示例#1
0
class FileSystemSessionInterface(SessionInterface):
    """Uses the :class:`werkzeug.contrib.cache.FileSystemCache` as a session
    backend.

    :param cache_dir: the directory where session files are stored.
    :param threshold: the maximum number of items the session stores before it
                      starts deleting some.
    :param mode: the file mode wanted for the session files, default 0600
    :param key_prefix: A prefix that is added to FileSystemCache store keys.
    """

    session_class = FileSystemSession

    def __init__(self, cache_dir, threshold, mode, key_prefix):
        from werkzeug.contrib.cache import FileSystemCache
        self.cache = FileSystemCache(cache_dir, threshold=threshold, mode=mode)
        self.key_prefix = key_prefix

    def _generate_sid(self):
        return str(uuid4())

    def open_session(self, app, request):
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            sid = self._generate_sid()
            return self.session_class(sid=sid)
        data = self.cache.get(self.key_prefix + sid)
        if data is not None:
            return self.session_class(data, sid=sid)
        return self.session_class(sid=sid)
    
    def save_session(self, app, session, response):
        domain = self.get_cookie_domain(app)
        path = self.get_cookie_path(app)
        if not session:
            if session.modified:
                self.cache.delete(self.key_prefix + session.sid)
                response.delete_cookie(app.session_cookie_name,
                                       domain=domain, path=path)
            return

        # Modification case.  There are upsides and downsides to
        # emitting a set-cookie header each request.  The behavior
        # is controlled by the :meth:`should_set_cookie` method
        # which performs a quick check to figure out if the cookie
        # should be set or not.  This is controlled by the
        # SESSION_REFRESH_EACH_REQUEST config flag as well as
        # the permanent flag on the session itself.
        # if not self.should_set_cookie(app, session):
        #    return

        httponly = self.get_cookie_httponly(app)
        secure = self.get_cookie_secure(app)
        expires = self.get_expiration_time(app, session)
        data = dict(session)
        self.cache.set(self.key_prefix + session.sid, data,
                         int(app.permanent_session_lifetime.total_seconds()))
        response.set_cookie(app.session_cookie_name, session.sid,
                            expires=expires, httponly=httponly,
                            domain=domain, path=path, secure=secure)
示例#2
0
class FileSystemSessionInterface(SessionInterface):
    """Uses the :class:`werkzeug.contrib.cache.FileSystemCache` as a session
    backend.

    :param cache_dir: the directory where session files are stored.
    :param threshold: the maximum number of items the session stores before it
                      starts deleting some.
    :param mode: the file mode wanted for the session files, default 0600
    :param key_prefix: A prefix that is added to FileSystemCache store keys.
    """

    session_class = FileSystemSession

    def __init__(self, cache_dir, threshold, mode, key_prefix):
        from werkzeug.contrib.cache import FileSystemCache
        self.cache = FileSystemCache(cache_dir, threshold=threshold, mode=mode)
        self.key_prefix = key_prefix

    def _generate_sid(self):
        return str(uuid4())

    def open_session(self, app, request):
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            sid = self._generate_sid()
            return self.session_class(sid=sid)
        data = self.cache.get(self.key_prefix + sid)
        if data is not None:
            return self.session_class(data, sid=sid)
        return self.session_class(sid=sid)
    
    def save_session(self, app, session, response):
        domain = self.get_cookie_domain(app)
        path = self.get_cookie_path(app)
        if not session:
            if session.modified:
                self.cache.delete(self.key_prefix + session.sid)
                response.delete_cookie(app.session_cookie_name,
                                       domain=domain, path=path)
            return

        # Modification case.  There are upsides and downsides to
        # emitting a set-cookie header each request.  The behavior
        # is controlled by the :meth:`should_set_cookie` method
        # which performs a quick check to figure out if the cookie
        # should be set or not.  This is controlled by the
        # SESSION_REFRESH_EACH_REQUEST config flag as well as
        # the permanent flag on the session itself.
        #if not self.should_set_cookie(app, session):
        #    return

        httponly = self.get_cookie_httponly(app)
        secure = self.get_cookie_secure(app)
        expires = self.get_expiration_time(app, session)
        data = dict(session)
        self.cache.set(self.key_prefix + session.sid, data,
                         int(app.permanent_session_lifetime.total_seconds()))
        response.set_cookie(app.session_cookie_name, session.sid,
                            expires=expires, httponly=httponly,
                            domain=domain, path=path, secure=secure)
示例#3
0
class WechatCache(WechatSogouBase):
    """基于文件的缓存

