lockable

Resource locking module for python.

Originally designed for following projects:

• pytest-lockable
• robot-lockable

Module provides python API and simple CLI interface.

Resource is released in following cases:

• process ends
• when context ends when lockable.auto_lock(..) is used
• allocation.unlock() is called
• lockable.unlock() is called

Resources data provider support following mechanisms:

• resources.json file in file system
• python list of dictionaries
• http uri which points to API and is used with HTTP GET method. API should provide resources.json data as json object.

CLI interface

% lockable --help
usage: lockable [-h] [--validate-only] [--lock-folder LOCK_FOLDER] [--resources RESOURCES]
                [--timeout TIMEOUT] [--hostname HOSTNAME]
                [--requirements REQUIREMENTS]
                [command [command ...]]

run given command while suitable resource is allocated.
Usage example: lockable --requirements {"online":true} echo using resource: $ID

positional arguments:
  command               Command to be execute during device allocation

optional arguments:
  -h, --help            show this help message and exit
  --validate-only       Only validate resources.json
  --lock-folder LOCK_FOLDER
                        lock folder
  --resources RESOURCES
                        Resources file (utf-8) or http uri
  --timeout TIMEOUT     Timeout for trying allocate suitable resource
  --hostname HOSTNAME   Hostname
  --requirements REQUIREMENTS
                        requirements as json string

API's

Constructor

lockable = Lockable([hostname], [resource_list_file], [resource_list], [lock_folder])

Allocation

allocation_context = lockable.lock(requirements, [timeout_s])
print(allocation_context.resource_info)
print(allocation_context.resource_id)
allocation_context.unlock()
# or using resource info
lockable.unlock(allocation_context)

Allocation context contains following API:

• requirements: dict Original requirements for allocation
• resource_info: dict Allocated resource information
• unlock(): func release resource lock function
• allocation_queue_time: timedelta How long waited before allocation
• allocation_start_time: datetime when allocation was started
• release_time: datetime when allocation was ended
• alloc_id: str allocation id
• allocation_durations: timedelta how long time allocation takes

or using context manager which unlock automatically

with lockable.auto_lock(requirements, [timeout_s]) as allocation:
    print(allocation.resource_info)

Resource requirements are evaluated using mongoquery, so MongoDB-style operators like $in and $gt are supported when selecting resources.

Tips:

You can allocate also offline devices by set requirements "online": None . You can ignore also hostname same same way by setting it to None`