OMcache is a C and Python library for accessing memcached servers. The goals of the OMcache project are a stable API and ABI and 'easy' integration into complex applications and systems. OMcache is meant to be used as a middleware layer to provide redundancy and consistency to a memcached server cluster. OMcache specifically tries to avoid ABI brekage and does not mask any signals or call blocking functions to help integrating it into other solutions.
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OMcache tries to be compatible with libmemcached where possible. During normal operations where all servers are available and no failovers have happened the two memcache clients should always select the same servers for keys. Libmemcached's failover mechanism has traditionally been poorly documented and its details have changed occasionally between the releases so 100% compatibility is not possible.
The default KETAMA implementation was changed in libmemcached 1.0.10. OMcache defaults to the new algorithm but also has support for the older algorithm, the caller must select the older algorithm if compatibility with older libmemcached versions is required.
OMcache also provides a thin API compatibility wrapper header which allows simple applications to be converted to use OMcache instead of libmemcached by including "omcache_libmemcached.h" instead of "libmemcached/memcached.h". Similarly there's a compatibility layer for pylibmc in omcache_pylibmc.py which provides a limited pylibmc-like API for OMcache.
The functionality provided by these wrappers is limited and they are not supported, they're provided to make it easy to test OMcache in simple programs that use the libmemcached or pylibmc API.
OMcache is released under the Apache License, Version 2.0.
For the exact license terms, see LICENSE and http://opensource.org/licenses/Apache-2.0 .
OMcache was created and is maintained by Oskari Saarenmaa <[email protected]>.
F-Secure Corporation provided the infrastructure for testing OMcache in its initial development process and contributed to the pylibmc and libmemcached compatibility layers as well as ported pgmemcache (PostgreSQL memcached interface) to run on OMcache.
MD5 implementation is based on Solar Designer's Public Domain / BSD licensed code from openwall.info.
Bug reports and patches are very welcome, please post them as GitHub issues and pull requests at https://github.com/saaros/omcache