    """
    def __init__(self, cache_dir='cache', default_timeout=300):
        """初始化

        cache_dir是缓存目录
        """
        self.cache = FileSystemCache(cache_dir,
                                     default_timeout=default_timeout)

    def clear(self):
        """清空缓存
        """
        return self.cache.clear()

    def get(self, key):
        """获取缓存

        获取键值key的缓存值
        如果没有对应缓存,返回None
        """
        return self.cache.get(key)

    def add(self, key, value, timeout=None):
        """增加缓存

        如果键值key对应的缓存不存在,那么增加值value到键值key,过期时间timeout,默认300秒
        否则返回False(即不能覆盖设置缓存)
        """
        return self.cache.add(key, value, timeout)

    def set(self, key, value, timeout=None):
        """设置缓存

        设置键值key的缓存为value,过期时间300秒
        """
        return self.cache.set(key, value, timeout)

    def delete(self, key):
        """删除缓存

        删除键值key存储的缓存
        """
        return self.cache.delete(key)
示例#4
0
class WechatCache(object):
    """基于文件的缓存

    """

    def __init__(self, cache_dir='cache', default_timeout=300):
        """初始化

        cache_dir是缓存目录
        """
        self.cache = FileSystemCache(cache_dir, default_timeout=default_timeout)

    def clear(self):
        """清空缓存
        """
        return self.cache.clear()

    def get(self, key):
        """获取缓存

        获取键值key的缓存值
        如果没有对应缓存,返回None
        """
        return self.cache.get(key)

    def add(self, key, value, timeout=None):
        """增加缓存

        如果键值key对应的缓存不存在,那么增加值value到键值key,过期时间timeout,默认300秒
        否则返回False(即不能覆盖设置缓存)
        """
        return self.cache.add(key, value, timeout)

    def set(self, key, value, timeout=None):
        """设置缓存

        设置键值key的缓存为value,过期时间300秒
        """
        return self.cache.set(key, value, timeout)

    def delete(self, key):
        """删除缓存

        删除键值key存储的缓存
        """
        return self.cache.delete(key)
示例#5
0
class WechatCache:
    def __init__(self, cache_dir='cache', default_timeout=300):

        self.cache = FileSystemCache(cache_dir=cache_dir,
                                     default_timeout=default_timeout)

    def clear(self):
        return self.cache.clear()

    def get(self, key):
        return self.cache.get(key)

    def add(self, key, value, timeout=None):
        return self.cache.add(key, value, timeout)

    def set(self, key, value, timeout=None):
        return self.cache.set(key, value, timeout)

    def delete(self, key):
        return self.cache.delete(key)
示例#6
0
class FileSystemSessionInterface(SessionInterface):
    """Uses the :class:`werkzeug.contrib.cache.FileSystemCache` as a session
    backend.

    .. versionadded:: 0.2
        The `use_signer` parameter was added.

    :param cache_dir: the directory where session files are stored.
    :param threshold: the maximum number of items the session stores before it
                      starts deleting some.
    :param mode: the file mode wanted for the session files, default 0600
    :param key_prefix: A prefix that is added to FileSystemCache store keys.
    :param use_signer: Whether to sign the session id cookie or not.
    :param permanent: Whether to use permanent session or not.
    """

    session_class = FileSystemSession

    def __init__(self,
                 cache_dir,
                 threshold,
                 mode,
                 key_prefix,
                 use_signer=False,
                 permanent=True):
        from werkzeug.contrib.cache import FileSystemCache
        self.cache = FileSystemCache(cache_dir, threshold=threshold, mode=mode)
        self.key_prefix = key_prefix
        self.use_signer = use_signer
        self.permanent = permanent

