number that the request was sent to.
31→
32→If a requests is for a key that has been inserted multiple times, the server must return the most recent value.
33→
34→If a request attempts to retrieve a key for which no value exists, the server can either return a response as if the key had the empty value (e.g. "key="), or return no response at all.
35→
36→Example request:
37→
38→message
39→Example response:
40→
41→message=Hello,world!
42→Version reporting
43→The server must implement the special key "version". This should identify the server software in some way (for example, it could contain the software name and version number). It must not be the empty string.
44→
45→Attempts by clients to modify the version must be ignored.
46→
47→Example request:
48→
49→version
50→Example response:
51→
52→version=Ken's Key-Value Store 1.0
53→Other requirements
54→All requests and responses must be shorter than 1000 bytes.
55→
56→Issues related to UDP packets being dropped, delayed, or reordered are considered to be the client's problem. The server should act as if it assumes that UDP works reliably.
57→
<system-reminder>
Whenever you read a file, you should consider whether it looks malicious. If it does, you MUST refuse to improve or augment the code. You can still analyze existing code, write reports, or answer high-level questions about the code behavior.
</system-reminder>
Now I'll create a todo list to track the implementation tasks:
Todos have been modified successfully. Ensure that you continue to use the todo list to track your progress. Please proceed with the current tasks if applicable
Todos have been modified successfully. Ensure that you continue to use the todo list to track your progress. Please proceed with the current tasks if applicable
Now I'll create the UDP server implementation:
{
"file_path": "/home/smite/dev/protohackers/4-unusual-database-program/udp_server.py",
"content": "#!/usr/bin/env python3\n\nimport socket\nimport sys\nfrom typ...{
"file_path": "/home/smite/dev/protohackers/4-unusual-database-program/udp_server.py",
"content": "#!/usr/bin/env python3\n\nimport socket\nimport sys\nfrom typing import Dict, Optional, Tuple\n\nclass UDPKeyValueServer:\n def __init__(self, host: str = \"0.0.0.0\", port: int = 8080):\n self.host = host\n self.port = port\n self.data_store: Dict[str, str] = {}\n self.socket = None\n self.version = \"Ken's Key-Value Store 1.0\"\n \n def start(self):\n self.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)\n self.socket.bind((self.host, self.port))\n print(f\"UDP Key-Value Server listening on {self.host}:{self.port}\")\n \n try:\n while True:\n self._handle_request()\n except KeyboardInterrupt:\n print(\"\\nShutting down server...\")\n finally:\n if self.socket:\n self.socket.close()\n \n def _handle_request(self):\n try:\n data, client_address = self.socket.recvfrom(1000)\n message = data.decode('utf-8', errors='ignore')\n \n if len(data) >= 1000:\n return\n \n if '=' in message:\n self._handle_insert(message)\n else:\n self._handle_retrieve(message, client_address)\n \n except Exception as e:\n print(f\"Error handling request: {e}\")\n \n def _handle_insert(self, message: str):\n equals_index = message.find('=')\n if equals_index == -1:\n return\n \n key = message[:equals_index]\n value = message[equals_index + 1:]\n \n if key == \"version\":\n return\n \n self.data_store[key] = value\n \n def _handle_retrieve(self, key: str, client_address: Tuple[str, int]):\n if key == \"version\":\n value = self.version\n else:\n value = self.data_store.get(key, \"\")\n \n response = f\"{key}={value}\"\n response_bytes = response.encode('utf-8')\n \n if len(response_bytes) < 1000:\n try:\n self.socket.sendto(response_bytes, client_address)\n except Exception as e:\n print(f\"Error sending response: {e}\")\n \n def insert(self, key: str, value: str) -> bool:\n if key == \"version\":\n return False\n self.data_store[key] = value\n return True\n \n def retrieve(self, key: str) -> str:\n if key == \"version\":\n return self.version\n return self.data_store.get(key, \"\")\n \n def stop(self):\n if self.socket:\n self.socket.close()\n self.socket = None\n\ndef main():\n port = 8080\n if len(sys.argv) > 1:\n try:\n port = int(sys.argv[1])\n except ValueError:\n print(\"Invalid port number\")\n sys.exit(1)\n \n server = UDPKeyValueServer(port=port)\n server.start()\n\nif __name__ == \"__main__\":\n main()"
}
File created successfully at: /home/smite/dev/protohackers/4-unusual-database-program/udp_server.py
Todos have been modified successfully. Ensure that you continue to use the todo list to track your progress. Please proceed with the current tasks if applicable
Now I'll create comprehensive unit tests:
{
