dynamo_sessions.py 文件源码

def lookup(account_id=None, user_id=None, session_id=None, max_expired_age=None):
    q = {'Select': 'ALL_ATTRIBUTES'}
    if user_id is not None:
        q['KeyConditionExpression'] = Key('userId').eq(user_id)
        if session_id is not None:
            q['KeyConditionExpression'] = q['KeyConditionExpression'] & Key('sessionId').eq(session_id)
        if account_id is not None:
            q['FilterExpression'] = Attr('accountId').eq(account_id)
    elif account_id is not None:
        # use the account GSI
        q['KeyConditionExpression'] = Key('accountId').eq(account_id)
        q['IndexName'] = os.getenv('SESSION_TABLE_ACCOUNT_GSI')
        if session_id is not None:
            q['FilterExpression'] = Attr('sessionId').eq(session_id)
    elif session_id is not None:
        q['FilterExpression'] = Attr('sessionId').eq(session_id)
    else:
        return get_all_sessions(max_expired_age=max_expired_age)

    if max_expired_age is not None:
        exp_filter = Attr('expires').gte(int(time.time()-max_expired_age))
        if 'FilterExpression' in q:
            q['FilterExpression'] = q['FilterExpression'] & exp_filter
        else:
            q['FilterExpression'] = exp_filter

    if 'KeyConditionExpression' in q:
        return collect_results(get_session_table().query,q)
    else:
        return collect_results(get_session_table().scan,q)

# expensive call, so cache briefly if we have a flood of broadcast messages