    def open_session(self, app, request):
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            sid = self._generate_sid()
            return self.session_class(sid=sid, permanent=self.permanent)
        if self.use_signer:
            signer = self._get_signer(app)
            if signer is None:
                return None
            try:
                sid_as_bytes = signer.unsign(sid)
                sid = sid_as_bytes.decode()
            except BadSignature:
                sid = self._generate_sid()
                return self.session_class(sid=sid, permanent=self.permanent)

        data = self.cache.get(self.key_prefix + sid)
        if data is not None:
            return self.session_class(data, sid=sid)
        return self.session_class(sid=sid, permanent=self.permanent)

    def save_session(self, app, session, response):
        domain = self.get_cookie_domain(app)
        path = self.get_cookie_path(app)
        if not session:
            if session.modified:
                self.cache.delete(self.key_prefix + session.sid)
                response.delete_cookie(app.session_cookie_name,
                                       domain=domain,
                                       path=path)
            return

        httponly = self.get_cookie_httponly(app)
        secure = self.get_cookie_secure(app)
        expires = self.get_expiration_time(app, session)
        samesite = self.get_cookie_samesite(app)
        data = dict(session)
        self.cache.set(self.key_prefix + session.sid, data,
                       total_seconds(app.permanent_session_lifetime))
        if self.use_signer:
            session_id = self._get_signer(app).sign(want_bytes(session.sid))
        else:
            session_id = session.sid
        response.set_cookie(app.session_cookie_name,
                            session_id,
                            expires=expires,
                            httponly=httponly,
                            domain=domain,
                            path=path,
                            secure=secure,
                            samesite=samesite)
示例#7
0
class FileSystemSessionInterface(SessionInterface):
    """Uses the :class:`werkzeug.contrib.cache.FileSystemCache` as a session
    backend.

    .. versionadded:: 0.2
        The `use_signer` parameter was added.

    :param cache_dir: the directory where session files are stored.
    :param threshold: the maximum number of items the session stores before it
                      starts deleting some.
    :param mode: the file mode wanted for the session files, default 0600
    :param key_prefix: A prefix that is added to FileSystemCache store keys.
    :param use_signer: Whether to sign the session id cookie or not.
    :param permanent: Whether to use permanent session or not.
    """

    session_class = FileSystemSession

    def __init__(self, cache_dir, threshold, mode, key_prefix,
                 use_signer=False, permanent=True):
        from werkzeug.contrib.cache import FileSystemCache
        self.cache = FileSystemCache(cache_dir, threshold=threshold, mode=mode)
        self.key_prefix = key_prefix
        self.use_signer = use_signer
        self.permanent = permanent

    def open_session(self, app, request):
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            sid = self._generate_sid()
            return self.session_class(sid=sid, permanent=self.permanent)
        if self.use_signer:
            signer = self._get_signer(app)
            if signer is None:
                return None
            try:
                sid = signer.unsign(sid)
            except BadSignature:
                sid = self._generate_sid()
                return self.session_class(sid=sid, permanent=self.permanent)

        data = self.cache.get(self.key_prefix + sid)
        if data is not None:
            return self.session_class(data, sid=sid)
        return self.session_class(sid=sid, permanent=self.permanent)

    def save_session(self, app, session, response):
        domain = self.get_cookie_domain(app)
        path = self.get_cookie_path(app)
        if not session:
            if session.modified:
                self.cache.delete(self.key_prefix + session.sid)
                response.delete_cookie(app.session_cookie_name,
                                       domain=domain, path=path)
            return

        httponly = self.get_cookie_httponly(app)
        secure = self.get_cookie_secure(app)
        expires = self.get_expiration_time(app, session)
        data = dict(session)
        self.cache.set(self.key_prefix + session.sid, data,
                       total_seconds(app.permanent_session_lifetime))
        if self.use_signer:
            session_id = self._get_signer(app).sign(session.sid)
        else:
            session_id = session.sid
        response.set_cookie(app.session_cookie_name, session_id,
                            expires=expires, httponly=httponly,
                            domain=domain, path=path, secure=secure)
示例#8
0
class Cache(object):
    """Cache module based on werkzeug.contrib.cache. This is a mixed
    version of NullCache, SimpleCache, FileSystemCache, MemcachedCache,
    and RedisCache.

