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klepto: persistent caching to memory, disk, or database
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About Klepto
============

`klepto` extends python's `lru_cache` to utilize different keymaps and
alternate caching algorithms, such as `lfu_cache` and `mru_cache`.
While caching is meant for fast access to saved results, `klepto` also
has archiving capabilities, for longer-term storage. `klepto` uses a
simple dictionary-sytle interface for all caches and archives, and all
caches can be applied to any python function as a decorator. Keymaps
are algorithms for converting a function's input signature to a unique
dictionary, where the function's results are the dictionary value.
Thus for `y = f(x)`, `y` will be stored in `cache[x]` (e.g. `{x:y}`).

`klepto` provides both standard and 'safe' caching, where safe caches
are slower but can recover from hashing errors. `klepto` is intended
to be used for distributed and parallel computing, where several of
the keymaps serialize the stored objects. Caches and archives are
intended to be read/write accessible from different threads and
processes. `klepto` enables a user to decorate a function, save the
results to a file or database archive, close the interpreter,
start a new session, and reload the function and it's cache.

`klepto` is part of `pathos`, a python framework for heterogenous computing.
`klepto` is in active development, so any user feedback, bug reports, comments,
or suggestions are highly appreciated.  A list of known issues is maintained
at http://trac.mystic.cacr.caltech.edu/project/pathos/query, with a public
ticket list at https://github.com/uqfoundation/klepto/issues.


Major Features
==============

`klepto` has standard and 'safe' variants of the following::

    - `lfu_cache` - the least-frequently-used caching algorithm
    - `lru_cache` - the least-recently-used caching algorithm
    - `mru_cache` - the most-recently-used caching algorithm
    - `rr_cache` - the random-replacement caching algorithm
    - `no_cache` - a dummy caching interface to archiving
    - `inf_cache` - an infinitely-growing cache

`klepto` has the following archive types::

    - `file_archive` - a dictionary-style interface to a file
    - `dir_archive` - a dictionary-style interface to a folder of files
    - `sqltable_archive` - a dictionary-style interface to a sql database table
    - `sql_archive` - a dictionary-style interface to a sql database
    - `dict_archive` - a dictionary with an archive interface
    - `null_archive` - a dictionary-style interface to a dummy archive 

`klepto` provides the following keymaps::

    - `keymap` - keys are raw python objects
    - `hashmap` - keys are a hash for the python object
    - `stringmap` - keys are the python object cast as a string
    - `picklemap` - keys are the serialized python object

`klepto` also includes a few useful decorators providing::

    - simple, shallow, or deep rounding of function arguments
    - cryptographic key generation, with masking of selected arguments


Current Release
===============

This version is `klepto-0.1.4`.

The latest released version of `klepto` is available from::

    http://trac.mystic.cacr.caltech.edu/project/pathos

or::

    https://github.com/uqfoundation/klepto/releases

or also::

    https://pypi.python.org/pypi/klepto

`klepto` is distributed under a 3-clause BSD license.

    >>> import klepto
    >>> print (klepto.license())


Development Version 
===================

You can get the latest development version with all the shiny new features at::

    https://github.com/uqfoundation

If you have a new contribution, please submit a pull request.


Installation
============

`klepto` is packaged to install from source, so you must
download the tarball, unzip, and run the installer::

    [download]
    $ tar -xvzf klepto-0.1.4.tgz
    $ cd klepto-0.1.4
    $ python setup py build
    $ python setup py install

You will be warned of any missing dependencies and/or settings
after you run the "build" step above. 

Alternately, `klepto` can be installed with `pip` or `easy_install`::

    $ pip install klepto


Requirements
============

`klepto` requires::

    - python2, version >= 2.5  *or*  python3, version >= 3.1  *or*  pypy
    - dill, version >= 0.2.7
    - pox, version >= 0.2.3

Optional requirements::

    - sqlalchemy, version >= 0.8.4
    - setuptools, version >= 0.6


More Information
================

Probably the best way to get started is to look at the tests
that are provide within `klepto`. See `klepto.tests` for a set of scripts
that test the caching and archiving functionalities in `klepto`. The
source code is also generally well documented, so further questions may
be resolved by inspecting the code itself. Please also feel free to submit
a ticket on github, or ask a question on stackoverflow (@Mike McKerns).

`klepto` is an active research tool. There are a growing number of publications
and presentations that discuss real-world examples and new features of `klepto`
in greater detail than presented in the user's guide.  If you would like to
share how you use `klepto` in your work, please post a link or send an email
(to mmckerns at uqfoundation dot org).


Citation
========

If you use `klepto` to do research that leads to publication, we ask that you
acknowledge use of `klepto` by citing the following in your publication::

    Michael McKerns and Michael Aivazis,
    "pathos: a framework for heterogeneous computing", 2010- ;
    http://dev.danse.us/trac/pathos

Please see http://trac.mystic.cacr.caltech.edu/project/pathos for
further information.

