rdlm-py

Status (master branch)

What is it ?

rdlm-py is a python client for the restful-distributed-lock-manager (RDLM).

Special features

• Classic and administrative (password protected) requests
• Three ways to use it (a classical API, a (more pythonic) ContextManager API, some CLI tools)

Warning

rdlm-py is at an early stage of development (API can change).

Quickstart

Installation

pip install rdlm-py

Requirements: 
- Python 2.6, 2.7, 3.2 or 3.3
- Requests >= 1.2.3

Three ways to use it

Classic API

# Import the Classic client class
from rdlmpy import RDLMClient
from rdlmpy import RDLMException

# Make a client object with some default parameters
client = RDLMClient(server="localhost", port=8888, default_title="classic example", default_lifetime=300, default_wait=10)

# Acquire a lock on resource : foo
lock_url = client.lock_acquire("foo")

# We have the lock on resource : foo
# [...]

# Try to acquire the same lock another time with a overrided wait timeout of 3 seconds
# => RDLMException 
try:
    lock_url2 = client.lock_acquire("foo", wait=3)
except RDLMException:
    print "Can't acquire the lock"

# Release the lock
result = client.lock_release(lock_url)
if not(result):
    print "Can't release the lock"

Context Manager API

# Import the Context Manager class class
from rdlmpy import RDLMContextManager

with RDLMContextManager("foo") as c:
    # We have the lock on resource: foo
    # [...]
    # No need to release the lock, even if an exception is raised

# Here, we don't have the lock anymore
# [...]

CLI tools

Some CLI tools are available :

• lock-acquire.py: acquire a lock
• lock-release.py: release a lock
• lock-get.py: get some informations about lock
• lock-list-resources.py: list all resources
• lock-list-locks.py: list all locks for a given resource

Example in a shell script :

#!/bin/bash

LOCK_URL=`lock-acquire.py foo`
if test $? -ne 0; then
    exit 1
fi

[...] 

lock-release.py ${LOCK_URL}

Full manual (lock-acquire.py):

usage: lock-acquire.py [-h] [-H HOSTNAME] [-p PORT] [-t TIMEOUT] [-w WAIT]
                    resource_name

Acquire a lock

positional arguments:
resource_name         Resource Name

optional arguments:
-h, --help            show this help message and exit
-H HOSTNAME, --hostname HOSTNAME
                    rdlm server hostname
-p PORT, --port PORT  rdlm server port
-t TIMEOUT, --timeout TIMEOUT
                    timeout of the lock if acquired and not released
                    (seconds)
-w WAIT, --wait WAIT  max number of seconds to wait for the lock

Full manual (lock-release.py):

usage: lock-release.py [-h] lock_url

Release a lock

positional arguments:
lock_url    Lock Url (returned by lock-acquire.py)

optional arguments:
-h, --help  show this help message and exit

Full manual (lock-get.py):

usage: lock-get.py [-h] lock_url

Get some informations about a lock

positional arguments:
lock_url    Lock Url (returned by lock-acquire.py)

optional arguments:
-h, --help  show this help message and exit

Full manual (lock-list-resources.py):

usage: lock-list-resources.py [-h] [-H HOSTNAME] [-p PORT] [-u USERNAME]
                            [-P PASSWORD]

List all resources (with locks)

optional arguments:
-h, --help            show this help message and exit
-H HOSTNAME, --hostname HOSTNAME
                        rdlm server hostname
-p PORT, --port PORT  rdlm server port
-u USERNAME, --username USERNAME
                        Administrative username
-P PASSWORD, --password PASSWORD
                        Administrative password

Full manual (lock-list-locks.py):

usage: lock-list-locks.py [-h] [-H HOSTNAME] [-p PORT] [-u USERNAME]
                        [-P PASSWORD]
                        resource_name

List all resources (with locks)

positional arguments:
resource_name         Resource Name

optional arguments:
-h, --help            show this help message and exit
-H HOSTNAME, --hostname HOSTNAME
                        rdlm server hostname
-p PORT, --port PORT  rdlm server port
-u USERNAME, --username USERNAME
                        Administrative username
-P PASSWORD, --password PASSWORD
                        Administrative password