The libflom programming kompass for C++ developers

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

• flom.hh is the header file you must include
• FlomHandle is the class you must use to communicate with FLoM (you must treat this type of objects as opaque objects: 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)
• you can use a “static programming style”, allocating FlomHandle objects on the stack or you can use a “dynamic programming style”, allocating FlomHandle objects in the heap: that’s your choice and FLoM API does not force you to use a specific style

Static programming style example

BasicStatic.cc example can be considered the hello world FLoM equivalent for static programming style:

1. allocate a FlomHandle object on the stack declaring it
2. synchronize your program using method lock()
3. do everything your program must perform inside the synchronization window
4. deserialize your program using method unlock()

Note: C++ clean-ups every statically initialized FlomHandle object for you: you don’t have to mind about memory leaks.

Dynamic programming style example

BasicDynamic.cc example can be considered the hello world FLoM equivalent for dynamic programming style:

1. declare a FlomHandle object pointer
2. create a new object using new
3. synchronize your program using method lock()
4. do everything your program must perform inside the synchronization window
5. desynchronize your program using method unlock()
6. delete the object using delete

Note: you must delete every created FlomHandle object; if you don’t delete every object you will generate memory leaks.

Advanced examples

Basic examples do 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.
AdvancedStatic.cc and AdvancedDynamic.cc examples show 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:

• FLoM classes C++ API page
• FlomHandle.hh header file

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.
Method unlockRollback 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.cc.