Package gluon :: Module cache :: Class CacheOnDisk

Class CacheOnDisk

   object --+    
            |    
CacheAbstract --+
                |
               CacheOnDisk

Disk based cache

This is implemented as a shelve object and it is shared by multiple web2py processes (and threads) as long as they share the same filesystem. The file is locked when accessed.

Disk cache provides persistance when web2py is started/stopped but it slower than `CacheInRam`

Values stored in disk cache must be pickable.

Instance Methods

[hide private]

__call__(self, key, f, time_expire=300)
Tries retrieve the value corresponding to `key` from the cache of the object exists and if it did not expire, else it called the function `f` and stores the output in the cache corresponding to `key`.

source code

__init__(self, request=None, folder=None)
Parameters...

source code

_close_shelve_and_unlock(self)

source code

_open_shelve_and_lock(self)
Open and return a shelf object, obtaining an exclusive lock on self.locker first.

source code

clear(self, regex=None)
Clears the cache of all keys that match the provided regular expression.

source code

increment(self, key, value=1)
Increments the cached value for the given key by the amount in value

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initialize(self)

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Inherited from CacheAbstract (private): _clear

Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __repr__, __setattr__, __sizeof__, __str__, __subclasshook__

Class Variables

[hide private]

Inherited from CacheAbstract: cache_stats_name

Properties

[hide private]

Inherited from object: __class__

Method Details

[hide private]

call(self, key, f, time_expire=300)
(Call operator)

source code


Tries retrieve the value corresponding to `key` from the cache of the
object exists and if it did not expire, else it called the function `f`
and stores the output in the cache corresponding to `key`. In the case
the output of the function is returned.

:param key: the key of the object to be store or retrieved
:param f: the function, whose output is to be cached
:param time_expire: expiration of the cache in microseconds

- `time_expire` is used to compare the current time with the time when
    the requested object was last saved in cache. It does not affect
    future requests.
- Setting `time_expire` to 0 or negative value forces the cache to
    refresh.

If the function `f` is `None` the cache is cleared.

Overrides: CacheAbstract.__call__: (inherited documentation)

init(self, request=None, folder=None)
(Constructor)

source code


Parameters
----------
request:
    the global request object

Overrides: object.__init__: (inherited documentation)

_open_shelve_and_lock(self)

source code

Open and return a shelf object, obtaining an exclusive lock on self.locker first. Replaces the close method of the returned shelf instance with one that releases the lock upon closing.

clear(self, regex=None)

source code


Clears the cache of all keys that match the provided regular expression.
If no regular expression is provided, it clears all entries in cache.

Parameters
----------
regex:
    if provided, only keys matching the regex will be cleared.
    Otherwise all keys are cleared.

Overrides: CacheAbstract.clear: (inherited documentation)

increment(self, key, value=1)

source code


Increments the cached value for the given key by the amount in value

Parameters
----------
key:
    key for the cached object to be incremeneted
value:
    amount of the increment (defaults to 1, can be negative)

Overrides: CacheAbstract.increment: (inherited documentation)

Class CacheOnDisk

__call__(self, key, f, time_expire=300) (Call operator)

__init__(self, request=None, folder=None) (Constructor)

_open_shelve_and_lock(self)

clear(self, regex=None)

increment(self, key, value=1)

call(self, key, f, time_expire=300)
(Call operator)

init(self, request=None, folder=None)
(Constructor)