    :param app: Flask app instance.
    :param config_prefix: Define a prefix for Flask app config.
    :param kwargs: Extra parameters.

    You need to configure a type of the cache, and its related configurations.
    The default ``config_prefix`` is ``AUTHLIB``, so it requires a config of::

        AUTHLIB_CACHE_TYPE = 'simple'

    If ``config_prefix`` is something else, like ``EXAMPLE``, it would be::

        EXAMPLE_CACHE_TYPE = 'simple'

    The available cache types are:

    * null: It will not cache anything. No configuration.

    * simple: It caches things in memory.
      The only configuration is ``threshold``::

          AUTHLIB_CACHE_THRESHOLD = 500

    * memcache: It caches things in Memcache. Available configurations::

          AUTHLIB_CACHE_MEMCACHED_SERVERS = []
          AUTHLIB_CACHE_KEY_PREFIX = None

    * redis: It caches things in Redis. Available configurations::

          AUTHLIB_CACHE_REDIS_HOST = 'localhost'
          AUTHLIB_CACHE_REDIS_PORT = 6379
          AUTHLIB_CACHE_REDIS_PASSWORD = None
          AUTHLIB_CACHE_REDIS_DB = 0
          AUTHLIB_CACHE_KEY_PREFIX = None

    * filesystem: It caches things in local filesystem. Available
      configurations::

          AUTHLIB_CACHE_DIR = ''  # required
          AUTHLIB_CACHE_THRESHOLD = 500
    """
    def __init__(self, app, config_prefix='AUTHLIB', **kwargs):
        deprecate(DEPRECATE_MESSAGE, 0.7)

        self.config_prefix = config_prefix
        self.config = app.config

        cache_type = self._config('type')
        kwargs.update(
            dict(default_timeout=self._config('DEFAULT_TIMEOUT', 100)))

        if cache_type == 'null':
            self.cache = NullCache()
        elif cache_type == 'simple':
            kwargs.update(dict(threshold=self._config('threshold', 500)))
            self.cache = SimpleCache(**kwargs)
        elif cache_type == 'memcache':
            kwargs.update(
                dict(
                    servers=self._config('MEMCACHED_SERVERS'),
                    key_prefix=self._config('KEY_PREFIX', None),
                ))
            self.cache = MemcachedCache(**kwargs)
        elif cache_type == 'redis':
            kwargs.update(
                dict(
                    host=self._config('REDIS_HOST', 'localhost'),
                    port=self._config('REDIS_PORT', 6379),
                    password=self._config('REDIS_PASSWORD', None),
                    db=self._config('REDIS_DB', 0),
                    key_prefix=self._config('KEY_PREFIX', None),
                ))
            self.cache = RedisCache(**kwargs)
        elif cache_type == 'filesystem':
            kwargs.update(dict(threshold=self._config('threshold', 500), ))
            self.cache = FileSystemCache(self._config('DIR'), **kwargs)
        else:
            raise RuntimeError('`%s` is not a valid cache type!' % cache_type)
        app.extensions[config_prefix.lower() + '_cache'] = self.cache

    def _config(self, key, default=_missing):
        key = key.upper()
        prior = '%s_CACHE_%s' % (self.config_prefix, key)
        if prior in self.config:
            return self.config[prior]
        fallback = 'CACHE_%s' % key
        if fallback in self.config:
            return self.config[fallback]
        if default is _missing:
            raise RuntimeError('%s is missing.' % prior)
        return default

    def get(self, key):
        """Look up key in the cache and return the value for it.

        :param key: the key to be looked up.
        :returns: The value if it exists and is readable, else ``None``.
        """
        return self.cache.get(key)

    def delete(self, key):
        """Delete `key` from the cache.

