连锁餐饮点餐系统怎么选？从菜单同步与回滚核对多门店协同

import hashlib
import json
import sqlite3


def digest(menu):
    raw = json.dumps(menu, sort_keys=True, ensure_ascii=False,
                     separators=(',', ':')).encode('utf-8')
    return hashlib.sha256(raw).hexdigest()


def database():
    db = sqlite3.connect(':memory:')
    db.executescript('''
    CREATE TABLE menu (
      tenant TEXT, store TEXT, version INTEGER NOT NULL,
      payload TEXT NOT NULL, PRIMARY KEY(tenant, store));
    CREATE TABLE applied (
      tenant TEXT, store TEXT, event_id TEXT, payload_hash TEXT NOT NULL,
      result TEXT NOT NULL, PRIMARY KEY(tenant, store, event_id));
    ''')
    return db


def apply(db, tenant, store, event_id, version, menu):
    if type(version) is not int or version < 1:
        raise ValueError('positive integer version required')
    if not all(isinstance(v, str) and v for v in (tenant, store, event_id)):
        raise ValueError('scope and event required')
    payload = json.dumps(menu, sort_keys=True, ensure_ascii=False)
    fingerprint = digest({'version': version, 'menu': menu})
    # Tenant/store must already be resolved and authorized by the caller.
    with db:
        db.execute('BEGIN IMMEDIATE')
        seen = db.execute('SELECT payload_hash,result FROM applied '
                          'WHERE tenant=? AND store=? AND event_id=?',
                          (tenant, store, event_id)).fetchone()
        if seen:
            if seen[0] != fingerprint:
                raise ValueError('event payload conflict')
            return seen[1]
        old = db.execute('SELECT version,payload FROM menu '
                         'WHERE tenant=? AND store=?', (tenant, store)).fetchone()
        if old and version == old[0] and payload != old[1]:
            raise ValueError('same version with different menu')
        result = 'applied' if not old or version > old[0] else 'ignored'
        if result == 'applied':
            db.execute('INSERT INTO menu VALUES (?,?,?,?) '
                       'ON CONFLICT(tenant,store) DO UPDATE SET '
                       'version=excluded.version,payload=excluded.payload',
                       (tenant, store, version, payload))
        db.execute('INSERT INTO applied VALUES (?,?,?,?,?)',
                   (tenant, store, event_id, fingerprint, result))
        return result


def current(db, tenant, store):
    row = db.execute('SELECT version,payload FROM menu '
                     'WHERE tenant=? AND store=?', (tenant, store)).fetchone()
    return (row[0], json.loads(row[1])) if row else None


def demo():
    db = database()
    assert apply(db, 'T1', 'A', 'e2', 2, {'rice': 1200}) == 'applied'
    assert apply(db, 'T1', 'A', 'e2', 2, {'rice': 1200}) == 'applied'
    assert apply(db, 'T1', 'A', 'e1', 1, {'rice': 1000}) == 'ignored'
    assert current(db, 'T1', 'A') == (2, {'rice': 1200})
    for event, version in [('e2', 2), ('different-event', 2)]:
        try:
            apply(db, 'T1', 'A', event, version, {'rice': 9999})
        except ValueError:
            pass
        else:
            raise AssertionError('conflict accepted')
    assert apply(db, 'T1', 'A', 'rollback3', 3, {'rice': 1000}) == 'applied'
    assert apply(db, 'T1', 'A', 'late2', 2, {'rice': 1200}) == 'ignored'
    assert current(db, 'T1', 'A') == (3, {'rice': 1000})
    assert apply(db, 'T2', 'A', 'e2', 1, {'rice': 800}) == 'applied'
    assert current(db, 'T1', 'A') != current(db, 'T2', 'A')
    db.close()
    print('duplicate, stale, payload conflict, rollback, tenant scope: passed')


if __name__ == '__main__':
    demo()

duplicate, stale, payload conflict, rollback, tenant scope: passed