Mini Shell

# -*- coding: utf-8 -*-

# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2021 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
import logging
import os
import threading
from contextlib import contextmanager
from dataclasses import dataclass
from typing import Dict, Generator

from xray.internal.constants import request_data_storage

logger = logging.getLogger(__name__)


@dataclass
class TaskCounterStorage:
    """
    Typing that has lock and value storage with some syntax sugar.
    """
    lock: threading.Lock
    next_request_id: int

    @property
    def processed_requests(self):
        return self.next_request_id - 1


_request_id_storage: Dict[str, TaskCounterStorage] = dict()
_global_storage_lock = threading.Lock()


@contextmanager
def open_local_storage(fake_task_id: str, flush=False) -> Generator[TaskCounterStorage, None, None]:
    """
    Open local task information storage.
    @param fake_task_id:
        unique string, usually obtained as task.fake_id
    @param flush:
        whether to save data to file right after update
    """
    logger.debug('Opening storage %s', fake_task_id)
    storage = _get_or_create_record(fake_task_id)
    with storage.lock:
        yield storage

        if flush:
            logger.info('Updating task %s requests counter in file', fake_task_id)
            _save_data_to_file(fake_task_id, storage)


def remove_local_storage(fake_task_id):
    """
    Remove local storage record.
    @param fake_task_id:
        unique string, usually obtained as task.fake_id
    """
    logger.info('Removing memory storage for task %s', fake_task_id)
    with _global_storage_lock:
        if fake_task_id in _request_id_storage:
            del _request_id_storage[fake_task_id]


def get_task_ids():
    """
    List all fake task ids saved in local storage.
    """
    return list(_request_id_storage)


def flush_memory_storage(remove=True):
    """
    List all fake task ids saved in local storage.
    """
    for fake_task_id in list(_request_id_storage.keys()):
        logger.info('Flushing task id %s on disk', fake_task_id)
        with open_local_storage(fake_task_id) as storage:
            _save_data_to_file(fake_task_id, storage)
            if remove:
                del _request_id_storage[fake_task_id]


def _save_data_to_file(fake_task_id: str, storage: TaskCounterStorage):
    """
    Saves storage data from memory to file.
    """
    req_id_file = os.path.join(request_data_storage, fake_task_id)
    with open(req_id_file, 'w') as f:
        f.write(str(storage.next_request_id))


def _get_or_create_record(fake_task_id) -> TaskCounterStorage:
    """
    Takes record from local storage or creates new one and returns object
    """
    with _global_storage_lock:
        if fake_task_id not in _request_id_storage:
            _request_id_storage[fake_task_id] = TaskCounterStorage(
                lock=threading.Lock(),
                next_request_id=1
            )

            storage = _request_id_storage[fake_task_id]

            req_id_file = os.path.join(request_data_storage, fake_task_id)
            try:
                with open(req_id_file, 'r') as f:
                    storage.next_request_id = int(f.read())
            except FileNotFoundError:
                pass
        else:
            storage = _request_id_storage[fake_task_id]
    return storage