        :param key: the key to delete.
        :returns: Whether the key existed and has been deleted.
        """
        return self.cache.delete(key)

    def get_many(self, *keys):
        """Returns a list of values for the given keys.
        For each key a item in the list is created::

            foo, bar = cache.get_many("foo", "bar")

        Has the same error handling as :meth:`get`.

        :param keys: The function accepts multiple keys as positional
                     arguments.
        """
        return [self.cache.get(k) for k in keys]

    def get_dict(self, *keys):
        """Like :meth:`get_many` but return a dict::

            d = cache.get_dict("foo", "bar")
            foo = d["foo"]
            bar = d["bar"]

        :param keys: The function accepts multiple keys as positional
                     arguments.
        """
        return self.cache.get_dict(*keys)

    def set(self, key, value, timeout=None):
        """Add a new key/value to the cache (overwrites value, if key already
        exists in the cache).

        :param key: the key to set
        :param value: the value for the key
        :param timeout: the cache timeout for the key in seconds (if not
                        specified, it uses the default timeout). A timeout of
                        0 idicates that the cache never expires.
        :returns: ``True`` if key has been updated, ``False`` for backend
                  errors. Pickling errors, however, will raise a subclass of
                  ``pickle.PickleError``.
        """
        return self.cache.set(key, value, timeout)

    def add(self, key, value, timeout=None):
        """Works like :meth:`set` but does not overwrite the values of already
        existing keys.

        :param key: the key to set
        :param value: the value for the key
        :param timeout: the cache timeout for the key in seconds (if not
                        specified, it uses the default timeout). A timeout of
                        0 idicates that the cache never expires.
        :returns: Same as :meth:`set`, but also ``False`` for already
                  existing keys.
        """
        return self.cache.add(key, value, timeout)

    def set_many(self, mapping, timeout=None):
        """Sets multiple keys and values from a mapping.

        :param mapping: a mapping with the keys/values to set.
        :param timeout: the cache timeout for the key in seconds (if not
                        specified, it uses the default timeout). A timeout of
                        0 idicates that the cache never expires.
        :returns: Whether all given keys have been set.
        """
        return self.cache.set_many(mapping, timeout)

    def delete_many(self, *keys):
        """Deletes multiple keys at once.

        :param keys: The function accepts multiple keys as positional
                     arguments.
        :returns: Whether all given keys have been deleted.
        :rtype: boolean
        """
        return self.cache.delete_many(*keys)

    def has(self, key):
        """Checks if a key exists in the cache without returning it. This is a
        cheap operation that bypasses loading the actual data on the backend.

        This method is optional and may not be implemented on all caches.

        :param key: the key to check
        """
        return self.cache.has(key)

    def clear(self):
        """Clears the cache.  Keep in mind that not all caches support
        completely clearing the cache.

        :returns: Whether the cache has been cleared.
        """
        return self.cache.clear()

    def inc(self, key, delta=1):
        """Increments the value of a key by `delta`.  If the key does
        not yet exist it is initialized with `delta`.

        For supporting caches this is an atomic operation.

        :param key: the key to increment.
        :param delta: the delta to add.
        :returns: The new value or ``None`` for backend errors.
        """
        return self.cache.inc(key, delta=delta)

    def dec(self, key, delta=1):
        """Decrements the value of a key by `delta`.  If the key does
        not yet exist it is initialized with `-delta`.

        For supporting caches this is an atomic operation.

        :param key: the key to increment.
        :param delta: the delta to subtract.
        :returns: The new value or `None` for backend errors.
        """
        return self.cache.dec(key, delta=delta)
示例#9
0
文件: cache.py 项目: dag/flask-cache
class Cache(object):
    """
    This class is used to control the cache objects.