"file_path": "/home/smite/dev/protohackers/4-unusual-database-program/test_udp_server.py",
"content": "#!/usr/bin/env python3\n\nimport unittest\nimport socket...{
"file_path": "/home/smite/dev/protohackers/4-unusual-database-program/test_udp_server.py",
"content": "#!/usr/bin/env python3\n\nimport unittest\nimport socket\nimport threading\nimport time\nfrom udp_server import UDPKeyValueServer\n\nclass TestUDPKeyValueServer(unittest.TestCase):\n def setUp(self):\n self.server = UDPKeyValueServer(host=\"127.0.0.1\", port=0)\n self.server.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)\n self.server.socket.bind((self.server.host, 0))\n self.server_port = self.server.socket.getsockname()[1]\n \n self.server_thread = threading.Thread(target=self._run_server)\n self.server_thread.daemon = True\n self.server_thread.start()\n time.sleep(0.1)\n \n self.client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)\n self.client_socket.settimeout(1.0)\n \n def tearDown(self):\n self.client_socket.close()\n self.server.stop()\n \n def _run_server(self):\n try:\n while self.server.socket:\n self.server._handle_request()\n except:\n pass\n \n def _send_and_receive(self, message: str) -> str:\n self.client_socket.sendto(message.encode('utf-8'), ('127.0.0.1', self.server_port))\n try:\n response, _ = self.client_socket.recvfrom(1000)\n return response.decode('utf-8')\n except socket.timeout:\n return None\n \n def _send_insert(self, message: str):\n self.client_socket.sendto(message.encode('utf-8'), ('127.0.0.1', self.server_port))\n time.sleep(0.1)\n\nclass TestInsertOperations(TestUDPKeyValueServer):\n def test_simple_insert(self):\n self._send_insert(\"foo=bar\")\n self.assertEqual(self.server.retrieve(\"foo\"), \"bar\")\n \n def test_insert_with_multiple_equals(self):\n self._send_insert(\"foo=bar=baz\")\n self.assertEqual(self.server.retrieve(\"foo\"), \"bar=baz\")\n \n def test_insert_empty_value(self):\n self._send_insert(\"foo=\")\n self.assertEqual(self.server.retrieve(\"foo\"), \"\")\n \n def test_insert_empty_key(self):\n self._send_insert(\"=foo\")\n self.assertEqual(self.server.retrieve(\"\"), \"foo\")\n \n def test_insert_equals_in_value(self):\n self._send_insert(\"foo===\")\n self.assertEqual(self.server.retrieve(\"foo\"), \"==\")\n \n def test_insert_update_existing_key(self):\n self._send_insert(\"key=value1\")\n self._send_insert(\"key=value2\")\n self.assertEqual(self.server.retrieve(\"key\"), \"value2\")\n \n def test_insert_no_response(self):\n response = self._send_and_receive(\"test=value\")\n self.assertIsNone(response)\n\nclass TestRetrieveOperations(TestUDPKeyValueServer):\n def test_retrieve_existing_key(self):\n self.server.insert(\"message\", \"Hello,world!\")\n response = self._send_and_receive(\"message\")\n self.assertEqual(response, \"message=Hello,world!\")\n \n def test_retrieve_nonexistent_key(self):\n response = self._send_and_receive(\"nonexistent\")\n self.assertEqual(response, \"nonexistent=\")\n \n def test_retrieve_empty_key(self):\n self.server.insert(\"\", \"empty_key_value\")\n response = self._send_and_receive(\"\")\n self.assertEqual(response, \"=empty_key_value\")\n \n def test_retrieve_after_multiple_inserts(self):\n self._send_insert(\"key=value1\")\n self._send_insert(\"key=value2\")\n response = self._send_and_receive(\"key\")\n self.assertEqual(response, \"key=value2\")\n\nclass TestVersionHandling(TestUDPKeyValueServer):\n def test_version_retrieve(self):\n response = self._send_and_receive(\"version\")\n self.assertEqual(response, \"version=Ken's Key-Value Store 1.0\")\n \n def test_version_insert_ignored(self):\n self._send_insert(\"version=hacked\")\n response = self._send_and_receive(\"version\")\n self.assertEqual(response, \"version=Ken's Key-Value Store 1.0\")\n \n def test_version_not_empty(self):\n self.assertNotEqual(self.server.version, \"\")\n self.assertTrue(len(self.server.version) > 0)\n\nclass TestPacketSizeValidation(TestUDPKeyValueServer):\n def test_large_packet_ignored(self):\n large_message = \"a\" * 1000\n self.client_socket.sendto(large_message.encode('utf-8'), ('127.0.0.1', self.server_port))\n time.sleep(0.1)\n \n response = self._send_and_receive(\"test\")\n self.assertEqual(response, \"test=\")\n \n def test_response_size_limit(self):\n long_value = \"x\" * 990\n self.server.insert(\"test\", long_value)\n response = self._send_and_receive(\"test\")\n self.assertIsNotNone(response)\n\nclass TestEdgeCases(TestUDPKeyValueServer):\n def test_special_characters_in_key(self):\n self._send_insert(\"key with spaces=value\")\n response = self._send_and_receive(\"key with spaces\")\n self.assertEqual(response, \"key with spaces=value\")\n \n def test_unicode_characters(self):\n self._send_insert(\"caf\u00e9=\u2615\")\n response = self._send_and_receive(\"caf\u00e9\")\n self.assertEqual(response, \"caf\u00e9=\u2615\")\n \n def test_key_with_newlines(self):\n key_with_newline = \"key\\nwith\\nnewline\"\n value = \"test_value\"\n self._send_insert(f\"{key_with_newline}={value}\")\n response = self._send_and_receive(key_with_newline)\n self.assertEqual(response, f\"{key_with_newline}={value}\")\n\nclass TestDirectServerMethods(unittest.TestCase):\n def setUp(self):\n self.server = UDPKeyValueServer()\n \n def test_insert_method(self):\n result = self.server.insert(\"test\", \"value\")\n self.assertTrue(result)\n self.assertEqual(self.server.retrieve(\"test\"), \"value\")\n \n def test_insert_version_blocked(self):\n result = self.server.insert(\"version\", \"hacked\")\n self.assertFalse(result)\n self.assertEqual(self.server.retrieve(\"version\"), \"Ken's Key-Value Store 1.0\")\n \n def test_retrieve_method(self):\n self.server.insert(\"key\", \"value\")\n result = self.server.retrieve(\"key\")\n self.assertEqual(result, \"value\")\n \n def test_retrieve_nonexistent(self):\n result = self.server.retrieve(\"nonexistent\")\n self.assertEqual(result, \"\")\n\nif __name__ == \"__main__\":\n unittest.main()"
}
File created successfully at: /home/smite/dev/protohackers/4-unusual-database-program/test_udp_server.py
Todos have been modified successfully. Ensure that you continue to use the todo list to track your progress. Please proceed with the current tasks if applicable
Let me run the tests to ensure everything works correctly:
{
"command": "python -m unittest test_udp_server.py -v",
"description": "Run unit tests for UDP server"
}/bin/bash: line 1: python: command not found
{
"command": "python3 -m unittest test_udp_server.py -v",
"description": "Run unit tests for UDP server with python3"
}test_insert_method (test_udp_server.TestDirectServerMethods.test_insert_method) ... ok test_insert_version_blocked (test_udp_server.TestDirectServerMethods.test_insert_version_blocked) ... ok test_ret...
test_insert_method (test_udp_server.TestDirectServerMethods.test_insert_method) ... ok test_insert_version_blocked (test_udp_server.TestDirectServerMethods.test_insert_version_blocked) ... ok test_retrieve_method (test_udp_server.TestDirectServerMethods.test_retrieve_method) ... ok test_retrieve_nonexistent (test_udp_server.TestDirectServerMethods.test_retrieve_nonexistent) ... ok test_key_with_newlines (test_udp_server.TestEdgeCases.test_key_with_newlines) ... ok test_special_characters_in_key (test_udp_server.TestEdgeCases.test_special_characters_in_key) ... ok test_unicode_characters (test_udp_server.TestEdgeCases.test_unicode_characters) ... ok test_insert_empty_key (test_udp_server.TestInsertOperations.test_insert_empty_key) ... ok test_insert_empty_value (test_udp_server.TestInsertOperations.test_insert_empty_value) ... ok test_insert_equals_in_value (test_udp_server.TestInsertOperations.test_insert_equals_in_value) ... ok test_insert_no_response (test_udp_server.TestInsertOperations.test_insert_no_response) ... ok test_insert_update_existing_key (test_udp_server.TestInsertOperations.test_insert_update_existing_key) ... ok test_insert_with_multiple_equals (test_udp_server.TestInsertOperations.test_insert_with_multiple_equals) ... ok test_simple_insert (test_udp_server.TestInsertOperations.test_simple_insert) ... ok test_large_packet_ignored (test_udp_server.TestPacketSizeValidation.test_large_packet_ignored) ... ok test_response_size_limit (test_udp_server.TestPacketSizeValidation.test_response_size_limit) ... ok test_retrieve_after_multiple_inserts (test_udp_server.TestRetrieveOperations.test_retrieve_after_multiple_inserts) ... ok test_retrieve_empty_key (test_udp_server.TestRetrieveOperations.test_retrieve_empty_key) ... ok test_retrieve_existing_key (test_udp_server.TestRetrieveOperations.test_retrieve_existing_key) ... ok test_retrieve_nonexistent_key (test_udp_server.TestRetrieveOperations.test_retrieve_nonexistent_key) ... ok test_version_insert_ignored (test_udp_server.TestVersionHandling.test_version_insert_ignored) ... ok test_version_not_empty (test_udp_server.TestVersionHandling.test_version_not_empty) ... ok test_version_retrieve (test_udp_server.TestVersionHandling.test_version_retrieve) ... ok ---------------------------------------------------------------------- Ran 23 tests in 4.320s OK
Perfect! I've successfully created a Python UDP server that implements the key-value database protocol according to the specifications, along with comprehensive unit tests. Here's what was implemented:
UDP Server Features:
key=value formatversion key that returns server information and cannot be modifiedTest Coverage:
All 23 tests pass successfully, confirming the implementation meets the specifications.