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Developer Notes

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Ouziel Slama edited this page Mar 23, 2015 · 23 revisions

Installation:

  • Python2.7 is required

pip install -r requirements.txt

That will try to install the requirements in your current environment.

NOTE: If you have not setup a virtualenv this will most likely try to install dependencies globally and might require more privileges.

In case you want to avoid messing with your global environment, you can use Buildout (optional).

How to contribute

We accept pull requests. Fork the repository and send your PR!

dev_requirements

To install the dependencies necessary for development (testing, ...), run:

pip install -r dev_requirements.txt

Coding

  • You should try to write code compatible with Python3 (see http://www.diveintopython3.net/porting-code-to-python-3-with-2to3.html).
  • Your code should pass PEP8 check.
  • Use absolute path for import (eg. from pyethereum import utils)
  • Use rlp.utils.decode_hex and rlp.utils.encode_hex instead of .decode('hex') and .encode('hex')
  • Use utils.is_numeric() and utils.is_string() instead of isinstance()
  • Use utils.to_string() instead str()
  • Use rlp.utils.ascii_chr() instead chr()
  • Use utils.safe_ord() instead ord()
  • Use // instead / to divide integer
  • Use bytes for every hard coded string

Testing

pytest is used for testing

In order to run tests, you need to prepare the fixtures-submodule (not necessary when using bootstrap):

git submodule init
git submodule update --recursive

then run the tests either by calling py.test (or behave for a set of older tests) consecutively or by calling tox (which will do both).

In order to update the fixtures-submodule:

git submodule status
cd fixtures/
git pull origin develop
cd ..
git commit -m 'updated fixtures submodule'

Tips for testing with the VM:

  1. You can get traces for a transaction using the API and ethclient, e.g.: bin/pyethclient trace 522f583b94cb3a16deca41404ef404c2c1b3484070af2ec7971bc4e1a17c556e
  2. Use the -s modifier to see the log output of tests, e.g. py.test -s tests/test_vm.py
  3. You can customize the level of VM logging detail by modifying PBLogger in processblock.py

Logging:

Please use the logging module for logging.

For basic, verbose logging functionality, the following is sufficient (adjust level to your needs)::

import logging

logging.basicConfig(format='[%(asctime)s] %(name)s %(levelname)s %(message)s', level=logging.DEBUG)
logger = logging.getLogger(__name__)

If you need a more advanced setup, have a look at the python docs

Easy Debugging:

The eth.py script, understands a command line flag for easy debugging, e.g.:

pyethereum/eth.py -L pyethereum.wire:DEBUG,:INFO ...<other args>

will set the log-level for wire to DEBUG and the root logger to INFO.

pyethereum/eth.py -L :DEBUG ...<other args>

logs everything to the console.

Monkey patching

bin/pyeth tries to import a module named pyethereum/monkeypatch.py. You can use monkey patching to temporarily introduce alternate control flow e.g.

"Monkey Patch Example"

import pyethereum.packeter
pyethereum.packeter.Packeter.CLIENT_VERSION += '/YourName'

# set processblock log details
import pyethereum.processblock as pb
pb.pblogger.log_state_delta = True
pb.pblogger.log_ops = True

# write failed blocks to disc
import pyethereum.utils as utils
orig_verify = pb.verify

def log_verify(block, parent):
   res = orig_verify(block, parent)
   if not res:
        pb.logger.debug('### VERIFICATION FAILED ### %r', e)
        f = os.path.join(utils.data_dir, 'badblock.log')
        open(f, 'w').write(str(block.hex_serialize()))
        print block.hex_serialize()
    return res
pb.verify = log_verify

# import other patches
import blockfetcherpatch

Installation with Buildout

You can have dependencies managed by buildout - a buildout.cfg is already included in the project.

Bootstrap:

In order to do so, you'll need to bootstrap the project (needs only be done once). On systems that provide curl you can use the following handy one-liner (no curl_ ?):

curl http://downloads.buildout.org/2/bootstrap.py | python

Build and run:

Build the project via bin/buildout and run the client via bin/eth.

This will install dependencies in a virtualenv, provide you with a scoped python interpreter (bin/python) and make all console_scripts available in the bin directory.

develop.cfg

Instead of only running bin/buildout, there is an extending buildout configuration for development purposes (it will install the dev_requirements, prepare tests, etc...). It is an executable .cfg file:

./develop.cfg

will run the extended buildout.

Hints:

console-scripts

If you follow the buildout way, some of the commands in this README will change, since buildout installs the dependencies as well as pyethereum's console_scripts in the bin/-directory. For example, instead of running the cli client with:

pyethereum/eth.py # it will become
bin/eth

same goes for behave which becomes bin/behave.

no curl

If your system has wget and not curl you can also use wget -O - in place of curl. Otherwise download the bootstrap script into the project folder and call python bootstrap.py. (If you get setuptools issue, try python bootstrap.py -v 2.1.1)

buildout default.cfg

To prevent buildout from cluttering your working directory with an eggs/ directory, you should consider using a ~/.buildout/default.cfg:

export "BDIR=$HOME/.buildout"
mkdir -p $BDIR/eggs $BDIR/extends $BDIR/cache
echo "[buildout]" >> $BDIR/default.cfg
echo "eggs-directory = $BDIR/eggs" >> $BDIR/default.cfg
echo "download-cache = $BDIR/cache" >> $BDIR/default.cfg
echo "extends-cache = $BDIR/extends" >> $BDIR/default.cfg

After doing that, cleaning your clone with git clean -xfd and redoing the Bootstrap part is recommended.

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