    If TESTING is True it will use NullCache.
    """

    def __init__(self, app=None):
        self.cache = None

        if app is not None:
            self.init_app(app)
        else:
            self.app = None

    def init_app(self, app):
        "This is used to initialize cache with your app object"

        app.config.setdefault('CACHE_DEFAULT_TIMEOUT', 300)
        app.config.setdefault('CACHE_THRESHOLD', 500)
        app.config.setdefault('CACHE_KEY_PREFIX', None)
        app.config.setdefault('CACHE_MEMCACHED_SERVERS', None)
        app.config.setdefault('CACHE_DIR', None)
        app.config.setdefault('CACHE_TYPE', 'NullCache')

        self.app = app

        self._set_cache()

    def _set_cache(self):
        if self.app.config['TESTING']:
            self.cache = NullCache()
        else:
            if self.app.config['CACHE_TYPE'] == 'Null':
                self.cache = NullCache()
            elif self.app.config['CACHE_TYPE'] == 'Simple':
                self.cache = SimpleCache(
                    threshold=self.app.config['CACHE_THRESHOLD'],
                    default_timeout=self.app.config['CACHE_DEFAULT_TIMEOUT'])
            elif self.app.config['CACHE_TYPE'] == 'Memcached':
                self.cache = MemcachedCache(
                    self.app.config['CACHE_MEMCACHED_SERVERS'],
                    default_timeout=self.app.config['CACHE_DEFAULT_TIMEOUT'],
                    key_prefix=self.app.config['CACHE_KEY_PREFIX'])
            elif self.app.config['CACHE_TYPE'] == 'GAE':
                self.cache = GAEMemcachedCache(
                    default_timeout=self.app.config['CACHE_DEFAULT_TIMEOUT'],
                    key_prefix=self.app.config['CACHE_KEY_PREFIX'])
            elif self.app.config['CACHE_TYPE'] == 'FileSystem':
                self.cache = FileSystemCache(
                    self.app.config['CACHE_DIR'],
                    threshold=self.app.config['CACHE_THRESHOLD'],
                    default_timeout=self.app.config['CACHE_DEFAULT_TIMEOUT'])

    def get(self, *args, **kwargs):
        "Proxy function for internal cache object."
        return self.cache.get(*args, **kwargs)

    def set(self, *args, **kwargs):
        "Proxy function for internal cache object."
        self.cache.set(*args, **kwargs)

    def add(self, *args, **kwargs):
        "Proxy function for internal cache object."
        self.cache.add(*args, **kwargs)

    def delete(self, *args, **kwargs):
        "Proxy function for internal cache object."
        self.cache.delete(*args, **kwargs)

    def cached(self, timeout=None, key_prefix='view/%s', unless=None):
        """
        Decorator. Use this to cache a function. By default the cache key
        is `view/request.path`. You are able to use this decorator with any
        function by changing the `key_prefix`. If the token `%s` is located
        within the `key_prefix` then it will replace that with `request.path`

        Example::

            # An example view function
            @cache.cached(timeout=50)
            def big_foo():
                return big_bar_calc()

            # An example misc function to cache.
            @cache.cached(key_prefix='MyCachedList')
            def get_list():
                return [random.randrange(0, 1) for i in range(50000)]

        .. code-block:: pycon

            >>> my_list = get_list()

        :param timeout: Default None. If set to an integer, will cache for that
                        amount of time.
        :param key_prefix: Default 'view/%(request.path)s'. Beginning key to .
                           use for the cache key.
        :param unless: Default None. Cache will *always* execute the caching
                       facilities unless this callable is true.
                       This will bypass the caching entirely.
        """

        def decorator(f):

            @wraps(f)
            def decorated_function(*args, **kwargs):
                #: Bypass the cache entirely.
                if callable(unless) and unless() is True:
                        return f(*args, **kwargs)

                if '%s' in key_prefix:
                    cache_key = key_prefix % request.path
                else:
                    cache_key = key_prefix

                rv = self.cache.get(cache_key)
                if not rv or current_app.debug:
                    rv = f(*args, **kwargs)
                    self.cache.set(cache_key, rv, timeout=timeout)
                return rv
            return decorated_function
        return decorator

    def memoize(self, timeout=None):
        """
        Use this to cache the result of a function, taking its arguments into
        account in the cache key.

        Information on
        `Memoization <http://en.wikipedia.org/wiki/Memoization>`_.

