Files
relay/chatmaild/src/chatmaild/database.py
2023-10-15 16:07:26 +00:00

141 lines
4.2 KiB
Python

import sqlite3
import contextlib
import time
from pathlib import Path
class DBError(Exception):
"""error during an operation on the database."""
class Connection:
def __init__(self, sqlconn, write):
self._sqlconn = sqlconn
self._write = write
def close(self):
self._sqlconn.close()
def commit(self):
self._sqlconn.commit()
def rollback(self):
self._sqlconn.rollback()
def execute(self, query, params=()):
cur = self.cursor()
try:
cur.execute(query, params)
except sqlite3.IntegrityError as e:
raise DBError(e)
return cur
def cursor(self):
return self._sqlconn.cursor()
def create_user(self, addr: str, password: str):
"""Create a row in the users table."""
self.execute("PRAGMA foreign_keys=on")
q = """INSERT INTO users (addr, password, last_login)
VALUES (?, ?, ?)"""
self.execute(q, (addr, password, int(time.time())))
def get_user(self, addr: str) -> {}:
"""Get a row from the users table."""
q = "SELECT addr, password, last_login from users WHERE addr = ?"
row = self._sqlconn.execute(q, (addr,)).fetchone()
result = {}
if row:
result = dict(
user=row[0],
password=row[1],
last_login=row[2],
)
return result
class Database:
def __init__(self, path: str):
self.path = Path(path)
self.ensure_tables()
def _get_connection(
self, write=False, transaction=False, closing=False
) -> Connection:
# we let the database serialize all writers at connection time
# to play it very safe (we don't have massive amounts of writes).
mode = "ro"
if write:
mode = "rw"
if not self.path.exists():
mode = "rwc"
uri = "file:%s?mode=%s" % (self.path, mode)
sqlconn = sqlite3.connect(
uri,
timeout=60,
isolation_level=None if transaction else "DEFERRED",
uri=True,
)
# Enable Write-Ahead Logging to avoid readers blocking writers and vice versa.
if write:
sqlconn.execute("PRAGMA journal_mode=wal")
if transaction:
start_time = time.time()
while 1:
try:
sqlconn.execute("begin immediate")
break
except sqlite3.OperationalError:
# another thread may be writing, give it a chance to finish
time.sleep(0.1)
if time.time() - start_time > 5:
# if it takes this long, something is wrong
raise
conn = Connection(sqlconn, write=write)
if closing:
conn = contextlib.closing(conn)
return conn
@contextlib.contextmanager
def write_transaction(self):
conn = self._get_connection(closing=False, write=True, transaction=True)
try:
yield conn
except Exception:
conn.rollback()
conn.close()
raise
else:
conn.commit()
conn.close()
def read_connection(self, closing=True) -> Connection:
return self._get_connection(closing=closing, write=False)
def get_schema_version(self) -> int:
with self.read_connection() as conn:
dbversion = conn.execute("PRAGMA user_version").fetchone()[0]
return dbversion
CURRENT_DBVERSION = 1
def ensure_tables(self):
with self.write_transaction() as conn:
if self.get_schema_version() > 1:
raise DBError(
"version is %s; downgrading schema is not supported"
% (self.get_schema_version(),)
)
conn.execute(
"""
CREATE TABLE IF NOT EXISTS users (
addr TEXT PRIMARY KEY,
password TEXT,
last_login INTEGER
)
""",
)
conn.execute("PRAGMA user_version=%s" % (self.CURRENT_DBVERSION,))