FriendlyDB

friendlydb is a small & fast following/followers database written in Python. It can be either used directly from your Python code or over HTTP with small web API.

FriendlyDB isn't meant to be a full user system; it should be used to augment an existing system to track relationships.

WARNING

Starting with v2.0.0, FriendlyDB is NOT backward-compatible with v0.4.0 & before. Prior to v2.0.0, data was stored on the filesystem, but in v2.0.0 & later, data is stored in Redis.

It was rewritten to use Redis for several reasons:

• Better performance
• Less wear/tear on hard disks
• Simpler code

However, this does mean you will need to run your own version of the Redis server (2.6.4+ recommended).

See below if you need to migrate from an older install to v2.0.0.

Usage

Using FriendlyDB from Python looks like:

from friendlydb.db import FriendlyDB

# Start using the DB (assumes Redis default host/port/db).
fdb = FriendlyDB()
# Alternatively, ``fdb = FriendlyDB(host='127.0.0.2', port=7100, db=3)``

# Grab a user by their username.
daniel = fdb['daniel']

# Follow a couple users.
daniel.follow('alice')
daniel.follow('bob')
daniel.follow('joe')

# Check the following.
daniel.following()
# Returns:
# [
#     'alice',
#     'bob',
#     'joe',
# ]

# Check joe's followers.
fdb['joe'].followers()
# Returns:
# [
#     'daniel',
# ]

# Unfollow.
daniel.unfollow('bob')

# Check the following.
daniel.following()
# Returns:
# [
#     'alice',
#     'joe',
# ]

# Dust off & nuke everything from orbit.
fdb.clear()

Using FriendlyDB from HTTP looks like (all trailing slashes are optional):

# In one shell, start the server.
python friendlydb/server.py -d /tmp/friendly

# From another, run some URLs.
curl -X GET http://127.0.0.1:8008/
# {"version": "0.3.0"}

curl -X GET http://127.0.0.1:8008/daniel/
# {"username": "daniel", "following": [], "followers": []}

curl -X POST http://127.0.0.1:8008/daniel/follow/alice/
# {"username": "daniel", "other_username": "alice", "followed": true}
curl -X POST http://127.0.0.1:8008/daniel/follow/bob/
# {"username": "daniel", "other_username": "bob", "followed": true}
curl -X POST http://127.0.0.1:8008/daniel/follow/joe/
# {"username": "daniel", "other_username": "joe", "followed": true}

curl -X POST http://127.0.0.1:8008/daniel/unfollow/joe/
# {"username": "daniel", "other_username": "joe", "unfollowed": true}

curl -X GET http://127.0.0.1:8008/daniel/
# {"username": "daniel", "following": ["alice", "bob"], "followers": []}

curl -X GET http://127.0.0.1:8008/daniel/is_following/alice/
# {"username": "daniel", "other_username": "alice", "is_following": true}

curl -X GET http://127.0.0.1:8008/alice/is_followed_by/daniel/
# {"username": "alice", "other_username": "daniel", "is_followed_by": true}

curl -X GET http://127.0.0.1:8008/alice/is_followed_by/joe/
# {"username": "alice", "other_username": "joe", "is_followed_by": false}

Requirements

• Python 2.6+ or Python 3.3+
• redis.py >= 2.7.2
• (Optional) gevent for the HTTP server
• (Optional) unittest2 for running tests

Installation

Using pip, you can install it with pip install friendlydb.

Performance

You can scope out FriendlyDB's performance for yourself by running the included benchmark.py script.

In tests on a 2011 MacBook Pro (i7), the benchmark script demonstrated:

• created 1,000,000 relationships between 10,000 users: 179 seconds (~2.5X faster than 0.4.0)
• avg time to fetch a user's followers: 0.0016 seconds
• never exceeding 41Mb of RAM RSS

Migrating from v0.4.0 to 2.0.0

First, install & run the Redis server.

Second, run pip install redis>=2.7.2.

To migrate your data, the easiest way is to leave your old install of FriendlyDB in place (using the HTTP server), create a new install w/ Redis, then run code like:

import requests
import json
# The new version.
from friendlydb import FriendlyDB

old_url = 'http://127.0.0.1:8008/'
fdb = FriendlyDB()

for username in users:
    user = fdb[username]

    # Following.
    resp = requests.get("{0}/{1}/following/".format(old_url, username))
    data = json.loads(resp.content)

    for f_username in data.get("following", []):
        user.follow(f_username)

You should create your own script & verify your data post-migration. No promises are made about the effectiveness/accuracy of the above code.

Running Tests

friendlydb is maintained with passing tests at all times. Simply run:

python -m unittest2 tests

Contributions

In order for a contribution to be considered for merging, it must meet the following requirements:

• Patch cleanly solves the problem
• Added test coverage (now passing) to expose the bug & check for regression
• If the behavior affects end-users, there must be docs on the changes
• The patch/tests must be compatibly licensed with New BSD

The best way to submit contributions is by forking the project on Github, applying your changes on a new branch, pushing those changes back to GH & submitting a pull request through the GitHub interface.

License

New BSD license.

author:	Daniel Lindsley
version:	2.0.0
date:	2013-01-17