        Example::

            @cache.memoize(timeout=50)
            def big_foo(a, b):
                return a + b + random.randrange(0, 1000)

        .. code-block:: pycon

            >>> big_foo(5, 2)
            753
            >>> big_foo(5, 3)
            234
            >>> big_foo(5, 2)
            753

        :param timeout: Default None. If set to an integer, will cache for that
                        amount of time.
        """

        def memoize(f):

            @wraps(f)
            def decorated_function(*args, **kwargs):
                cache_key = (f.__name__, id(f), args, str(kwargs))

                rv = self.cache.get(cache_key)
                if rv is None:
                    rv = f(*args, **kwargs)
                    self.cache.set(cache_key, rv)
                return rv
            return decorated_function
        return memoize
示例#10
0
class FileSystemSessionInterface(SessionInterface):
    """Uses the :class:`werkzeug.contrib.cache.FileSystemCache` as a session
    backend.

    .. versionadded:: 0.2
        The `use_signer` parameter was added.

    :param cache_dir: the directory where session files are stored.
    :param threshold: the maximum number of items the session stores before it
                      starts deleting some.
    :param mode: the file mode wanted for the session files, default 0600
    :param key_prefix: A prefix that is added to FileSystemCache store keys.
    :param use_signer: Whether to sign the session id cookie or not.
    """

    session_class = FileSystemSession

    def __init__(self, cache_dir, threshold, mode, key_prefix,
                 use_signer=False):
        from werkzeug.contrib.cache import FileSystemCache
        self.cache = FileSystemCache(cache_dir, threshold=threshold, mode=mode) #FileSystemCache是从上句导入的,threshold代表最多纪录条数
        self.key_prefix = key_prefix
        self.use_signer = use_signer

    def open_session(self, app, request):
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            sid = self._generate_sid()
            return self.session_class(sid=sid)
        if self.use_signer:
            signer = self._get_signer(app)
            if signer is None:
                return None
            try:
                sid = signer.unsign(sid)
            except BadSignature:
                sid = None

        data = self.cache.get(self.key_prefix + sid)    #这是根据session_id获取session值
        if data is not None:
            return self.session_class(data, sid=sid)
        return self.session_class(sid=sid)
    
    def save_session(self, app, session, response):
        domain = self.get_cookie_domain(app)
        path = self.get_cookie_path(app)
        if not session:     #验证过了,就是判断session是否为空(空字典)
            if session.modified:
                self.cache.delete(self.key_prefix + session.sid)
                response.delete_cookie(app.session_cookie_name,
                                       domain=domain, path=path)
            return

        # Modification case.  There are upsides and downsides to
        # emitting a set-cookie header each request.  The behavior
        # is controlled by the :meth:`should_set_cookie` method
        # which performs a quick check to figure out if the cookie
        # should be set or not.  This is controlled by the
        # SESSION_REFRESH_EACH_REQUEST config flag as well as
        # the permanent flag on the session itself.
        #if not self.should_set_cookie(app, session):
        #    return

        httponly = self.get_cookie_httponly(app)
        secure = self.get_cookie_secure(app)
        expires = self.get_expiration_time(app, session)
        #data = dict(session)
        #self.cache.set(self.key_prefix + session.sid, data,
        #                 int(app.permanent_session_lifetime.total_seconds()))
        if self.use_signer: #签名加密
            session_id = self._get_signer(app).sign(session.sid)
        else:
            session_id = session.sid
        response.set_cookie(app.session_cookie_name, session_id,
                            expires=expires, httponly=httponly,
                            domain=domain, path=path, secure=secure)

    
    def save_session_without_response(self, app, session):

        #httponly = self.get_cookie_httponly(app)
        #secure = self.get_cookie_secure(app)
        #expires = self.get_expiration_time(app, session)
        data = dict(session)
        self.cache.set(self.key_prefix + session.sid, data,    
                     int(app.permanent_session_lifetime.total_seconds()))

    def judge_attack(self, app, request):   #判断两次间隔的访问是否大于三秒
        sid = request.cookies.get(app.session_cookie_name)
        if not sid:
            return False
        current_time = time.time()
        try:
            last_time = self.cache.get(self.key_prefix + sid)['time']    #这是根据session_id获取session值
        except:
            return False
        if current_time-last_time < 3:
            return True
        return False