The libflom programming kompass for Python developers

FLoM API is very easy to understand and use; these are the basic concepts:

• flom is the package you must include
• flom_handle_t is the data type you must use to communicate with FLoM (you must treat this type of object as an opaque object: for every useful property there’s a getter/setter method and you don’t have to mind what’s the meaning of the object content)

Basic programming example

basic.py example can be considered the hello world FLoM equivalent for Python programming:

1. allocate a flom_handle_t object
2. initialize the object using method (function) flom_handle_init
3. synchronize your program using method (function) flom_handle_lock
4. do everything your program must perform inside the synchronization window
5. desynchronize your program using method (function) flom_handle_unlock
6. clean-up the object using method (function) flom_handle_clean

Note: you must clean-up every initialized flom_handle_t object; if you don’t clean-up every object you will generate memory leaks.

Advanced programming example

Basic example does not explain as you can specify the name of the logical resource, the quantity of a numerical resource and the other parameters you typically use with flom command line.
advanced.py example shows how some properties can be set before entering in the synchronization phase.
The complete list of the available setter/getter methods can be retrieved from:

• functions C API page

Note: Python libflom wrapper exposes the same functions provided by the C basic library.

Transactional example

Some resources, for example unique sequences, can be declared as transactional.
A transactional resource has an associated state and it needs an explicit unlock to commit the state.
If a transactional resource is not committed due to a program crash, the state will be rolled back.
Function flom_handle_unlock_rollback has been introduced to force a state rollback during the unlock phase, even if a program does not crash.
An example is available in this source code: transactional.py.