Ethereum Bloom Filter

A python implementation of the bloom filter used by Ethereum.

This library and repository was previously located at https://github.com/pipermerriam/ethereum-bloom. It was transferred to the Ethereum foundation github in November 2017 and renamed to eth-bloom. The PyPi package was also renamed from ethereum-bloom to `eth-bloom.

For more information on what Ethereum Bloom Filters are see here.

Installation

$ pip install eth-bloom

Development

pip install -e ".[dev]"

Running the tests

You can run the tests with:

pytest tests

Or you can install tox to run the full test suite.

Releasing

To release a new version:

make release bump={bumpversion}

How to bumpversion

The version format for this repo is {major}.{minor}.{patch} for stable, and {major}.{minor}.{patch}-{stage}.{devnum} for unstable (stage can be alpha or beta).

To issue the next version in line, use bumpversion and specify which part to bump, like bumpversion minor or bumpversion devnum.

If you are in a beta version, bumpversion stage will switch to a stable.

To issue an unstable version when the current version is stable, specify the new version explicitly, like bumpversion --new-version 4.0.0-alpha.1 devnum

Usage

The BloomFilter object

>>> from eth_bloom import BloomFilter
>>> b = BloomFilter()
>>> b'a value' in b  # check whether a value is present
False
>>> b.add(b'a value')  # add a single value
>>> b'a value' in b
True
>>> int(b)  # cast to an integer
3458628712844765018311492773359360516229024449585949240367644166080576879632652362184119765613545163153674691520749911733485693171622325900647078772681584616740134230153806267998022370194756399579977294154062696916779055028045657302214591620589415314367270329881298073237757853875497241510733954508399863880080986777555986663988492288946856978031023631618215522505971170427986911575695114157059398791122395379400594948096
>>> bin(b)  # cast to a binary string
'0b100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'

You can also add an iterable of items to a bloom filter.

>>> b = BloomFilter()
>>> b'value-a' in b
False
>>> b'value-b' in b
False
>>> b.extend([b'value-a', b'value-b'])
>>> b'value-a' in b
True
>>> b'value-b' in b
True

You can initialize a bloom filter from an iterable of byte strings.

>>> b = BloomFilter.from_iterable([b'value-a', b'value-b'])  # initialize from an iterable of values.
>>> b'value-a' in b
True
>>> b'value-b' in b
True

You can initialize a bloom filter from the integer representation of the bloom bits.

>>> b = BloomFilter(3458628712844765018311492773359360516229024449585949240367644166080576879632652362184119765613545163153674691520749911733485693171622325900647078772681584616740134230153806267998022370194756399579977294154062696916779055028045657302214591620589415314367270329881298073237757853875497241510733954508399863880080986777555986663988492288946856978031023631618215522505971170427986911575695114157059398791122395379400594948096)
>>> b'a value' in b
True

You can also merge bloom filters

>>> from eth_bloom import BloomFilter
>>> b1 = BloomFilter()
>>> b2 = BloomFilter()
>>> b1.add(b'a')
>>> b1.add(b'common')
>>> b2.add(b'b')
>>> b2.add(b'common')
>>> b'a' in b1
True
>>> b'b' in b1
False
>>> b'common' in b1
True
>>> b'a' in b2
False
>>> b'b' in b2
True
>>> b'common' in b2
True
>>> b3 = b1 + b2  # using addition
>>> b'a' in b3
True
>>> b'b' in b3
True
>>> b'common' in b3
True
>>> b4 = b1 | b2  # or using bitwise or
>>> b'a' in b4
True
>>> b'b' in b4
True
>>> b'common' in b4
True
>>> b1 |= b2  # or using in-place operations (works with += too)
>>> b'a' in b1
True
>>> b'b' in b1
True
>>> b'common' in b1
True