CDBx - CDB Reimplementation for Python
cdbx is a CDB reimplementation for Python.
Supported python versions are Python 2.7 and Python 3.3 and above.
Documentation
Documentation Search (needs javascript)
API Documentation (generated)
Examples
Note that everything going in and out of the CDB is bytes. This is more relevant for Python 3. Keys and values which are passed as (unicode) strings, are converted to bytes using the latin-1 codec. However, keys and values retrieved from the CDB are always bytes.
# simple file write
import cdbx
cdb = cdbx.CDB.make('somefile')
cdb.add('key', 'value')
# ...
cdb = cdb.commit()
print(cdb['key'])
# atomic file write (original cdbmake behaviour)
import os
import cdbx
cdb = cdbx.CDB.make('somefile.tmp')
cdb.add('key', 'value')
# ...
cdb.commit().close()
os.rename('somefile.tmp', 'somefile')
cdb = cdbx.CDB('somefile')
print(cdb['key'])
# CDB within tempfile
import tempfile
import cdbx
cdb = cdbx.CDB.make(tempfile.TemporaryFile())
cdb.add('key', 'value')
# ...
cdb = cdb.commit()
print(cdb['key'])
cdb.close() # or going out-of-scope, or del cdb
# now it's gone
print(cdb['key'])
IOError: I/O operation on a closed file
Rationale, Advocacy, Key Features
CDB as a concept is a great idea for various reasons. It’s fast, it’s a simple, portable file format and all operations can be done using one open file descriptor.
There are, of course, other interfaces to CDB (most notably python-cdb, which I have been using for a long time).
cdbx tries to solve a few problems with those for me:
support for Python 3
better interface for CDB creation - you only need a file descriptor if you want to. This is important if you want to create a CDB within a single temporary file.
all operations are independent from each other (multiple accesses at the same time are possible). Thanks to the GIL it should be even thread safe. This has not been tested yet, though.
more natural interface for the main CDB class in general
better error handling (especially with regard to python) in some places
Since it’s a complete reimplementation, the licensing issue (people claim to have with public domain software [cdb]) does not apply.
Development Status
Beta.
There are some features to add and some cleanups to do before a stable release.
License
cdbx is available under the terms and conditions of the “Apache License, Version 2.0.” You’ll find the detailed licensing terms in the root directory of the source distribution package or online at http://www.apache.org/licenses/LICENSE-2.0.
Bugs
No bugs, of course. ;-) But if you’ve found one or have an idea how to improve cdbx, feel free to send a pull request on github or send a mail to <cdbx-bugs@perlig.de>.